A low-power centrifugal fan will be of little use. Even quiet hoods are equipped with commutator motors that make a lot of noise. If the fact doesn’t frighten you, let’s proceed to choosing funds. We'll show you how to make a centrifugal fan with your own hands from scrap items. If in a typical axial fan the motor and impeller are important, here, in addition to everything else, the housing is added. Let's try to assemble a centrifugal fan ourselves.
What is a centrifugal fan
A centrifugal fan is used as a duct fan. To make things easier, the vacuum cleaner contains what looks like a duct fan. Now think:
- The dust is sucked up by a hose.
- Passes into the bag (tank, compartment).
- Passes filtration.
- The engine passes.
- Throws out with reverse side housings.
What it does is that there is a centrifugal fan inside, formed by a drum (squirrel cage) mounted on the motor shaft. This is not enough. The engine with the impeller is enclosed in a sealed housing, through the channels of which the air escapes to the outside. Without a tight casing, the meaning of the centrifugal fan will be lost. Here's the main difference. Unlike axial fans, which often serve for personal needs, centrifugal fans are used in the economic sphere: room ventilation, cleaning, air purification. To understand how to make a centrifugal fan, let's study the principle of operation of the device.
Operating principle of a centrifugal fan
A centrifugal fan operates due to the dynamic characteristics of the flow. Try tying a stone to a thread and twisting it around yourself in a horizontal plane. The hand feels a noticeable tension; if the connection were broken, the projectile would immediately fly out tangentially to the circular path of rotation. Air molecules behave similarly: the wheels on the blades acquire significant speed and, unrestrained by anything, are carried away to the outer perimeter. Then the channel system already gives the flow the right direction. Finally, air enters centrally, usually on the side opposite the engine.
Inside the vacuum cleaner we see a picture:
- Air from the bag (tank, container), cleaned of dust, approaches the engine from the front and enters the center of the drum.
- The molecules, accelerated by the blades to a significant speed, are thrown out. They pass through the channels of the sealed housing, simultaneously cooling the engine, and leave the belly of the vacuum cleaner from the back side.
Design feature: the blades of a centrifugal fan create pressure; if the housing is leaky, the air flow will be disrupted. Therefore, the difficulty for a self-taught master is to create the right conditions.
IN good hoods Motors with tangential (centrifugal) type fans are used. In selected designs, the design surprises with a duet of squirrel cages. In the latter case, a pair of impellers is mounted on either side of the engine on a shaft. Then the air enters from two directions perpendicular to the plane of rotation of the wheels. Thus, the efficiency of the centrifugal fan increases.
How to make a centrifugal fan
From what has been said, the obvious way to achieve this is to remove the tangential fan from the hood, for example. Advantage: Silent operation is ensured. The manufacturer complies with the norms prescribed by the standards, so factory-made devices of the hood class are relatively quiet. We believe that for most readers this is not The best decision tasks, let's continue our consideration.
Vacuum cleaner
Inside the vacuum cleaner there is a ready-made centrifugal fan. A big plus is that there is already a ready-made housing that needs to be mounted into the channel on site. TO additional benefits let's include:
The disadvantage of the vacuum cleaner engine is noise. In addition, the commutator motor sparks, which creates interference along the power supply. Will need to do network filter so as not to burn imported home equipment. The noise level is high. Exceeds 63 dB allowed to be produced in an apartment by law.
Washing machine
What else can you use to assemble a centrifugal fan? The image of a front-loading washing machine came to mind. If you remove the door and make channels in the housing so that the flow cools the motor windings, you will get a centrifugal fan. Plus, the working compartment of the washing machine is sealed. Simply remove the tank wall near the engine to create something like a centrifugal fan. The drum will have to be radically redesigned to capture air. The housing will need to be disassembled.
