To protect a person from mechanical injury, two main methods are used: ensuring the inaccessibility of a person to dangerous areas and the use of devices that protect a person from a dangerous factor. Means of protection against mechanical injury are divided into collective (SKZ) and individual (PPE). SKZ are divided into protective, safety, braking devices, automatic control and signaling devices, remote control, safety signs.
Protective devices designed to prevent accidental entry of a person into the danger zone.
Safety devices are designed for automatic shutdown of machines and equipment in case of deviation from the normal mode of operation or when a person enters the danger zone. They are divided into blocking and restrictive.
2. Electric shock protection
The defeat of a person by electric current is possible only when the electrical circuit is closed through his body or, in other words, when a person touches the network at least at two points. This happens: with a two-phase connection to the network; when connected to a single-phase network or in contact with live parts of equipment (terminals, tires, etc.); upon contact with non-current-carrying parts of the equipment (machine body, cash register, etc.), which accidentally become energized due to a violation of the wire insulation (emergency mode); when step voltage occurs.
The current can be reduced either by reducing touch voltage, or by increasing the resistance of the human body, for example, when using PPE
Step voltage called the tension between two points on which a person stands at the same time. This occurs when a bare wire falls to the ground, when approaching the ground electrode in the mode of current flowing through it, etc.
Classification of premises according to the danger of electric shock. All premises are divided according to the degree of danger into three classes: without increased danger, increased danger, especially dangerous.
Premises without increased danger- these are dry, dust-free rooms with normal air temperature and with insulating (for example, wooden) floors, i.e., in which there are no conditions inherent in rooms with increased danger and especially dangerous.
Premises of increased danger characterized by the presence of one of the following five conditions that create an increased risk: dampness, when the relative humidity of the air exceeds 70% for a long time; such premises are called damp; high temperature, when the air temperature for a long time (over a day) exceeds + 30 ° C; such rooms are called hot; conductive dust, when, according to the conditions of production, conductive technological dust (for example, coal, metal, etc.) is released in the premises in such an amount that it settles on wires, penetrates into machines, devices, etc.; such rooms are called dusty with conductive dust; conductive floors - metal, earthen, reinforced concrete, brick, etc.; the possibility of a person simultaneously touching the metal structures of buildings connected to the ground, technological devices, mechanisms, etc., on the one hand, and to the metal cases of electrical equipment, on the other.
Premises especially dangerous are characterized by the presence of one of the following three conditions that create a special danger: special dampness, when the relative humidity of the air is close to 100% (walls, floors and objects in the room are covered with moisture); such rooms are called especially damp; chemically active or organic environment, i.e. rooms that constantly or for a long time contain aggressive vapors, gases, liquids that form deposits or mold, which act destructively on insulation and current-carrying parts of electrical equipment; such rooms are called rooms with a chemically active or organic environment; the simultaneous presence of two or more conditions characteristic of premises with increased danger.
Particularly dangerous premises is a large part of the production facilities, including all workshops of machine-building plants, testing stations, galvanizing workshops, workshops, etc. The same premises include areas of work on the ground in the open air or under a canopy.
Application of low voltages. Low voltage is a voltage of not more than 42 V, used to reduce the risk of electric shock to a person. The greatest degree of safety is achieved at voltages up to 10 V. In practice, the use of very low voltages is limited to miner's lamps (2.5 V) and some household appliances (flashlights, toys, etc.). In production, voltages of 12 and 36 V are used. In areas with increased danger for portable electrical devices, it is recommended to use a voltage of 36 V. In especially dangerous areas, hand-held power tools are powered by 36 V, and hand-held electric lamps - 12 V. These voltages do not provide complete safety, but only significantly reduce the risk of electric shock.
Voltages of 12, 36 and 42 V are used in rooms with increased danger and especially dangerous for the use of hand-held electrified tools, hand-held portable lamps and local lighting lamps.
Electrical separation of the network. An extensive electrical network of great length has a significant electrical capacitance. In this case, even touching one phase is very dangerous. If the network is divided into a number of small networks of the same voltage, which will have a small capacitance and high insulation resistance, then the danger of damage is sharply reduced. Typically, the electrical separation of networks is carried out by connecting individual electrical installations through isolating transformers.
Control and prevention of damaged insulation- the most important element of ensuring electrical safety. When commissioning new and overhauled electrical installations, acceptance tests are carried out with insulation resistance control.
Protection against touching the current-carrying parts of installations. Touching live parts is always dangerous even in networks up to 1000 V and with good phase isolation. To eliminate the danger of touching live parts, it is necessary to ensure their inaccessibility.
Protective ground. Protective grounding is the intentional electrical connection to the ground of metal non-current-carrying parts of electrical installations that may be energized.
Grounding device- this is a set of grounding conductors - metal conductors that are in direct contact with the ground, and grounding conductors connecting the body of the electrical installation with the grounding conductor. Grounding devices are of two types: remote or concentrated and contour or distributed.
Zeroing.
Zeroing is the intentional electrical connection with a zero protective conductor of metal non-current-carrying parts of installations that may be energized. Zeroing is used in four-wire networks with voltages up to 1000 V with a dead-earthed neutral.
Zero protective conductor called a conductor connecting the zeroed parts of the installation with the grounded neutral of the current source (generator, transformer) or with the zero working conductor, which in turn is connected to the neutral of the current source.
Residual current devices (RCD)- this is a high-speed protection that provides automatic shutdown of the electrical installation in the event of a danger of electric shock to a person.
To PPE from electric shock are insulating means, which are divided into basic and additional. The former withstand a long time of action of the voltage, the latter do not. In networks with voltages up to 1000 V, the main PPE include: insulating rods, insulating electrical clamps, dielectric gloves, plumbing and assembly tools with insulated handles, voltage indicators; over 1000 V - insulating rods, insulating and electrical clamps, voltage indicators. To additional PPE include: in networks with voltages up to 1000 V - dielectric galoshes, rugs, insulating stands; over 1000 V - dielectric gloves, boots, mats, insulating pads. PPE must be marked with the voltage for which they are designed, their insulating properties are subject to periodic checks in a timely manner.
3. ESD protection
For protection against static electricity, a method is used that excludes or reduces the formation of static electricity charges, and a method that eliminates charges.
Charge elimination method. The main technique for eliminating charges is the grounding of electrically conductive parts of technological equipment to drain the resulting charges of static electricity into the ground. For this purpose, you can use the usual protective earth, designed to protect against electric shock.
Effective way reduction of electrification of materials and equipment in production is the use of static electricity neutralizers, which create positive and negative ions near electrolyzed surfaces.
4. Protection from energy impacts
Protection from energy influences is carried out by three main methods: by limiting the time a person stays in the zone of action of the physical field, by moving him away from the source of the field, and by using protective equipment, of which screens are the most common. Shielding effectiveness is usually expressed in decibels (dB).
To protect against vibration, the following methods are used: reducing the vibration activity of machines; detuning from resonant frequencies; vibration damping; vibration isolation; vibration damping, as well as personal protective equipment.
Decreased vibration activity of machines achieved by changing the technological process, using machines with such kinematic schemes in which the dynamic processes caused by impacts, accelerations, etc. would be excluded or reduced to the maximum, for example, by replacing riveting with welding; good dynamic and static balancing of mechanisms, lubrication and cleanliness of processing of interacting surfaces; the use of kinematic gearings of reduced vibration activity, for example, chevron and helical gears instead of spur gears; replacement of rolling bearings with plain bearings; the use of structural materials with increased internal friction.
Detuning from resonant frequencies consists in changing the operating modes of the machine and, accordingly, the frequency of the disturbing vibration force; natural vibration frequency of the machine by changing the rigidity of the system c (for example, installing stiffeners) or changing the mass m of the system (for example, by attaching additional masses to the machine).
vibration damping- this is a method of reducing vibration by strengthening friction processes in the structure, dissipating vibrational energy as a result of its irreversible conversion into heat during deformations that occur in the materials from which the structure is made.
Vibration damping(increase in the mass of the system m) is carried out by installing the units on a massive foundation.
Rigidity increase system (increase c), for example by installing stiffeners. This method is effective only at low vibration frequencies.
