Snail for ventilation operating principle. Do-it-yourself centrifugal fan snail (photo, video)
Creating high-density airflow is possible in several ways. One of the effective ones is a radial type fan or “snail”. It differs from others not only in shape, but also in its operating principle.
Fan device and design
Sometimes an impeller is not enough for air movement and power unit. In conditions of limited space, a special type of exhaust equipment design should be used. It has a spiral-shaped body that acts as an air channel. You can make it yourself or purchase it already finished model.
To form the flow, the design includes a radial impeller. It connects to the power unit. The wheel blades have a curved shape and create a discharged area when moving. Air (or gas) enters it from the inlet pipe. When moving along the spiral body, the speed at the outlet increases.
Depending on the application, the centrifugal fan volute can be general purpose, heat-resistant or corrosion-resistant. It is also necessary to take into account the amount of air flow created:
- low pressure. Area of application: production workshops, household appliances. The air temperature should not exceed +80°C. Mandatory absence of aggressive environments;
- average pressure value. It is part of exhaust equipment for removing or transporting small fraction materials, sawdust, grain;
- high pressure. Forms an air flow into the fuel combustion zone. Installed in many types of boilers.
The direction of movement of the blades is determined by the design, and, in particular, by the location of the outlet pipe. If it is located on the left side, the rotor should rotate clockwise. The number of blades and their curvature are also taken into account.
For powerful models, you need to make a reliable base with your own hands to secure the body. Industrial installation will vibrate strongly, which can lead to its gradual destruction.
Self-production
First of all, you need to decide functional purpose centrifugal fan. If it is necessary for ventilation of a certain part of the room or equipment, the housing can be made from scrap materials. To complete the boiler, you will need to use heat-resistant steel or make it from stainless steel sheets yourself.
First, the power is calculated and the set of components is determined. The best option The snail will be dismantled from old equipment - an extractor hood or a vacuum cleaner. The advantage of this manufacturing method is the exact match between the power of the power unit and the body parameters. A snail fan can be easily made with your own hands only for some applied purposes in a small home workshop. In other cases, it is recommended to purchase a ready-made model industrial type or take the old one from the car.
Procedure to make a centrifugal fan with your own hands.
- Calculation overall dimensions. If the device will be installed in a confined space, special damper pads are provided to compensate for vibration.
- Manufacturing of the body. In the absence of finished design You can use plastic sheets, steel or plywood. In the latter case Special attention is given to sealing joints.
- Installation diagram of the power unit. It rotates the blades, so you need to choose the type of drive. For small designs, a shaft is used to connect the motor gearbox to the rotor. In powerful installations, a belt type drive is used.
- Fastening elements. If the fan is installed on the outer casing of, for example, a boiler, mounting U-shaped plates are made. With significant power, it will be necessary to make a reliable and massive base.
This general scheme, according to which you can make a functional exhaust centrifugal unit with your own hands. It may change depending on the availability of components. It is important to comply with the housing sealing requirements, as well as ensure reliable protection power unit from possible clogging with dust and debris.
The fan will make a lot of noise during operation. Reducing this will be problematic, since vibration of the housing during the movement of air flows is almost impossible to compensate with your own hands. This is especially true for models made of metal and plastic. Wood can partially reduce background noise, but at the same time it has a short service life.
In the video you can see the process of manufacturing a case from PVC sheets:
Review and comparison of production ready models
When considering a radial fan volute, you need to take into account the material of manufacture: cast aluminum housing, sheet or stainless steel. A model is selected based on specific needs; consider an example of serial models in a cast case.
Depending on the size and performance of such units, operating conditions will also depend: in addition to household 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. General form The input and output channels resemble a snail - hence the name of such a hood.
Attention! Designs of this type are useful in that they can both suck in air and ensure its outflow.
The housing of this type of ventilation system is made of 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 treated with protective paint, chemical-resistant substances, and is 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 placement of the blades ensure high performance of the 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 into 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 expedient to produce homemade snail for 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 wood will quickly catch fire in the event of a malfunction.