The main dilemma arises: is it worth dismantling the tank? Most models are specially designed so that the operation cannot be performed without damaging the fasteners. It helps service centers track the crafty people doing repairs. In any case, the drum is cut in place to make blades in the walls. Bend the steel inward so that the structure does not touch the tank. Option: from the walls of a steel cylinder, and bend the blades the desired shape in the image and likeness of factory industrial models of centrifugal fans.
The main thing seems to be correct selection speed. 1000 spin rotations is quite enough. The drum diameter is large. The vacuum cleaner produces 6000-16000 rpm, but the radius of the blades is much smaller. Therefore, it is necessary to estimate the linear speed. As you know, the circumference is directly proportional to the radius, therefore, if the diameter of the drum of a Samsung washing machine is 45 cm, it is at least three times larger than that of a vacuum cleaner - equivalent to a speed of 3000 rpm (minimum). But! In this case, the wheel area is much larger, therefore, the flow is enormous.
From the above, we conclude that a speed of 1000 rpm, especially 1500 rpm, is enough to independently make a centrifugal fan from a washing machine. The performance is approximately the same, but the specific flow pressure will be reduced. Much depends on the shape of the blades; we strongly recommend that you inquire on the forum of physicists and hydraulics. The simplest option borrowing a blade from a floor fan. Plastic is welded using a kit plastic bags and a soldering iron, which will strengthen the flywheel on the shaft.
The main thing is to maintain tightness. It is recommended to seal the extra holes that abound in the drum. A homemade centrifugal fan from a washing machine is dangerous to operate (if there are safe tangential fans), it is recommended to close the hatch for loading laundry with a strong grille. For example, make a number of holes on the front side of the case for installing the element. The centrifugal fan device is complemented by a durable fence. Make the grate from a steel rod and fasten it with bolts.
Adjusting the centrifugal fan motor
In 85% of cases the engine is in washing machine collector These, by the way, also work from direct current. The direction of rotation is determined by the polarity of the voltage.
About the speed control scheme. The operating principle of a centrifugal fan requires the use of spin modes. Find the thyristor circuit that regulates the cutoff angle and adjust it as needed. For maximum speed, connect the engine to a 220 V network. We consider the questions of what a centrifugal fan is and how to make one to be answered.
The initial task of any fan is to create a properly directed air flow from a room prone to contamination or the occurrence of high humidity. One of the most effective cleaning systems radial type called hood with unusual name- snail.
Fan “Snail” - an effective cleaning system
Features of the snail hood
The memorable shape and distinctive operating principle make this type of ventilation stand out from similar ones. The most popular snail will be for rooms with a minimum area and free space. The design of the fan in the form of a spiral serves as an air duct in any warehouse or industrial premises.
Factory “snail” units of various configurations are available for your choice, but if you wish, you can build a cleaning system with my own hands is quite real. How to install a snail and why is it better than other cleaning systems? The answers to these questions lie in the structural features of the device.
Snail design
A standard volute (umbrella) consists of an impeller and a power unit. Its own fan, depending on the assigned functions, may have protective properties from corrosion or have increased heat resistance.
The structure of the snail is selected directly for the room in which an additional cleaning system should be installed. When choosing a device, it is recommended to take into account the strength of the air flow, namely:
- low pressure flows;
- average pressure;
- high pressure flows.
When choosing a “Snail” fan, you should take into account the strength of the air flow
Professionals warn that the more powerful the ventilation unit, the more effort should be put into installing it. A homemade box or base will facilitate quick connection and correct operation of the entire device for a long time.
Homemade snail
Before you start creating your homemade system, craftsmen It is recommended to determine the functional purpose of the future device. A centrifugal fan, that is, an umbrella made from simple available materials, is suitable for partial cleaning of premises or complex equipment.
In cases where a do-it-yourself snail fan is intended for boilers, the body of the device must be made of heat-resistant steel sheets. A homemade centrifugal fan is made from old vacuum cleaner parts or cleaning system residential building. Fans such as a snail or an umbrella will serve well in small workshops, but for large-scale enterprises such devices will be of little use.