Vibration isolation is to reduce the transmission of vibrations from the source to the protected object. project with the help of devices placed between them. For vibration isolation, vibration-isolating supports such as elastic gaskets, springs, or combinations thereof are most often used.
To protect against noise, the following methods are used: reducing the sound power of the noise source; placement of the noise source relative to workplaces and populated areas, taking into account the directionality of the radiation of sound energy; acoustic treatment of premises; soundproofing; the use of noise suppressors; use of personal protective equipment.
Noise protection PPE includes earmuffs, earmuffs and helmets.
3. Protection against electromagnetic fields and radiation
To protect against electromagnetic fields and radiation, the following methods and means are used: reducing the radiation power directly in its source, in particular through the use of electromagnetic energy absorbers; increasing the distance from the radiation source; rise of emitters and radiation patterns; blocking radiation or reducing its power for scanning emitters (rotating antennas) in the sector in which the protected object is located (populated area, workplace); radiation shielding; use of personal protective equipment.
They shield either radiation sources or areas where a person can be. Screens can be closed (completely isolating the radiating device or protected object) or open, of various shapes and sizes, made of solid, perforated, honeycomb or mesh materials.
Screens partially reflect and partially absorb electromagnetic energy. According to the degree of reflection and absorption, they are conditionally divided into reflective and absorbing. Reflective screens are made of highly conductive materials, such as steel, copper, aluminum with a thickness of at least 0.5 mm. The thickness is assigned from structural and strength considerations.
Absorbing screens are made of radio absorbing materials. There are no natural materials with good radio absorbing ability, so they are made using various design techniques and the introduction of various absorbing additives into the base.
To PPE, which will be used to protect against electromagnetic radiation, include radio protective suits, overalls, aprons, glasses, masks, etc.
4. Protection against ionizing radiation
To protect against ionizing radiation, it is necessary to increase the distance from the source of radiation, shield the radiation with the help of screens and biological shields; apply PPE.
To reduce the radiation level to acceptable values, screens are installed between the radiation source and the protected object (person). To select the type and material of the screen, its thickness, data on the attenuation ratio of radiation of various radionuclides and energies are used, presented in the form of tables or graphical dependencies.
The choice of protective screen material is determined by the type and energy of radiation.
5. Protection during the operation of the PC
Prolonged work on a PC can adversely affect human health. A PC and, above all, a PC (personal computer) monitor is a source of an electrostatic field; weak electromagnetic radiation in the low-frequency and high-frequency ranges (2 Hz ... 400 kHz); x-ray radiation; ultraviolet radiation; infrared radiation; visible radiation.
Safe levels of radiation are regulated by the standards of the State Committee for Sanitary and Epidemiological Supervision “Hygienic requirements for video display terminals and PCs and organization of work. Sanitary norms and rules. 1996".
Most monitors these days are labeled Low Radiation.
A technology has been developed to protect against electrostatic, variable electrical and magnetic components of EMR by applying electrically conductive coatings to the inner surface of the monitor housing and grounding it, and integrating an optical protective filter into the display that protects from radiation from the screen.
For monitors of obsolete designs that do not meet modern safety requirements in terms of radiation levels and have not yet been decommissioned, it is recommended to use protective filters (PF) designed for installation on the screen.
When working on a PC, organization of work is very important. The room in which the PCs are located should be spacious and well ventilated. The minimum area for one computer is 6 m 2 , the minimum volume is 20 m 2 .
Proper organization of lighting in the room is very important.
5. Protection of the atmosphere from harmful emissions
The purpose of protecting the atmosphere from harmful emissions and emissions is to ensure that the concentration of harmful substances in the air of the working area and the surface layer of the atmosphere is equal to or less than the MAC.
The goal is achieved by using the following methods and means: rational placement of sources of harmful emissions in relation to populated areas and workplaces; dispersion of harmful substances in the atmosphere to reduce concentrations in its surface layer, removal of harmful emissions from the source of formation through local or general exhaust ventilation; the use of means of air purification from harmful substances; using PPE.
Cleaning systems. The main parameters of air (gas) purification systems are efficiency and hydraulic resistance. Efficiency determines the concentration of harmful impurities at the outlet of the apparatus, and hydraulic resistance determines the energy costs for passing the gases to be purified through the apparatus. The higher the efficiency and the lower the hydraulic resistance, the better.
The range of existing gas-cleaning devices is significant, and their technical capabilities make it possible to provide high degrees of purification of exhaust gases for almost all substances. To clean exhaust gases from dust, there is a wide range of devices that can be divided into two large groups: dry and wet (scrubbers) irrigated with water.
Dry type dust collectors. Cyclones of various types are widely used: single, group, battery.
There are many different types of cyclones, but the most widely used are TsN and SK-TsN (SK-soot conical) cyclones, which can be used to solve most dust collection tasks.
Widely used in dust collection filters, which provide high efficiency of catching large and small particles. The purification process consists in passing the gas to be purified through a porous partition or a layer of porous material. The baffle works like a sieve, preventing particles larger than the pore diameter from passing through. Particles of a smaller size penetrate into the partition and are retained there due to inertial, electrical and diffusion trapping mechanisms, some simply wedged in curved and branched pore channels. According to the type of filter material, filters are divided into fabric, fibrous and granular.
Wet type dust collectors. It is advisable to use them for cleaning high-temperature gases, catching fire and explosion hazardous dusts, and in cases where, along with dust trapping, it is required to trap toxic gas impurities and vapors. Wet type devices are called scrubbers. The range of types of devices is diverse.
To remove harmful gas impurities from exhaust gases, the following methods are used: absorption, chemisorption, adsorption, thermal afterburning, catalytic neutralization.
Absorption- this is the phenomenon of dissolution of a harmful gaseous impurity by a sorbent, usually water.
Chemisorption used to capture gas impurities, insoluble or poorly soluble in water. The method of chemisorption consists in the fact that the gas to be purified is irrigated with solutions of reagents that enter into a chemical reaction with harmful impurities to form non-toxic, low-volatile or insoluble chemical compounds. This method is widely used to capture sulfur dioxide.
Adsorption consists in trapping by the surface of a microporous adsorbent (activated carbon, silica gel, zeolites) molecules of harmful substances. The method has a very high efficiency, but strict requirements for gas dustiness - no more than 2...5 mg/m 3 .
Thermal afterburning- this is the process of oxidation of harmful substances by atmospheric oxygen at high temperatures (900 ... 1200 ° C). With the help of thermal afterburning, toxic carbon monoxide is oxidized to non-toxic carbon dioxide CO.
catalytic neutralization is achieved by using catalysts - materials that accelerate reactions or make them possible at much lower temperatures (250 - 400 0 C).
In polluted air, respirators and gas masks will be used as personal protective equipment.
6. Protection of the hydrosphere from harmful discharges
The task of cleaning harmful discharges is no less, and even more complex and large-scale than cleaning industrial emissions. In contrast to the dispersion of emissions in the atmosphere, the dilution and reduction of concentrations of harmful substances in water bodies is worse, the aquatic environment is more vulnerable and sensitive to pollution.
Protection of the hydrosphere from harmful discharges is carried out using the following methods and means: rational placement of sources of discharges and organization of water intake and drainage; dilution of harmful substances in water bodies to acceptable concentrations using specially organized and dispersed releases; using wastewater treatment products.
In order to stimulate enterprises to high-quality purification of their own wastewater, it is advisable to organize water intake for technological needs downstream of the river than wastewater discharge. If, at the same time, clean water is required for technological needs, the enterprise will be forced to carry out highly efficient treatment of its own wastewater.
Dispersed outlets of effluents are carried out through pipes laid across the river bed, this increases the intensity of mixing and the multiplicity of dilution of effluents.
Wastewater treatment methods can be divided into mechanical, physico-chemical and biological.
Mechanical wastewater treatment from suspended particles (solid particles, particles of fat, oil and oil products) is carried out by filtering, settling, processing in the field of centrifugal forces, filtering, flotation.
Straining used to remove large and fibrous inclusions from wastewater.
settling based on the free settling (floating) of impurities with a density greater (lower) than the density of water.
Settling tanks used for gravitational separation of finer suspended particles or fatty substances from wastewater.
Wastewater treatment in the field of centrifugal force carried out in hydrocyclones.