The fan in such a system will operate at high speed. Therefore, incorrect design of the hood may 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: V standard models offered in stores, taken into account optimal ratio length and width of the structure;
- if you are not sure what assembled hood 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(outdoors) ensure that weather conditions 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.
The mechanism of any fan is based on a rotor with blades attached to it. Their purpose is to move large masses of air for the purpose of air circulation.
The scope of application of centrifugal fans "snail" is very wide. They are used in building engineering systems, industrial systems ventilation, drying chambers, household appliances, painting, when blowing machines.
The method of creating air flow by rotating a radial wheel with blades in a spiral chamber gave the name to fans - radial or centrifugal. The blades on the wheel can be straight, curved or wing-type.
Air flow pressure, depending on the number and profile of the blades, as well as their rotation speed, divided into three classes:
- low;
- average;
- high.
Pressure indicators fall within the range from 0.1 to 12 kPa. By swapping the phases of the current at the motor terminals, you can change the direction of rotation of the impeller. This is done with a rocker switch on the engine. This is necessary to change the mode of air intake from the room with the injection of clean air.
Design and operating principle
Fan devices used to move various mixtures of gases and air come in several types. The most popular is centrifugal radial unit "snail".
It has a rotating wheel assembly and blades attached to it. Various models fans contain different quantities blades.
The operating principle of the snail hood is as follows:
- Air is sucked into the rotor through the inlet;
- The air mass receives rotational motion;
- Next, by means of the centrifugal force created by the rotating blades, air under pressure is forced to the outlet. It is located in a spiral casing.
Due to the resemblance of the casing to a snail, the fan got its name.
Housing materials
Industrial "snail" may include different materials- depending on the aggressiveness of the application environment. Sheathing of a general-purpose unit operated in non-aggressive gas mixtures with a particle content of less than 0.1 g/cubic meter. m, made from galvanized or carbon steel sheets different thicknesses. If the environment contains aggressive gas mixtures, is characterized by the presence of active gases and the evaporation of acids, corrosion-resistant steels are used. This type of snail fan operates at temperatures up to 200 degrees Celsius.
There is an explosion-proof version of the hood housing. It is assembled from ductile metals: copper or aluminum alloys. Here, during operation of the hood, sparking, which is the main cause of explosions, is eliminated.
Working wheel
Material requirements for impeller with blades- plasticity and protection from corrosion. Then the wheel will withstand vibration loads and chemical influences of the environment. To design the shape and number of blades, aerodynamic loads and rotation speed are taken into account. High rotation speed large quantity slightly curved or straight blades, creates a stable air flow. This creates less noise.
Centrifugal exhaust should be classified as equipment with increased vibration. The reason for the vibration is low level balance of the rotating wheel. Vibration carries with it the following negative factors: destruction of the foundation at the installation site of the equipment and high noise levels. The installation of shock-absorbing springs minimizes vibration. The springs are mounted under the base of the housing. In addition, some models use rubber cushions instead of springs.
Electric motors
Snail-type ventilation equipment is supplied electric motors with explosion-proof covers and housings. A special paint is used to paint engine casings. protective composition. For the most part, these are asynchronous mechanisms with a fixed rotation speed. They are connected to single-phase or three-phase network, depending on the design. In special cases, variable speed motors are used.
Dimensions
The sizes of snail hoods can be different. The diameter of the unit varies from 250 to 1500 mm. “Snails” can represent a single whole or be divided into several parts. In the case of small fans with a solid volute, the rotation angle can be neglected. Simply unscrew the bolts and rotate it to the desired position. Larger models are mostly collapsible. For them, the rotation angle is an important parameter that should be taken into account.
The body of the snail fan resembles the shell of this mollusk. This equipment is used in a number of industrial facilities, housing construction, ventilation systems. The principle of operation is the force created by the rotational movement of the rotor blades; they penetrate into 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 similar type very popular in Lately. However, in the absence of skills and the necessary time, purchasing finished equipment will become one of 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 along a spiral in the outlet hole, the speed increases significantly and creates high pressure. 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.