The entire process of creation and subsequent connection of the fan takes no more than two days, taking into account the fast and quality work at all stages. First, calculate all the parameters of the future device, including the outer box and insulation. It would be a good idea to consider the option of additional gaskets that reduce the vibration effect from the operation of the snail device.
Homemade “Snail” fan is made from improvised materials
Next, the centrifugal fan is assembled from scrap materials or parts of an old device. Suitable for such purposes metal sheets or plastic. Installation of the power unit requires special attention, so at this stage time is devoted to choosing a shaft or drive. The installed cooler will ensure timely cooling of the unit, extending the life of the entire device.
The centrifugal fan is mounted in the outer casing and mounted on a fixed base.
It is within your power to make and then connect using a simple circuit homemade device so-called umbrella, supplement it and equip it with all necessary elements to work in a given room. The main thing is to comply with all the rules fire safety and use the snail for its intended purpose.
One of essential elements production process is the provision comfortable conditions labor. The condition and composition of air masses in any industry often requires adjustment due to dust, release of vapors and gases, excessive humidity, elevated temperatures or toxic impurities. Depending on the features technological process These factors affect not only the health of workers, but also the tightness of the equipment.
Acceptable temperature regime, comfortable humidity and removal of waste air masses contaminated with impurities are provided by the system exhaust ventilation. It should not be confused with the supply air, which is designed to pump Fresh air into the premises, although both of them carry out their functions with the help of special equipment - fans or ejectors.
Exhaust systems using radial or centrifugal fans are widely used in industry.
Exhaust systems using radial fans
Effective and simple devices enjoy deserved popularity in living conditions. Snail hoods, as such fans are otherwise called, quickly cope with eliminating odors, excessive humidity, reducing the temperature in the kitchen, bathroom, garage, basements or in the cellars. Such systems are used, for example, in boiler rooms or apartment buildings.
The figure shows a diagram that ensures the exhaust of air masses using a radial fan.
Design
The ease of assembly and availability of structural elements are the reason why radial fans They are assembled not only in factories, but also at home. After all, industrial assembly, although it has a quality guarantee, is not always available in the price range and in the required configuration for small residential or utility rooms.
The design of a standard centrifugal fan requires the presence of:
- The suction pipe into which the exhaust gas-air masses enter.
- An impeller (turbine) wheel equipped with radial blades. Depending on their purpose, they can be bent forward or backward from the angle of rotation. In the latter option, the bonus will be saving energy consumption by up to 20%. They provide acceleration and also set the direction of air movement.
- A spiral collector pipe or spiral casing, which is why the design is called a snail. It is designed to reduce the speed of air driven through the device.
- Exhaust duct. Due to the different speeds at which the air masses move in the suction pipe and in the spiral casing, quite strong pressure is created here, which can reach up to 30 kPa in industrial conditions.
- Electric motor.
The dimensions of the scroll, engine power, rotation angle and shape of the blades and other features depend on the scope and specific conditions of application.
Operating principle
Efficiency exhaust systems using snails is based on their simple principle of action.
During operation, the electric motor starts the rotation of the impeller.
A turbine wheel with radial blades, thanks to centripetal motion, is sucked through the pipe and imparts acceleration to the gas-air masses.
Their movement is transmitted by the rotational nature of the centrifugal force of the blades. This provides a different vector for incoming and outgoing flows.
As a result, the outgoing flow is directed into the spiral casing. The spiral configuration provides braking and subsequent supply of pressurized flow into the exhaust duct.
From the exhaust duct, gas-air masses are discharged into air ducts for further cleaning and release into the atmosphere.
If the air ducts are equipped with shut-off valves, the radial fan can act as a vacuum pump.
Kinds
The scale of the premises, as well as the level of pollution and heating of the air in them, require the installation of exhaust systems of the appropriate size, power and configuration. Therefore, centrifugal fans come in different types.
Depending on the level of pressure created by air masses in exhaust duct, they are classified into fans:
- Low pressure – up to 1 kPa. Most often, their design provides for wide sheet blades that are bent forward to the suction pipe, with a maximum rotation speed of up to 50 m/s. Their scope of application is mainly ventilation systems. They create less noise, so they can be used in rooms where people are constantly present.
- Medium pressure. In this case, the level of load created by the movement of air masses in the exhaust duct can be in the range from 1 to 3 kPa. Their blades may have different angle and tilt direction (both forward and backward), withstand a maximum speed of up to 80m/s. The scope of application is wider than that of low-pressure fans: they can also be installed in process plants.
- High pressure. This technique is mainly used for technological installations. The total pressure in the exhaust duct is from 3 kPa. The power of the installation creates a peripheral speed of the suction masses of more than 80 m/s. Turbine wheels are equipped exclusively with backward-curved blades.
Pressure is not the only sign by which radial fans are distinguished. Depending on the speed of the air masses, which is provided by the impeller, they are divided into two classes:
- Class I - indicates that frontally curved blades provide a speed of less than 30 m/s, and back-curved blades provide a speed of no more than 50 m/s;
- Class II includes more powerful units: they provide speed to the driven air masses higher than Class I fans.
In addition, the devices are manufactured with in different directions rotation relative to the suction pipe:
- those oriented to the right can be installed by turning the housing clockwise;
- to the left - counterclockwise.
The scope of application of snails largely depends on the electric motor: its power and the method of attachment to the impeller:
- it can gain speed directly on the engine shaft;
- its shaft is connected to the engine using a coupling and fixed by one or two bearings;
- with help V-belt transmission, provided that it is fixed by one or two bearings.
Restrictions on use
It is advisable to install radial fans to move large volumes of gas-air masses, provided that they do not contain:
- explosives;
- fibrous materials and sticky suspensions in quantities of more than 10 mg/m 3 ;
- explosive dust.
An important operating condition is the temperature regime environment: it should not go beyond -40 0 C to +45 0 C. In addition, the composition of the passing gas-air masses should not contain corrosive agents that contribute to the accelerated destruction of the fan flow part.
Of course, for use in some industries, fans are produced with a high degree of corrosion resistance, protection against sparks and temperature changes with casings and internal components made of high-strength alloys.
The body of the snail fan resembles the shell of this mollusk. This equipment is used in a number of industrial facilities, housing construction, and ventilation systems. Operating principle - force generated rotational movement rotor blades, they penetrate the inlet openings in the form of a snail, capture the air flow and drive it through the outlet openings. They are located at an angle of 90 degrees to the entrance hole.
Peculiarities
A good “snail” fan can be obtained with your own hands during the assembly process only if you know the design. The installation and impeller create torque for air movement. Necessity exhaust device increases with limited space, installation occurs with specialized equipment. The fan casing is made in the form of a spiral and serves to direct air.
Homemade fans of this type are very popular in Lately. However, in the absence of skills and the necessary time, purchasing ready-made equipment will be one of the best options.
To create a “snail” in the inner part of the fan mount, you need to place a radial element - a wheel attached to the installation. The discharged space is created by the curved working blades of the wheel.
The air mass enters through the inlet pipe. The inlet pressure drops and draws in ambient air. As a result of the rapid movement of air in a spiral, the speed in the outlet hole increases significantly and high pressure is created. Air flows rapidly from the outlet pipe. If the pipe is on the left, then the rotor rotates clockwise, if on the right, then in the opposite direction.
When assembling with your own hands, the curvature of the “snail” blades used is taken into account.
Created Threads
Centrifugal "snails" - power taken into account in three positions.
Low pressure fans - no higher than one hundred kg/cm square. Temperature no more than 80 °C. Used when equipping production workshops and construction of houses. "Snails" are installed on roofs.
Models with average pressure - from one hundred to three hundred kilograms per square centimeter.