Filtration used for wastewater treatment from fine impurities both at the initial and final stages of treatment.
Flotation It consists in enveloping the particles of impurities with small bubbles of air supplied to the wastewater and raising them to the surface, where a layer of foam is formed.
Physical and chemical cleaning methods used to remove soluble impurities from wastewater (heavy metal salts, cyanides, fluorides, etc.), and in some cases to remove suspended matter. As a rule, physicochemical methods are preceded by the stage of purification from suspended solids. Of the physicochemical methods, the most common are electroflotation, coagulation, reagent, ion-exchange, etc.
7. Utilization and disposal of solid and liquid waste. Low-waste and resource-saving technologies
According to the state of aggregation, waste is divided into solid and liquid. According to the source of formation, industrial, generated during the production process (metal scrap, shavings, plastics, dust, ash, etc.), biological, generated in agriculture (bird droppings, animal waste, crop waste and other organic waste), household (in particular, precipitation from municipal wastewater), radioactive. In addition, waste is divided into combustible and non-combustible, compressible and non-compressible.
Wastes that can later be used in production are secondary material resources.
The most important stage of waste management is their collection.
After collection, the waste is recycled, recycled and disposed of. Waste that can be useful is recycled.
The most important stage in the process of subsequent processing and use of household waste is their separation already at the stage of their collection in places of generation, i.e. directly in residential areas.
Waste that cannot be processed and further used as secondary resources (the processing of which is difficult and economically unprofitable, or which is in excess) is disposed of in landfills. Waste with a high degree of moisture is dehydrated before disposal at the landfill. Compressible waste should be compressed, and combustible - burned in order to reduce their volume and weight. When pressing, the volume of waste is reduced by 2 ... 10 times, and when burned - up to 50 times.
Incineration in incinerators has become widespread.
Waste is stored in landfills.
Landfills are of different levels and classes: landfills of enterprises, urban, regional significance. The landfills are equipped to protect the environment, and waterproofing is carried out at the storage sites to prevent groundwater pollution.
Processing and disposal of radioactive waste is one of the most difficult problems. Collection, processing and disposal of radioactive waste is carried out separately from other types of waste. It is also expedient to subject solid radioactive waste to compaction and incineration in special facilities equipped with radiation protection and a highly efficient system for cleaning ventilation air and exhaust gases. When burning 85…90%
Burial of radioactive waste is carried out in burial grounds in geological formations.
Low-waste and resource-saving technologies. A radical solution to the problems of protection against industrial waste is possible with the widespread introduction of low-waste technologies. The concept of "wasteless technology" is often used. This is a misnomer, as waste-free technologies do not exist. A low-waste technology is a technology in which all components of raw materials and energy are rationally used in a closed cycle, i.e., the use of primary natural resources and the resulting waste are minimized.
All employees must comply with safety regulations when operating machinery, pressure vessels, lifting equipment, etc. mechanical injury protection safety
Failure to comply with and a clear violation of precautionary measures when servicing machinery and equipment can lead to a large number of accidents, sometimes fatal.
Injuries, as a rule, are not the result of an accidental combination of circumstances, but of existing dangers that were not eliminated in a timely manner. Therefore, each head of a section, workshop, etc. is obliged to know and explain to his subordinates on a daily basis the safety rules, to show a personal example of their impeccable observance. It is designed to relentlessly and constantly require workers to strictly comply with safety regulations, so there are means of protection against mechanical injury.
To protect against mechanical injury, two main methods are used:
- - ensuring the inaccessibility of a person to dangerous areas;
- - the use of devices that protect a person from a dangerous factor.
Means of protection against mechanical injury are divided into:
- - individual (PPE).
- - collective (SKZ)
Consider what personal means of protection against mechanical injury exist.
In a number of enterprises, there are such types of work or working conditions in which an employee may be injured or otherwise exposed to health hazards. Even more dangerous conditions for people can arise during accidents and liquidation of their consequences. In these cases, PPE must be used to protect the person. Their use should ensure maximum safety, and the inconvenience associated with their use should be minimized. This is achieved by following the instructions for their use. The latter regulate when, why and how PPE should be used, what should be the care for them.
The range of PPE includes an extensive list of items used in production environments (PPE for everyday use), as well as items used in emergency situations (PPE for short-term use). In the latter cases, mainly insulating personal protective equipment (IPPE) is used.
When performing a number of production operations (in the foundry, in electroplating shops, during loading and unloading, machining, etc.), it is necessary to wear overalls (suits, overalls, etc.) made of special materials to ensure safety from the effects of various substances and materials with which you have to work, thermal and other radiation. The requirements for workwear are to provide the greatest comfort for the person, as well as the desired safety. For some types of work, aprons can be used to protect overalls, for example, when working with coolants and lubricants, during thermal exposure, etc. In other conditions, it is possible to use special oversleeves,
Protective footwear (boots, boots) must be worn to avoid injuries to the feet and toes. It is used in the following works: with heavy objects; in construction; in conditions where there is a risk of falling objects; in rooms where the floors are flooded with water, oil, etc.
Some types of safety shoes are equipped with reinforced soles that protect the foot from sharp objects (such as a protruding nail). Shoes with special soles are designed for those working conditions in which there is a risk of injury when falling on slippery ice filled with water and oil. Special anti-vibration shoes are used.
To protect hands when working in electroplating shops, foundries, during the mechanical processing of metals, wood, during loading and unloading, etc. it is necessary to use special mittens or gloves. Protection of hands from vibrations is achieved by using mittens made of resiliently damping material.
Head protection is designed to protect the head from falling and sharp objects, as well as to soften impacts. The choice of helmets and helmets depends on the type of work performed. They must be used under the following conditions:
- - there is a risk of injury from materials, tools or other sharp objects that fall down, tip over, slide off, are thrown or thrown down;
- - there is a danger of collision with sharp protruding or twisting objects, pointed objects, objects of irregular shape, as well as with hanging or swinging weights;
- - there is a risk of head contact with the electrical wire.
It is very important to choose a helmet according to the nature of the work to be done, as well as in size, so that it fits firmly on the head and provides sufficient distance between the inner shell of the helmet and the head. If the helmet is cracked or has been subjected to severe physical or thermal stress, it should be discarded.
To protect against harmful mechanical, chemical and radiation effects, protective equipment for the eyes and face is necessary. These tools are used when performing the following work: grinding, sandblasting, spraying, spraying, welding, as well as when using caustic liquids, harmful thermal effects, etc. These tools are made in the form of glasses or shields. In some situations, eye protection is used together with respiratory protection, for example, special headgear.
In working conditions where there is a risk of radiation exposure, for example, during welding, it is important to select protective filters of the required degree of density. When using eye protection, it is necessary to ensure that they are securely held on the head and do not reduce the field of view, and pollution does not impair vision.
Hearing protectors are used in noisy industries, when servicing power plants, etc. There are different types of hearing protection: ear plugs and earmuffs. The correct and constant use of hearing protection reduces the noise load for earplugs by 10-20, for headphones by 20-30 dBA.
Respiratory protection means are designed to protect against inhalation and ingress of harmful substances (dust, steam, gas) into the human body during various technological processes. When choosing personal respiratory protection equipment (PPE), you need to know the following: what substances you have to work with; what is the concentration of pollutants; how much time you have to work; in what state are these substances: in the form of gas, vapor or aerosols; is there a danger of oxygen starvation; what are the physical loads in the process of work.
There are two types of respiratory protective equipment: filtering and insulating. Filtering filters supply air from the working area purified from impurities into the breathing zone, insulating - air from special containers or from a clean space located outside the working area.
Insulating protective equipment should be used in the following cases: in conditions of a lack of oxygen in the inhaled air; in conditions of air pollution in high concentrations or in the case when the concentration of pollution is unknown; in conditions where there is no filter that can protect against contamination; in the event that heavy work is performed, when breathing through the filter RPE is difficult due to the resistance of the filter.
If there is no need for insulating protective equipment, filter media must be used. The advantages of filter media are lightness, freedom of movement for the worker; ease of decision when changing jobs.
The disadvantages of filter media are as follows: filters have a limited shelf life; difficulty breathing due to filter resistance; limited work with the use of a filter in time, if we are not talking about a filtering mask, which is equipped with blowing. You should not work with the use of filtering PPE for more than 3 hours during the working day.
For work in especially dangerous conditions (in isolated volumes, during the repair of heating furnaces, gas networks, etc.) and emergency situations (in case of fire, emergency release of chemical or radioactive substances, etc.), ISIZ and various indium-ideal devices are used . They find the use of ISIZ from thermal, chemical, ionizing and bacteriological effects. The range of such ISIS is constantly expanding. As a rule, they provide comprehensive protection of a person from dangerous and harmful factors, simultaneously creating protection for the organs of vision, hearing, breathing, as well as protection for individual parts of the human body.
Personnel cleaning the premises, as well as those working with radioactive solutions and powders, should be provided (in addition to the overalls and special footwear listed above) with plastic aprons and oversleeves or plastic half-robes, additional special footwear (rubber or plastic) or rubber boots. When working in conditions of possible contamination of indoor air with radioactive aerosols, it is necessary to use special filtering or insulating respiratory protection equipment. Insulating PPE (pneumosuits, pneumohelmets) are used during work when filtering agents do not provide the necessary protection against the ingress of radioactive and toxic substances into the respiratory system.
When working with radioactive substances, daily use items include gowns, overalls, suits, special footwear and some types of dust respirators. Overalls for everyday use are made of cotton fabric (outerwear and underwear). If the impact on the worker of aggressive chemicals is possible, the outerwear is made from synthetic materials - lavsan.
The means of short-term use include insulating hose and self-contained suits, pneumosuits, gloves and film clothing: aprons, oversleeves, semi-overalls. Plastic clothing, insulating suits, safety shoes are made of durable, easily decontaminated polyvinyl chloride plastic with frost resistance up to -25 ° C or plastic compound reinforced with nylon mesh of 80 AM formulation.
SCs are divided into:
- - protective;
- - safety;
- - braking devices;
- - automatic control and alarm devices;
- - remote control devices;
- - safety signs.
Protective devices
Protective devices - a class of protective equipment that prevents a person from entering the danger zone. Protective devices are used to isolate drive systems for machines and assemblies, workpiece processing areas on machine tools, presses, dies, exposed live parts, areas of intense radiation (thermal, electromagnetic, ionizing), areas for the release of harmful substances that pollute the air, etc. Enclose also working areas located at a height (forests, etc.).
Constructive solutions for protective devices are very diverse. They depend on the type of equipment, the location of a person in the working area, the specifics of hazardous and harmful factors that accompany the technological process. In accordance with GOST 12.4.125-83, means of protection against mechanical injury, protective devices are divided into:
- - by design - casings, doors, shields, peaks, slats, barriers and screens;
- - according to the manufacturing method - solid, non-solid (perforated, mesh, lattice) and combined;
- - according to the method of installation - stationary and mobile.
Examples of a complete stationary fence are the fences of electrical equipment switchgear, the casing of tumbling drums, the casing of electric motors, pumps, etc.; partial fencing of cutters or the working area of the machine. It is possible to use a movable (removable) fence. It is a device interlocked with the working bodies of a mechanism or machine, as a result of which it closes access to the working area when a dangerous moment occurs. Such restrictive devices are especially widespread in the machine tool industry (for example, in OFZ-36 CNC machines).
Portable fences are temporary. They are used in repair and adjustment work to protect against accidental contact with live parts, as well as from mechanical injury and burns. In addition, they are used at permanent workplaces of welders to protect others from the effects of an electric arc and ultraviolet radiation (welding posts). They are most often performed in the form of shields 1.7 m high.
The design and material of the enclosing devices are determined by the features of the equipment and the technological process as a whole. Fences are made in the form of welded and cast casings, gratings, meshes on a rigid frame, as well as in the form of rigid solid shields (shields, screens). The dimensions of the cells in the mesh and lattice fencing will be determined in accordance with GOST 12.2.062-81. Metals, plastics, and wood are used as fencing materials. If it is necessary to monitor the working area, in addition to grids and gratings, solid protective devices made of transparent materials (plexiglass, triplex, etc.) are used.
Guards must be strong enough to withstand the loads from flying particles during processing and accidental impacts of operating personnel. When calculating the strength of the fences of machines and units for processing metals and wood, it is necessary to take into account the possibility of flying out and hitting the fence of the workpieces being processed.
The design of production equipment powered by electrical energy must include devices (means) to ensure electrical safety.
For the purpose of electrical safety, technical methods and means are used (often in combination with one another): protective grounding, grounding, protective shutdown, potential equalization, low voltage, electrical separation of the network, isolation of live parts, etc.
Electrical safety must be ensured:
- - design of electrical installations;
- - technical methods and means of protection;
- - organizational and technical measures.
Electrical installations and their parts must be designed in such a way that workers are not exposed to dangerous and harmful effects of electric current and electromagnetic fields, and comply with electrical safety requirements.
To ensure protection against accidental contact with live parts, the following methods and means must be used:
- - protective shells;
- - protective fences (temporary or stationary);
- - safe location of current-carrying parts;
- - insulation of current-carrying parts (working, additional, reinforced, double);
- - isolation of the workplace;
- - low voltage;
- - protective shutdown;
- - warning signaling, blocking, safety signs.
To provide protection against electric shock when when touching metal non-current-carrying parts that may become energized as a result of damage to the insulation, the following methods are used:
- - protective grounding;
- - zeroing;
- - equalization of potential;
- - system of protective wires;
- - protective shutdown;
- - insulation of non-current-carrying parts;
- - electrical separation of the network;
- - low voltage;
- - insulation control;
- - compensation of earth fault currents;
- -individual protection means.
Technical methods and means are used separately or in combination with each other so that optimal protection is provided.
Electrostatic intrinsic safety should be ensured by creating conditions that prevent the occurrence of static electricity discharges that can become a source of ignition of protected objects.
For protection of workers from static electricity it is possible to apply antistatic substances to the surface, add antistatic additives to flammable dielectric liquids, neutralize charges using neutralizers, humidify the air up to 65-75%, if it is permissible according to the process conditions, remove charges by grounding equipment and communications.
Safety devices
Safety devices are designed to automatically turn off machines and equipment in case of deviation from the normal mode of operation or when a person enters the danger zone. Thus, in case of emergency conditions (increase in pressure, temperature, operating speeds, current strength, torques, etc.), the possibility of explosions, breakdowns, and ignitions is excluded.
They are divided into:
- - blocking;
- - restrictive.
Blocking devices exclude the possibility of a person entering the danger zone.
According to the principle of action, they can be:
- - mechanical;
- - electromechanical;
- - electromagnetic (radio frequency);
- - photoelectric;
- - optical
- - radiation;
- - pneumatic;
- - ultrasonic, etc.
Mechanical interlock is a system that provides communication between the fence and the braking (starting) device. When the guard is removed, the unit cannot be braked, and, therefore, it cannot be started.
Electrical interlocking is used in electrical installations with a voltage of 500 V and above, as well as in various types of technological equipment with an electric drive. It ensures that the equipment is switched on only when there is a fence. Electromagnetic (radio frequency) blocking is used to prevent a person from entering the danger zone. If this happens, the high frequency generator supplies a current pulse to the electromagnetic amplifier and the polarized relay. The contacts of the electromagnetic relay de-energize the magnetic starter circuit, which provides electromagnetic braking of the drive in tenths of a second. Magnetic blocking works similarly, using a constant magnetic field.
Photoelectric blocking is widely used, based on the principle of converting the light flux incident on the photocell into an electrical signal. The danger zone is protected by light rays. Crossing a light beam by a person causes a change in the photocurrent and activates the mechanisms for protecting or shutting down the installation. Used on subway turnstiles.
Optical blocking finds application in forging and pressing and machine shops of machine-building plants. The light beam falling on the photocell ensures a constant current flow in the winding of the blocking electromagnet. If at the moment the pedal is pressed, the worker’s hand is in the working (dangerous) zone of the stamp, the fall of the light current on the photocell stops, the windings of the blocking magnet are de-energized, its anchor is extended under the action of the spring, and turning on the press with the pedal becomes impossible.