High pressure equipment - three hundred to two thousand kg/centimeter 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.
The centrifugal fan "snail" requires reliable fastening and solid foundation. 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.
Making the blades yourself, and then high-quality fastening to the rotor is quite a 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 power circuits unit. Power is taken into account here. For high fan power, a belt drive is used. 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. Solid foundation needed for powerful units.
Fans used for air exchange in rooms have different designs. Depending on the operating conditions and assigned tasks, axial or radial devices capable of operating in different modes can be installed. Their purpose and features are optimally suited for a particular section of the ventilation system. Let's take a closer look at the question.
In common parlance called "snail", are devices with multidirectional axes of suction and discharge of air flow. In contrast, where the air stream moves parallel to the axis of rotation of the impeller, centrifugal force is used in the operation of radial fans, which is why such devices called more and centrifugal.
The working body of such a fan most closely resembles a squirrel wheel. The blades, located parallel to the axis of rotation, capture portions of air and, rotating, forcefully push them out in a perpendicular direction. This is the effect of centrifugal force. The fan housing has a specific snail shape, thanks to which all the individual flows ejected by the impeller blades are collected into a single elastic flow rushing outward from the outlet pipe. Because of this, a vacuum is formed, which is immediately filled with outside air entering through the suction hole. It is located on the front side of the case. Thus, it turns out that the suction and discharge of the flow are carried out in a transverse direction to each other.
Peculiarities
The main feature of the cochlear fan is its ability to create high outlet pressure. Axial structures have high performance, but most of them are not capable of creating pressure. Therefore, only “snails” are suitable for working with a complex air duct system with high aerodynamic resistance.
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Based on the amount of pressure created, they are divided into three categories:
Second, no less important feature“snail” fans is the ability not only to create pressure, but also to produce the opposite effect - create a vacuum. This is the versatility of the snail's action - it can equally effectively work both on discharge and on suction. Such capabilities significantly expand the scope of use of snail fans, and, in combination with high operating pressure, allow them to perform additional functions. For example, there are so-called , capable transport bulk materials through the air duct system. In addition, the ability to create negative pressure is used in various industrial technological installations for removing combustion products (exhaust fans).
The most popular models of snail fans are VR and CC (Fan Radial And Fan Centrifugal). Some complication of the situation in this regard is that there are no special rules for naming fans and each manufacturer has the right to name their products as they see fit. Therefore, models of “snail” fans often appear that have exactly the same parameters, but different designations.
Unity of standard sizes is necessary for the possibility of connection to other equipment -, etc. In this regard, the situation is more successful; the fans fit completely into adjacent elements of the system. If models and elements of different standard sizes are used, then appropriate adapters are used to pair them.
Types and scope
Scroll fans have different standard sizes, which allows you to select a device that best suits the operating parameters to the requirements of the system. All samples of “snails” have numbers indicating the diameter of the impeller in decimeters. For example, №5 means that the impeller has 0.5 m in diameter.
The use of "snails" is very widespread. They are found in almost all ventilation systems, in technological lines, used for dust extraction, transportation of bulk products in grain elevators, in woodworking, for removing metal shavings, etc. Widely used as exhaust fans, since there are simply no other structures capable of performing such work.
Expert opinion
Heating and ventilation engineer RSV
Fedorov Maxim Olegovich
A “snail” fan is capable of creating a vacuum in the air duct system covering one or several rooms and thereby organizing the effective exhaust of exhaust air from them.
In addition, the possibility of supplying air ducts to the place where dust directly arises and is emitted is in great demand. harmful substances, suspension. This allows you to quickly remove unwanted components, preventing them from spreading throughout the entire room or building.
Fan VR 100-45 (VTsP 7-40)
As an example of a dust fan used to remove bulk materials or unwanted air suspensions, consider the BP 100-45 fan. Its analogues are the following models: