Coil fans: radial, centrifugal and exhaust. Circulation pumps, volutes Review and comparison of production ready models

In ancient times, now I don’t even remember when, I had inflatable boat produced by the Ufa Inflatable Submarine Plant. It was called that - Ufimka 22. Two oars for two, two compartments, two valves; in general, the boat was not bad. I also repaired it twice before giving it to someone for further torment (thus, there were also two owners).

In ancient times, now I don’t even remember when, I had an inflatable boat produced by the Ufa Inflatable Boat Plant. It was called that - Ufimka 22. Two oars for two, two compartments, two valves; in general, the boat was not bad. I also repaired it twice before giving it to someone for further torment (thus, there were also two owners).

And in the same ancient times, only a little less ancient, I got an Intex pump, along with an air mattress. But the mattress, as usual, did not stay with me for a long time - this is the property of these mattresses, well, we are not talking about a mattress.

That pump was powered by a cigarette lighter, had several batteries on board for autonomy, and was almost immediately adapted for inflating the boat. I remember being terribly proud and pleased with my ingenuity, not suspecting that I had invented the wheel.

Since then, three boats have changed, and all were pumped with this pump, with further finishing with a foot pump.

Contrary to the design, the pump was disassembled and repaired a couple of times, the adhesive seam was carefully wrapped with red electrical tape, the bearings were lubricated, and when pumping, the turbo mode was turned on - I started the car engine, 14 volts entered the pump, and it howled even more angrily and performed miracles of performance. The main disadvantage was that there was not enough air flow to overcome the valve spring. Therefore, I opened the valve, pumped up the compartment, closed the valve with a swift movement practiced hundreds of times, and pumped it up with a foot pump. It seems that the amount of air that this pump passed through itself would be enough to fill an airship with the "M" nameplate.

You know, there are things that you have been using for a long time, you are extremely tired of them, but to use something else - it’s not that it doesn’t occur to you, but you don’t have the determination. As a rule, this lasts until the moment you ask yourself with all directness and decisiveness: “What, exactly, is happening?” At one point, that’s exactly what happened.

One more nuance: the boat I have now is Skif. This is such a small inflatable pie that either children or very unpretentious and balanced people who have reached the heights of self-improvement and self-knowledge can afford to sit in together. What I mean is that the boat, to be honest, is a single-seater, and when one day, succumbing to persuasion, I made an attempt to fish together, within a couple of minutes I was ready to kill.

Buying a serious two-stage pump for such a liner is undoubtedly a quick path to fame, but for some reason this kind of fame did not appeal to me.

Thus, I chose from the class of pumps, which are popularly called “snails”. The choice between the two models ended without beginning with the victory of the Bravo MB 80C pump. And not because it’s red, but because it’s powerful: 700 liters per minute. For a rich imagination there is room for fantasy, but for me it’s about pumping up the boat.

I’ll say right away that I was pleased with the pump. The snail turned out to be a racing snail, a champion among snails. If earlier, by connecting the pump to the boat valve or air mattress, I had a lot of free time at my disposal, I was leisurely, and, one might say, imposing, but now it turned out to be absolutely impossible to be distracted by anything else. Don't think I'm complaining now. Having quickly figured out the adapters that came with the kit, I was surprised when I turned on the pump and the boat jumped straight out of its deflated position.

Just as quickly, the pump pumped the air out of the boat at the end of fishing. Then there was a trip to nature, I wandered around the camp and, like a magician, shook mattresses in front of a stunned audience. There was a queue for downloading.

This is such a wonderful pump, a turbo snail, an air conqueror. Now that the pump has become even redder, but already from praise, let's move on to the shortcomings and improvements.

It has two disadvantages, In my opinion.
1. The adapter hose is terrible, it is shamelessly short and just as shamelessly thin in the wall. It crumples and falls off, there’s nothing to add. The problem was solved after the first fishing: half a meter of thick rubber hose.

2. No cover. The box is not even considered as a shipping unit. The adapters crumble and tend to escape into the grass, where it is thicker. A fabric cover is what the voice of reason calls for. While he is calling, the pump has taken root in a bucket with different zips to the motor. That's all for now, I don't want to find fault.

I don’t know how long this miracle will work, it’s too early to draw conclusions about reliability, but the price seems to hint that a “once a season” purchase cannot ruin you in principle. On at the moment I am more than satisfied; An excellent purchase, I think so. Yes, and after that trip to nature I ordered another pump, but not for myself. UPD: Already two.

A snail fan is one of the most popular devices that are used to create air flow with high densities. This hood has its own characteristics, design nuances and operating principle that distinguishes the snail from other systems.

Before you assemble a highly efficient snail fan with your own hands, you should find out about the features of this device and its design.

To carry out forced air movement, sometimes you can get by with an impeller and a power unit that will rotate the working element;
If space is limited, but an exhaust unit is absolutely necessary, specialized equipment comes to the rescue;
The cochlea is a body made in the form of a spiral;
The mission of the corps is to carry out the tasks of the air channel;
Do-it-yourself snails are quite popular, but when there is no time to assemble or lack the appropriate skills, objectively the best solution will be the purchase of finished equipment;
To create an air flow, a radial component - a wheel - is located inside the fan structure;
This radial piece of equipment connects to the power plant;
The blades on the impeller are curved, which allows them to create a discharged area when they move;
The inlet pipe of the structure serves to supply air or another medium;
Due to the movement along the spiral casing, the speed of air exiting through the outlet opening increases noticeably;
Snail fans come in heat-resistant, corrosion-resistant and general purpose;
The movement of the volute fan blades depends on the design of the equipment. Particular attention should be paid to the location of the outlet pipe. If it is on the left, then the rotor should rotate clockwise, or vice versa;
When choosing or assembling a snail with your own hands, you need to take into account how many blades are used and what their curvature is.

Created air flows

When planning to assemble a homemade unit with your own hands or buy a ready-made snail-type exhaust apparatus, you should definitely take into account the characteristics of the air flows created. Namely, you should be interested in the flow value, on which the scope of application of the snail largely depends.

Low pressure. Air currents low pressure are widely used in equipping production workshops and assembling household appliances. The air temperature here is not allowed to exceed 80 degrees Celsius. Also, low-pressure snails are not adapted to work in aggressive environments.
Average pressure. Medium-pressure scroll fans are most often found in the design of an exhaust system used for transportation and removal of fine materials. A striking example is grain and sawdust removal.
High blood pressure. Snail hoods high pressure form air flows that enter the combustion zones various types fuel. Boiler equipment, working on different types fuel, is equipped with high-pressure volutes.

Snail, or centrifugal fan, requires a reliable foundation. The housing must be properly fixed so as not to create vibration. Industrial units characterized by increased vibration. If this phenomenon is not prevented, the device will gradually fail.

Do it yourself

Building a scroll fan is not the most difficult thing if you decide to take on a homemade unit with your own hands.

Functional purpose. To equip a part of the room with a ventilation system, small area or equipment, the housing can be assembled from scrap materials. If this centrifugal unit, which will generate air flows to ensure the operation of the boiler equipment, then the body is made by hand based on stainless steel or heat-resistant metal.
Power. This parameter directly depends on the functions that the centrifugal unit will perform. Many home craftsmen use snails removed from old equipment, ventilation systems, hoods or vacuum cleaners. By using such a unit, you guarantee an exact balance between power and body characteristics.

If you want to make a snail for household use, use inside the workshop, then you can assemble the device yourself. All other situations imply the need to use only factory-proven, proven snails.

To assemble an effective homemade snail fan with your own hands, you will need to complete the following tasks:

Calculate the dimensions of future equipment. If this is a centrifugal unit for installation in a confined space, be sure to use damper pads. They will compensate for the vibrations generated during its operation and protect the volute from premature wear. If this is a large stationary unit, vibration protection occurs due to the weight of the equipment and its fixation;
Make a fan casing. If you do not have a ready-made box that is ideal for the fan, use improvised materials. Plastic, plywood sheets, and steel are suitable for these purposes. If you decide to take sheets of plywood, make sure that during the process of assembling the structure there are absolutely no gaps and all seams are properly sealed;
Think over the diagram of the snail's power unit. The job of the power plant is to rotate the fan blades. When choosing, consider how much power the snail has. If it is a high power centrifugal fan, use a belt drive. In small installations, it is important to use a shaft that connects the motor gearbox to the rotor;
Use fasteners. When installing a scroll fan on the outer casing of the structure, use U-shaped mounting plates. If the power of the units is impressive, then be sure to adopt a massive, durable base;
Minimize noise. A high-power volute is characterized by the fact that such a centrifugal fan emits quite a lot of noise. Objectively best way protect yourself from snail noise by assembling the equipment as efficiently as possible. After assembling the cochlea, it is problematic to compensate for the noise. The noisiest models are those whose body is made of plastic and metal. Wooden cases reduce snail noise, but are significantly inferior to their metal and plastic counterparts in terms of service life.

According to the presented diagram, you can create centrifugal exhaust devices of various power purposes with your own hands. If necessary, you can make changes to the circuit, change components, add auxiliary elements.

The most significant point when assembling a fan with your own hands is the reliable sealing of all seams in the structure and the protection of the engine itself. Over time and with use, an engine that does not have proper protection can become exposed to various debris, dust, dirt and moisture. It is no secret that this leads to wear, gradual destruction and failure of equipment.

One of essential elements production process is to ensure comfortable working conditions. 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 these fans are otherwise called, quickly eliminate odors, excess humidity, and reduce temperatures in the kitchen, bathroom, garage, basement or cellar. 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 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. Because of different speeds, with which the air masses move in the suction pipe and in the spiral casing, a fairly 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 air ducts are equipped with shut-off valves, then radial fan can work as a vacuum pump.

Species

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 the air masses in the 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. The scope of their 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 can have different angles and tilt directions (both forward and backward), and can withstand maximum speed 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 blood 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 different directions of 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 the 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.

Creating air flow with high density 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 and a power unit are not enough to move air. 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 a ready-made model.

To form a flow, the design provides 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. Scope 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. The industrial installation will vibrate strongly, which may 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 structures, 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 requirements for sealing the housing, as well as to ensure reliable protection of the 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.