Radiation blocking is based on the use of radioactive isotopes. Ionizing radiation directed from the source is captured by a measuring and command device that controls the operation of the relay. When crossing the beam, the measuring and commanding device sends a signal to the relay, which breaks the electrical contact and turns off the equipment.
The pneumatic blocking circuit is widely used in units where the working fluids are under high pressure: turbines, compressors, blowers, etc. Its main advantage is low inertia.
Restrictive devices- these are elements of mechanisms and machines, designed for destruction (or failure) during overloads.
These elements include:
- - shear pins and keys connecting the shaft with the drive;
- - friction clutches that do not transmit movement at high torques, etc.
They are divided into two groups:
- - elements with automatic restoration of the kinematic chain after the controlled parameter has returned to normal (for example, friction clutches);
- - elements with the restoration of the kinematic connection by replacing it (for example, pins and keys).
Brake devices.
By design, they are divided into:
- - block;
- - disk;
- - conical;
- - wedge.
Most often used shoe and disc brakes.
An example of such brakes can be the brakes of automobiles.
According to the principle of action are divided into:
- - manual;
- - semi-automatic
- - automatic
Automatic control and alarm devices
Control devices? these are instruments for measuring pressure, temperature, static and dynamic loads and other parameters that characterize the operation of equipment and machines.
The efficiency of their use is greatly increased when combined with alarm systems.
Automatic control and alarm devices are divided into:
by appointment:
- - informational;
- - warning;
- - emergency;
according to the way it works:
- - automatic;
- - semi-automatic.
Alarm systems are:
- - sound;
- - color;
- - light;
- - iconic;
- - combined
The following colors are used for signaling:
- - red? prohibitive, signals the need for immediate intervention, indicates a device whose operation is dangerous;
- - yellow? warning, indicates the approach of one of the parameters to the limiting, dangerous values;
- - green? informing about the normal mode of operation;
- - blue? signaling. Used for technical information about equipment operation.
The type of information signaling is various kinds of schemes, pointers, inscriptions.
Remote control devices(stationary and mobile) most reliably solve the problem of ensuring safety, as they allow you to control the operation of equipment from areas outside the danger zone.
Safety signs
Safety signs can be basic, additional, combined and group.
The main safety signs contain an unambiguous semantic expression of the safety requirements. The main signs are used independently or as part of combined and group safety signs.
Additional safety signs contain an explanatory inscription, they are used in combination with the main signs.
Combined and group safety signs consist of basic and additional signs and are carriers of complex safety requirements.
Types and execution of safety signs
Safety signs according to the types of materials used can be non-luminous, retroreflective and photoluminescent.
Non-luminous safety signs are made of non-luminous materials, they are visually perceived due to the scattering of natural or artificial light falling on them.
Retroreflective safety signs are made of retroreflective materials (or with the simultaneous use of retroreflective and non-luminous materials), they are visually perceived as luminous when their surface is illuminated by a beam (beam) of light directed from the side of the observer, and non-luminous - when their surface is illuminated with non-directional light from the side of the observer ( e.g. in general lighting).
Photoluminescent safety signs are made of photoluminescent materials (or with the simultaneous use of photoluminescent and non-luminous materials), they are visually perceived as glowing in the dark after the natural or artificial light ceases to act and non-luminous - with diffused lighting.
To increase the efficiency of visual perception of safety signs in particularly difficult conditions of use (for example, in mines, tunnels, airports, etc.), they can be made using a combination of photoluminescent and retroreflective materials.
Safety signs according to their design can be flat or three-dimensional.
Flat signs have one color-graphic image on a flat carrier and are well observed from one direction, perpendicular to the plane of the sign.
Three-dimensional signs have two or more color-graphic images on the sides of the corresponding polyhedron (for example, on the sides of a tetrahedron, pyramid, cube, octahedron, prism, parallelepiped, etc.). The colorographic image of three-dimensional characters can be observed from two or more different directions.
Flat safety signs can be with external illumination (illumination) of the surface by electric lamps.
Three-dimensional safety signs can be with external or internal electric lighting of the surface (backlight).
Safety signs with external or internal lighting must be connected to an emergency or autonomous power supply.
Flat and three-dimensional outdoor safety signs must be illuminated from the outdoor power supply network.
Fire safety signs placed on the evacuation route, as well as evacuation safety signs, must be made with external or internal lighting (illumination) from an emergency power supply or using photoluminescent materials.
Signs for designating emergency exits from auditoriums, corridors and other places without lighting should be three-dimensional with internal electric lighting from autonomous power supply and from the AC mains.
It is allowed to use metals, plastics, silicate or organic glass, self-adhesive polymer films, self-adhesive paper, cardboard and other materials as a carrier material, on the surface of which a color-graphic image of a safety sign is applied.
Safety signs must be made taking into account the specific conditions of placement and in accordance with safety requirements.
Signs with external or internal electric lighting for fire and explosion hazardous premises must be fireproof and explosion-proof, respectively, and for fire and explosion hazardous premises - explosion-proof.
Safety signs intended for placement in production environments containing aggressive chemical environments must withstand exposure to gaseous, vaporous and aerosol chemical environments.
Rules for the use of safety signs
Safety signs should be placed (installed) in the field of view of the people for whom they are intended. Safety signs must be located in such a way that they are clearly visible, do not distract attention and do not create inconvenience when people perform their professional or other activities, do not block passage, passage, do not interfere with the movement of goods. Safety signs placed on the gates and on the entrance doors of the premises mean that the zone of action of these signs extends to the entire territory and the area behind the gates and doors. Placement of safety signs on gates and doors should be carried out in such a way that the visual perception of the sign does not depend on the position of the gate or doors (open, closed).
If it is necessary to limit the scope of the safety sign, the corresponding instruction should be given in the explanatory inscription on the additional sign.
Safety signs based on non-luminous materials should be used in conditions of good and sufficient lighting.
Safety signs with external or internal lighting should be used in conditions of absence or insufficient lighting.
Retroreflective safety signs should be placed (installed) in places where there is no lighting or there is a low level of background lighting (less than 20 lux according to SNiP 23-05): when working using individual light sources, lamps (for example, in tunnels, mines, etc.) .p.), as well as to ensure safety when working on roads, highways, airports, etc.
Photoluminescent safety signs should be used where an emergency shutdown of light sources is possible, as well as elements of photoluminescent evacuation systems to ensure the independent exit of people from dangerous areas in case of accidents, fire or other emergencies.
To excite the photoluminescent glow of safety signs, it is necessary to have artificial or natural lighting in the room where they are installed.
The illumination of the surface of photoluminescent safety signs by light sources must be at least 25 lux. The orientation of safety signs in the vertical plane during installation (installation) in places of placement is recommended to be carried out according to the marking of the upper position of the sign.
It is allowed to fasten safety signs in their places of placement using screws, rivets, glue or other methods and fasteners that ensure their reliable retention during mechanical cleaning of premises and equipment, as well as their protection from possible theft.
To avoid possible damage to the surface of retroreflective signs in the places of mounting fasteners (peeling, twisting of the film, etc.), the heads of rotating fasteners (screws, bolts, nuts, etc.) should be separated from the front retroreflective surface of the sign with nylon washers.
The main safety signs can be:
- - forbidding;
- - warning;
- - prescriptive;
- - index;
- - firemen;
- - evacuation;
- - medical.
The main safety requirements for technical means and technological processes are regulated by the GOST, OST, SSBT, SanPiN, SN system, which establishes normative indicators for maximum permissible concentrations of substances and maximum permissible levels of intensity of energy flows.
To protect a person from mechanical injury, various means are used, which can be both collective and individual.
My work gave some recommendations on the use of collective and individual protective equipment against mechanical injury to workers, and also revealed working conditions in various areas of production, including occupational hazards and hazards, studied all collective and individual protective equipment (including overalls and safety shoes).
Bibliography
- 1. Anofrikov V.E., Bobok S.A., Dudko M.N., Elistratov G.D. Life Safety: Textbook. - M.: Mnemosyne, 1999.
- 2. Belova S.V. Life safety: Textbook for universities. - 2nd ed., corrected. and additional - M.: Higher. school, 1999;
- 3. Berezhnoy S.A., Romanov V.V., Sedov Yu.I. Life Safety: Textbook. - Tver: TSTU, 1996. - No. 722.
- 4. Denisov V.V. Life safety: Proc. allowance - M .: ICC March, Rostov n / D: ITs "March", 2003;
- 5. Ant L.A. Life safety: Proc. allowance for universities. - 2nd ed., revised. and additional - M.: UNITI, 2002;
- 6. Rusak O.N. Life safety. - St. Petersburg: MANEB, 2001.
- 7. Sagittarius V.M. Life safety: Proc. allowance for students. universities. - Rostov n / a: Phoenix, 2004;
- 8. Shlender P.E. Life safety: Proc. allowance, VZFEI - M.: Vuz. Study, 2003.
- 9. Shishikin N.K. Emergency Safety: A Textbook. - M.: Kanon, 2000.
Protection against mechanical injury
To protect against mechanical injury, two main methods are used:
* Ensuring the inaccessibility of a person to dangerous areas;
* the use of devices that protect a person from a dangerous factor.
Means of protection against mechanical injury are divided into:
* collective (SKZ;
* individual (PPE).
SCs are divided into:
* protective;
* safety;
* brake devices;
* automatic control and signaling devices;
* remote control;
* safety signs.
Protective devices.
Designed to prevent accidental entry of a person into the danger zone. They are used to isolate moving parts of machines, processing areas of machine tools, presses, impact elements of machines, etc. from the working area.
They can be:
* stationary;
* mobile;
* portable
They are made in the form of protective covers, doors, visors, barriers, screens.
Protective devices are made of metal, plastic, wood and can be either solid or mesh.
The working part of cutting tools (saws, milling cutters, cutter heads, etc.) must be closed by an automatically operating fence that opens during the passage of the material being processed or the tool only to pass it.
Guards must be strong enough to withstand loads from flying particles of the processed material, collapsing processing tools, from the breakdown of the workpiece, etc.
Portable fences are used as temporary during repair and adjustment work.
Safety devices are designed to automatically turn off machines and equipment in case of deviation from the normal mode of operation or when a person enters the danger zone.
They are divided into:
* blocking;
* restrictive.
Blocking devices exclude the possibility of a person entering the danger zone.
According to the principle of action, they can be:
* mechanical;
* electromechanical;
* electromagnetic (radio frequency);
* photoelectric;
* radiation;
* pneumatic;
* ultrasonic, etc.
Photoelectric blocking is widely used, based on the principle of converting the light flux incident on the photocell into an electrical signal. The danger zone is protected by light rays. Crossing a light beam by a person causes a change in the photocurrent and activates the mechanisms for protecting or shutting down the installation. Used on subway turnstiles.
Radiation blocking is based on the use of radioactive isotopes. Ionizing radiation directed from the source is captured by a measuring and command device that controls the operation of the relay. When crossing the beam, the measuring and commanding device sends a signal to the relay, which breaks the electrical contact and turns off the equipment.
Restrictive devices.
These are elements of mechanisms and machines designed for destruction (or failure) during overloads.
These elements include:
* shear pins and keys connecting the shaft with the drive;
* friction clutches that do not transmit movement at high torques, etc.
They are divided into two groups:
* elements with automatic restoration of the kinematic chain after the controlled parameter has returned to normal (for example, friction clutches);
* elements with the restoration of the kinematic connection by replacing it (for example, pins and keys).
Brake devices.
By design, they are divided into:
* block;
* disk;
* conical;
* wedge.
Most often used shoe and disc brakes.
An example of such brakes can be the brakes of automobiles.
Automatic control and alarm devices
Control devices are devices for measuring pressures, temperatures, static and dynamic loads and other parameters that characterize the operation of equipment and machines.
The efficiency of their use is greatly increased when combined with alarm systems.
Automatic control and alarm devices are divided into:
by appointment:
* information;
* warning;
* emergency;
P about the operation method:
* automatic;
* semi-automatic.
The following colors are used for signaling:
* red - forbidding;
* yellow - warning;
* green - notifying;
* blue - signaling.
The type of information signaling is various kinds of schemes, pointers, inscriptions.
Remote control devices (stationary and mobile) most reliably solve the problem of ensuring safety, as they allow you to control the operation of equipment from areas outside the danger zone.
Safety signs.
Their appearance is regulated by GOST R 12.4026-01.
They can be:
* forbidding;
* warning;
* prescriptive;
* index;
* firemen;
* evacuation;
* medical.
First aid for bleeding. There are arterial, venous and capillary bleeding. Blood from a gaping wound is poured out in a light red color rhythmically, in a pulsating stream with arterial bleeding, and a dark color in a continuous continuous stream with venous bleeding. Capillary bleeding - blood from damaged small vessels flows like a sponge.
When providing first aid, a temporary stop of bleeding is used.
A twist (tourniquet) is used only when simple and safe methods cannot stop the bleeding, and is used more often when bleeding from an amputated stump.
Victims with temporarily stopped bleeding should be urgently delivered to a surgical hospital in a horizontal position on a shield or stretcher.
First aid for traumatic bruises. In order to prevent hemorrhage, it is necessary to hold the cold at the site of the bruise, provide the affected organ with absolute rest and apply a pressure bandage. In case of bruises of the head, chest, abdomen, accompanied by severe pain and deterioration of the general condition, the victim must be urgently shown to the doctor.
Sprain or damage to the ligamentous apparatus of the joint occurs with sudden impulsive movements in the joint, significantly exceeding the limits of normal mobility in it, or may be the result of a direct blow to a tense tendon.
With a fracture, acute local pain is noted, which increases with the movement of the limb and the load on it along the axis, swelling and an increase in the circumference of the limb segment at the level of the fracture. Absolute signs of a fracture: deformation of the damaged segment and pathological bone mobility.
First aid consists in transport immobilization of the limb, most often with the help of splints made from improvised materials (boards, plywood strips, etc.).
First aid for wounds - protection of wounds from secondary contamination. The surrounding skin around the wound should be smeared twice with an alcoholic solution of iodine and a sterile dressing should be applied, avoiding touching the wound itself. Foreign bodies embedded in tissues should not be removed, as this may increase bleeding. Any washing of the wound is prohibited!
When drowning, the nature of assistance to the victim depends on the severity of his condition. If the victim is conscious, he needs to be calmed, take off his wet clothes, wipe his skin dry, change clothes; if consciousness is absent, but the pulse and breathing are preserved, the victim should be allowed to inhale ammonia, free the chest from tight clothing; to activate breathing, you can use the rhythmic twitching of the tongue.
In case of poisoning, the victim must be laid down with his head raised. Rinse the stomach with 1-2 liters of water, induce vomiting by pressing on the root of the tongue. An unconscious patient is strictly forbidden to wash the stomach. Water can be inhaled and cause death by suffocation. If the victim is not breathing or his breathing is oppressed, it is necessary to perform artificial respiration.
To protect against mechanical injury, the following methods are used:
- unavailability of hazardous objects for humans;
- the use of devices that protect a person from a dangerous object;
- use of personal protective equipment.
There are many ways to ensure the protection of machines, mechanisms, tools. The type of job, size or shape of the material being processed, processing method, location of the work area, production requirements and restrictions help determine the appropriate protection method for a given equipment and tool.
Protective devices must meet the following minimum general requirements:
1) prevent contact. The protective device must prevent the contact of hands or other parts of the body of a person or his clothing with dangerous moving parts of the machine, prevent a person - the operator of the machine or another worker - from bringing his hands and other parts of the body closer to dangerous moving parts;
2) provide security. Workers must not be able to remove or bypass the protective device. Protective and safety devices must be constructed of durable materials that can withstand normal use. They should be securely attached to the machine;
3) protect from falling objects. The protective device must ensure that no object can get into the moving parts of the machine and thereby disable it or ricochet from them and cause injury to someone;
4) not create new dangers. A protective device will not fulfill its purpose if it itself creates at least some danger: a cutting edge, a burr or a surface roughness. The edges of protective devices, for example, must be folded over or fastened so that there are no sharp edges;
5) do not interfere. Safety devices that interfere with work can be removed or ignored by workers.
The greatest application for protection against mechanical injury of machines, mechanisms, tools are protective, safety, braking devices, automatic control and signaling devices, remote control.
Protective devices designed to prevent accidental entry of a person into the danger zone. They are used to isolate moving parts of machines, processing areas of machine tools, presses, impact elements of machines, etc.
Protective devices can be stationary, mobile and portable.
Protective devices can be made in the form of protective covers, doors, visors, barriers, screens.
Protective devices are made of metal, plastic, wood and can be either solid or mesh.
There are four general types of barriers (barriers that prevent entry into hazardous areas).
Stationary fences. Any stationary barrier is a permanent part of this machine and does not depend on moving parts, performing its function. It can be made of sheet metal, wire mesh, slats, plastics and other materials strong enough to withstand any possible impact and have a long service life. Fixed fences are generally preferred over all other types of fences because they are simpler and stronger.
Portable fences are used as temporary during repair and adjustment work.
Guards must be strong enough to withstand the loads from flying particles of the processed material, the destroyed processing tool, from the breakdown of the workpiece, etc.
Entry into the enclosed hazardous area is through doors equipped with interlocks that stop the operation of the equipment when they are opened.
Combined protective devices. The fence is equipped with a locking device. When the guard is open, the locking mechanism will automatically disengage or disengage and the machine cannot continue its cycle or start a new one until the guard is in place. However, replacing the safety device does not automatically turn on the machine. Interlocked guards can use electrical, mechanical, hydraulic or pneumatic power, or a combination of these types of power.
Adjustable safety devices. Adjustable guards allow for flexibility in selecting different material sizes. Such devices are used, for example, on a band saw.
Self-adjusting protective devices. The opening of self-adjusting devices depends on the movement of the material. When a worker advances the material into the danger area, the safety guard swings open, opening up a large enough space just to receive the material. After the material is removed, the fence returns to its original position. Such a protective fence provides protection for the worker by establishing a barrier between them as a dangerous area. It is used, in particular, on woodworking machines and sawmills.
Safety (blocking) devices are designed for automatic shutdown of machines and equipment in case of deviation from the normal mode of operation or if a person enters the danger zone.
Safety devices can stop the machine if a hand or any other part of the body is inadvertently placed in the danger area. There are the following main types of safety devices: presence detection devices and retract devices.
Presence detection devices stop the machine or interrupt the work cycle or operation if the worker is within the danger zone. According to the principle of operation, devices can be photoelectric, electromagnetic (radio frequency), electromechanical, radiation, mechanical. There are other less common types of blocking devices (pneumatic, ultrasonic).
Photoelectric (optical) presence device uses a system of light sources and controls that can interrupt the working cycle of machines. Its work is based on the principle of converting the light flux incident on the photocell into an electrical signal. The danger zone is protected by light rays. Crossing a light beam by a person, his hand or foot causes a change in the photocurrent and activates the mechanisms for protecting or shutting down the installation. Similar optical devices are used in subway turnstiles. Such a device should only be used on machines that can be stopped before the worker reaches the danger area.
RF (capacitive) presence device uses a radio beam that is part of the control circuit. When the capacitive field is broken, the machine stops or does not turn on. Such a device should only be used on machines that can stop before the worker reaches the danger area. To do this, the machine must have a friction clutch or other reliable means of stopping.
Electromechanical device has a trial or contact rod that descends to a predetermined distance from which the operator begins the working cycle of the machine. If there is any obstacle for it to fully lower to the set distance, the control circuit does not start the work cycle.
Work radiation device based on the use of radioactive isotopes. Ionizing radiation directed from the source is captured by a measuring and command device that controls the operation of the relay. When crossing the danger zone, the measuring and commanding device sends a signal to the relay, which breaks the electrical contact and turns off the equipment. The action of isotopes is designed to work for decades, and they do not require special care.
Pulling devices are, in fact, one of the varieties of mechanical blocking. Retraction devices use a series of wires attached to the hands, wrists, and forearms of the worker. They are used primarily in percussion machines. For example, on a small press, when the plunger is at the top, the worker gains access to the area of operation. As soon as the plunger starts to descend, the mechanical connection automatically removes the worker's hands from the operation area.
Emergency shutdown devices. These include: manual emergency shutdown bodies, rods that are sensitive to pressure changes; emergency shutdown devices with a shutdown rod; emergency shutdown wires or cables.
Organs for manual emergency shutdown in the form of rods, rails and wires, which provide a quick shutdown of the machine in an emergency.
Bars sensitive to pressure changes,- when you press them (the worker falls, loses balance or is pulled into the danger zone), the machine turns off. The position of the boom is very important because it must stop the machine before any part of the human body enters the danger zone.
Emergency stop devices with trip rod work by hand pressure. Since they must be switched on by the worker during an emergency, their correct position is very important.
Emergency shutdown wires or cables located along the perimeter or near the danger zone. The worker, in order to stop the machine, must be able to reach the wire with his hand.
Gates are movable barriers that protect the worker from the hazardous technological zone of the machine. The gate automatically closes in every machine cycle before the start of a dangerous technological operation.
Another use of the gate would be as part of a security system around the perimeter of the machine, where the gate protects the worker and those who may be nearby.
Semi-automatic feed. In semi-automatic feeding, the worker uses a mechanism to place the workpiece under the machining tool. There is no need for the worker to reach into the danger zone, since it is completely closed.
Automatic reset. Automatic release can use either air pressure or some mechanical device to remove the machined workpiece from the machine, such as from under a press. An automatic reset can be linked to the operator's control panel to prevent a new operation from starting before the next workpiece is removed.
Semi-automatic reset. It is used, for example, on presses with a mechanical drive. When the plunger leaves the nip, the pick-up arm, which is mechanically coupled to the plunger, ejects the finished part.
Robots. Robots are complex devices that feed and remove material, assemble parts, move objects, or do other work that a worker would do without them. In doing so, they reduce the worker's exposure to danger.
It is better to use robots in high-performance processes that require the repetition of monotonous operations, where they can protect workers from the risks of this production. Robots themselves can create a hazard, and suitable protective devices must be used with them.
Other safety devices. Although the various safety devices do not completely protect against the danger associated with this machine, they can provide workers with additional protection.
warning barriers. Warning barriers do not provide physical protection, they only serve as a reminder to the worker that he is approaching a hazardous area. Warning barriers are not considered reliable protective measures when there is long-term exposure to any hazard.
Screens. Screens can be used to protect against flying particles, chips, fragments, etc. flying out of the processing area.
Holders and clamps. A similar tool is used to place and remove material. A typical application would be when a worker needs to reach out and adjust a workpiece that is in a hazardous area. For this, various kinds of tongs, pincers, tweezers, etc. are used. These tools should not be used as a substitute for other machine guards, but should be considered as merely an addition to the protection provided by other guards.
Rails and strips for pushing material can be used when feeding material into a machine such as a power saw. When it becomes necessary to have hands in close proximity to the saw blade, such a rail or bar can provide additional safety and prevent injury.
Restrictive safety devices- these are elements of mechanisms and machines, designed for destruction (or failure) during overloads. These elements include: shear pins and keys connecting the shaft with the drive, friction clutches that do not transmit movement at high torques, etc. Elements of restrictive safety devices are divided into two groups: elements with automatic restoration of the kinematic chain, after the controlled parameter has returned to normal (for example, friction clutches), and elements with the restoration of the kinematic connection by replacing it (for example, pins and keys).
Brake devices subdivided according to the design into shoe, disk, conical and wedge. Most types of production equipment use shoe and disc brakes. An example of such brakes can be the brakes of automobiles. The principle of operation of the brakes of production equipment is similar. Brakes can be manual (foot), semi-automatic and automatic. Manual ones are activated by the operator of the equipment, and automatic ones - when the speed of movement of the mechanisms of the machines is exceeded or other parameters of the equipment go beyond the permissible limits. In addition, the brakes can be divided according to their purpose into working, reserve, parking and emergency braking.
Application automatic control and alarm devices- the most important condition for the safe and reliable operation of the equipment. Control devices are devices for measuring pressures, temperatures, static and dynamic loads and other parameters that characterize the operation of equipment and machines. The efficiency of their use is significantly increased when combined with signaling systems (sound, light, color, sign or combined). Automatic control and signaling devices are subdivided: by purpose - into information, warning, emergency; according to the method of operation - on automatic and semi-automatic.