Equipment with high pressure- three hundred to one thousand two hundred kg/centimeters squared. High-pressure air flows from exhaust volutes are usually located in fuel combustion zones different brands in boiler rooms, in fuel and lubricant warehouses, in air duct systems of paint shops.
A centrifugal scroll fan requires reliable mounting and a solid base. In order to avoid vibration, the housing is properly fixed. Ignoring this phenomenon will cause the device to fail.
Do it yourself
The question is rhetorical, which requires the skills of a welder or tinsmith in the process. After all, assembly is carried out from metal sheets of various thicknesses.
Make the blades yourself, and then high-quality fastening to the rotor - quite difficult task. Indeed, if the balancing is imbalanced, the fan will shatter into pieces due to significant rotation of the rotor in the very first minutes of operation.
When assessing power and rotation speed, the electric motor is selected correctly. In this case, craftsmen use snails dismantled from equipment, vacuum cleaners and hoods. This serves as a guarantee for determining the power and parameters of the case.
Assemble the fan a “snail” for household needs in the workshop is possible, it will be a feasible task. In other cases, only factory-made fans are used.
Creation
Instructions for creation.
- Calculate the parameters and dimensions of future equipment. In this case, damper pads are inserted to avoid vibration during operation. These measures will help save the snail.
- Use of available materials in the manufacture of a fan housing made of plastic or plywood. When performing assembly work, make sure once again that there are no gaps and the seams are sealed.
- First you need to analyze the power circuits of the unit. Power is taken into account here. At high power The fan uses a belt drive. At low powers, a shaft and rotor-gearbox connections are used.
- Fastening elements are used, namely plates in the letter “P” for mounting on the body. A strong foundation is needed for powerful units.
Depending on the size and performance of such units, the operating conditions will also depend: in addition to domestic use, many types of ventilation equipment are widely used in the industrial sector. One example of such equipment is a rounded snail hood.
A radial centrifugal fan of this type is most often installed in production premises and is used to clean the air from dust, sawdust, burning, sand and other industrial waste. A similar air treatment system can be installed in multi-storey building, for example, in a ventilation shaft.
Let's understand the principle of its operation and consider the main stages of constructing a snail hood with your own hands.
Design Features
Scroll hoods differ in structure from standard fans with large blades. Air flows in such equipment move due to centrifugal force resulting from the rotation of a wheel with small specially shaped blades. The speed and power of such hoods may vary depending on the number of blades and motor parameters.
The air purification scheme in radial centrifugal hoods is quite simple: when air gets inside the hood, it begins to be sucked into the rotor, where it begins to rotate and is subject to pressure, gradually moving towards the outlet and being cleared of foreign elements. The general shape of the inlet and outlet channels resembles a snail - hence the name of this hood.
Attention! Designs of this type are useful in that they can both suck in air and ensure its outflow.
Frame ventilation system this type is made from durable materials, such as aluminum, brass or steel. Also available for sale plastic structures, but they are less durable and rarely operate at peak efficiency.
Since air treatment can be carried out at high temperatures, the body is processed protective paint, substances resistant to chemicals, and also coated with polymers.
Rotational mechanisms in such a system can be single, or may include two disks with blades required sizes. Both radial and circular blade placement provide high performance device.
Advice: For better cleaning air, purchase fans in which the blades are slightly curved rather than flat.
Despite the uniform shape, such hoods are suitable for many operating conditions, since they differ in orientation to the right or left side, and in overall dimensions. Average the diameter of the main body of such a hood can be from 25 to 150 cm.
For ease of installation for industrial purposes, many structures of this type are created modular, and fastening bolts are used to connect them. Accordingly, you can change both the angle of inclination and the details of some parts of such a design for greater efficiency: It’s better to first calculate all the parameters with specialists.
Since snails can differ from each other, you should not focus solely on size and power ratings. Familiarize yourself with their varieties - and make a choice, relying on future operating conditions.
Types of equipment
First of all, snail hoods differ in pressure indicators. Ventilation can be carried out under the following conditions:
- low pressure – up to 100 kg/m2;
- medium – from 100 dl 300 kg/m2;
- high pressure - more than 300 kg/m2 (can reach 1200 kg/m2).
The first type of hoods is suitable for use in both industrial and domestic environments. As a rule, such equipment is quite compact, so it can be installed without additional help.
Attention! Low-pressure hoods are sufficient to ensure high-quality air ventilation in the shafts of multi-storey buildings.
Medium pressure fans are used for industrial purposes. Such equipment can more easily withstand difficult conditions operation, it is equipped in accordance with the main fire and technical requirements in production.
The third option is used not only in workshops, but also in laboratories, warehouses, areas where painting is carried out, etc. They can be installed for blowing air conditioning systems or working machines, as well as for pumping air in boiler systems.
Depending on the quality and degree of wear of the structure, there are general volute hoods, heat-resistant, corrosion-resistant systems, as well as heavy-duty equipment that can withstand even explosive reactions.
In most cases, snail-shaped air ventilation systems are used to remove pebbles, wood and metal shavings, wood chips and other production residues from the premises. Their installation must be carried out taking into account safety and labor protection requirements.
How to make it yourself
One of the features of such snails is their different price range. The minimum price for a snail hood will be about 3 thousand, but such devices, as a rule, are not very powerful and are very limited in size. The average price of a high-quality unit will exceed 20 thousand rubles.
Therefore, for domestic needs, it is more advisable to make a homemade snail for extractor hood. Standard design such a body will consist of two parts: the engine will be located in one zone, and the blowing blades in the other.
The casing for the snail can be purchased at hardware stores. If you are going to make it yourself, purchase the motor and other parts in advance, since the dimensions will have to be adjusted. It is better to make the case from metals (for example, aluminum and steel). Plastic will be less resistant to mechanical damage, and the tree will quickly catch fire in case of malfunctions.
The fan in such a system will operate at high speed. Therefore, incorrect design of the hood can have bad consequences. Check the quality and reliability of not only the base itself and fastening mechanisms, but also the motor, impeller and fan.
The fan dimensions are selected taking into account the area and degree of contamination of the room. Industrial designs are large.
Important! When installing the motor inside the box of such a hood, make sure that the design includes cooling holes. High temperature stress on the system can lead to an explosion.
Pay special attention to the choice internal materials. Fan operation can be affected not only by temperature, but also by the power of air flow, the amount of debris and dust.
When air with large impurities is sucked in, the blades of the rotating wheel may be damaged. And in order to thoroughly clean the air, the unit must operate at high speed and under high pressure - this creates an additional load on the entire internal structure. That's why it is better to choose parts made of durable materials, such as steel or aluminum.
- choose the right engine size and power: take into account the maximum load on the structure, as well as the required operating speed of the hood;
- When installing such a system vertically, carefully check that the fan and wheel are securely fastened: with rapid air currents they can jump off or change their location;
- materials adjacent to such a hood must be fireproof, like all the parts used in its assembly;
- maintain proportions between individual hood zones: in standard models offered in stores, the optimal ratio of length and width of the structure is taken into account;
- If you are not sure that the assembled hood is safe, contact specialists who will check its serviceability.
note that snail hoods are rarely used in living rooms . Firstly, they take up a lot of space, and secondly, in rooms like a kitchen, the flow of polluted air can have different directions, so it is best to install such a hood in a ventilation shaft, where all the air coming from the apartment is concentrated.
The design of such structures will also play an important role in living rooms, but it is not diverse and does not always harmonize with the interior.
Advice: when placing such a hood in open conditions(outside) make sure weather will not affect its functionality.
Ventilation hoods can be used not only for air purification. In domestic conditions they are excellent cope with heating the room, and also affect the humidity in the room.
The cost of equipment intended for domestic and industrial needs will differ significantly, but, in any case, such units have sufficient power for full operation.
For an example of designing a snail hood, see the attached video.