The following colors should be used for signaling:
red - forbidding, signals the need for immediate intervention, indicates a device whose operation is dangerous;
yellow - warning, indicates the approach of one of the parameters to the limiting, dangerous values;
green - informing about the normal mode of operation;
blue - signaling, used for technical information about the operation of equipment, etc.
On automated lines, red signal lamps are installed on machines and equipment that are not controlled by service personnel; green - on temporarily non-working equipment.
The type of informative signaling is various kinds of schemes, pointers, inscriptions. The latter explain the purpose of individual elements of machines or indicate the permissible values of loads. As a rule, inscriptions are made directly on the equipment or display located in the service area.
Remote control devices most reliably solve the problem of ensuring safety, because they allow you to control the operation of equipment from areas outside the danger zone. Remote control devices are divided: by design - into stationary and mobile; according to the principle of operation - mechanical, electrical, pneumatic, hydraulic and combined.
Safety signs can be warning, prescriptive and indicative and differ from each other in color and shape. The type of signs is strictly regulated by the state standard.
Ensuring safety when performing work with hand tools. In ensuring labor safety is of great importance workplace organization. When organizing a workplace, it is necessary to ensure:
- convenient design and correct placement of workbenches - free access to workplaces is required, and the area around the workplace must be free at a distance of at least 1 m;
- a rational system for locating tools, fixtures and auxiliary materials at the workplace.
It is advisable to install the workbench on stands, the height of which is selected according to the height of the worker. The workbench must be strong and stable, it is desirable to make its frame metal, welded from corners and pipes. When planning a workplace, you should strive to reduce the number of movements. Movements during the performance of work should be short and not tiring, if possible evenly performed with both hands. To create such conditions, a workbench or table, fixtures, tools, parts must be placed at the workplace, taking into account the following rules:
- all items that are taken only with the right or left hand are placed respectively on the right or left;
- items that are required more often should be closer;
- it is impossible to allow crowding of objects, their dispersion;
- each item must have its permanent place;
- You can not put one item on top of another.
To avoid injury, the following must be observed safety rules:
- when working with cutting and piercing tools, their cutting edges should be directed in the direction opposite to the worker's body in order to avoid injury when the tool breaks off the surface to be treated;
- the fingers holding the workpiece must be at a safe distance from the cutting edges, and the object itself must be securely fixed in a vice or some other clamping device;
- at the workplace, cutting and piercing objects should be located in a conspicuous place, and the workplace itself should be free from foreign and unnecessary objects and tools that can be caught on and tripped over;
- the position of the body of the worker must be stable, it is impossible to be on an unstable and oscillating base;
- when working with a tool that has an electric or any other mechanical drive (electric drills, electric saws, electric planers), you need to be especially careful to strictly follow the safety requirements, because a power tool is a source of severe injuries due to its high speed, for which the speed of human reaction is insufficient to turn off the drive in time at the time of the accident;
- the worker must be dressed in such a way as to prevent parts of clothing from getting on the cutting edge or on the moving parts of the tool (it is especially important that the sleeves of the clothes are buttoned up), because otherwise the hand may be tightened under the cutting tool;
- the mechanized tool is turned on only after the workplace has been prepared, the surface to be treated, and the person has taken a stable position, after the completion of the processing operation, the tool must be turned off;
- when processing brittle materials, a torch of particles is formed, flying out from under the cutting tool at high speed. Particles with high kinetic energy can cause injury, especially eye damage. Therefore, if there are no special protective screens on the tool, the person's face must be protected by a mask, eyes - by glasses, work clothes must be made of dense material;
- when processing a viscous material, chips are formed (metal chips are especially dangerous), they wrap around a rotating tool, and then, under the action of centrifugal force, can fly off and cause injury. Therefore, the resulting band chips must be removed from the tool in a timely manner, after stopping it.
Hand tools can be equipped with additional devices to increase the safety of its use.
To protect a person from mechanical injury, two main methods are used:
1. ensuring the inaccessibility of a person to dangerous areas;
2. the use of devices that protect a person from a dangerous factor.
Means of protection against mechanical injury are divided into:
1. collective;
2. customized.
Means of collective protection are divided into:
1. protective;
2. safety;
3. braking devices;
4. automatic control and alarm devices;
5. remote control devices;
6. safety signs.
Protective devices are designed to prevent accidental entry of a person into the danger zone.
They are used to isolate moving parts of machines, processing areas of machine tools, presses, impact elements of machines, etc. Protective devices can be stationary, mobile and portable; can be made in the form of protective covers, doors, visors, barriers, screens. Protective devices are made of metal, plastic, wood and can be either solid or mesh.
The figure shows a diagram of the robotic area.
Entry into the enclosed hazardous area is through doors equipped with interlocks that stop the operation of the equipment when they are opened.
The working area of cutting tools (saws, milling cutters, cutter heads, etc.) must be closed by an automatically operating fence that opens during the passage of the material being processed or the tool only to let it through.
Guards must be strong enough to withstand the loads from flying particles of the processed material, the destroyed processing tool, from the breakdown of the workpiece, etc. Portable fences are used as temporary during repair and adjustment work.
Safety devices are designed to automatically turn off machines and equipment in case of deviation from the normal mode of operation or when a person enters the danger zone.
They are divided into blocking and restrictive.
Blocking devices exclude the possibility of a person entering the danger zone. According to the principle of operation, blocking devices can be:
1. mechanical;
2. electromechanical;
3. electromagnetic (radio frequency);
4. photovoltaic;
5. radiation.
There are other less common types of blocking devices (pneumatic, ultrasonic).
Photoelectric blocking is widely used, based on the principle of converting the light flux incident on the photocell into an electrical signal. The danger zone is protected by light rays. Crossing a light beam by a person causes a change in the photocurrent and activates the mechanisms for protecting or shutting down the installation. Radiation blocking based on the use of radioactive isotopes finds application. Ionizing radiation directed from the source is captured by a measuring and command device that controls the operation of the relay. When crossing the beam, the measuring and commanding device sends a signal to the relay, which breaks the electrical contact and turns off the equipment. The action of isotopes is designed to work for decades, and they do not require special care.
Restrictive devices- these are elements of mechanisms and machines, designed for destruction (or failure) during overloads. These elements include:
1. shear pins and keys connecting the shaft to the drive.
2. Friction clutches that do not transmit movement at high torques,
3. All kinds of fuses that interrupt the power supply in case of excess loads, etc.
Elements of restrictive safety devices are divided into two groups:
1. elements with automatic restoration of the kinematic chain after the controlled parameter has returned to normal (for example, friction clutches),
2. elements with the restoration of the kinematic connection by replacing it (for example, pins and keys).
Brake devices are divided according to their design into:
1. block,
2. disk,
3. conical,
4. wedge.
Most types of production equipment use shoe and disc brakes. Conical and wedge are used in mechanisms that use the principle of ratchets.
Brakes can be manual (foot), semi-automatic and automatic. Manual ones are activated by the operator of the equipment, and automatic ones - when the speed of movement of the mechanisms of the machines is exceeded or when other parameters of the equipment go beyond the permissible limits. In addition, the brakes can be divided according to their purpose into working, reserve, parking and emergency braking.
Automatic control and alarm devices(information, warning, emergency) are very important to ensure the safe and reliable operation of the equipment. Control devices - these are instruments for measuring pressures, temperatures, static and dynamic loads and other parameters that characterize the operation of equipment and machines. The efficiency of their use is significantly increased when combined with signaling systems (sound, light, color, sign or combined). Automatic control and alarm devices are divided into:
1. by appointment
1.1. informational
1.2. warning
1.3. emergency
2. by way of operation
2.1. automatic
2.2. semi-automatic
The following colors are used for signaling:
1. red - forbidding,
2. yellow - warning,
3. green - notifying,
4. blue - signaling.
The type of informative signaling is various kinds of schemes, pointers, inscriptions. The latter explain the purpose of individual elements of machines, or indicate the permissible values of loads. As a rule, inscriptions are made directly on the equipment or display located in the service area.
Remote control devices(stationary and mobile) most reliably solve the problem of ensuring safety, as they allow you to control the operation of equipment from areas outside the danger zone.
Safety signs can be warning, prescriptive and indicative and differ from each other in color and shape. The type of signs is strictly regulated by GOST.