Abbreviation designation

D 3.5 doors 3 * 1500 Lev. 90 sk. 1 stands for as follows:

- D- smoke exhauster (a device that, by its design, is an industrial fan, in the manufacture of which a thicker metal is used; purpose - operation in high temperature modes);
- 3,5 - 3.5 DM or 350 mm - the size of the impeller, which traditionally affects the size of the entire unit;
- dv... - electric motor;
- 3 - 3 kilowatts, this is exactly the power of the electric motor;
- 1500 - 1500 revolutions (meaning the revolutions of the electric motor shaft);
- Lev.- left (meaning the reversal of the snail);
- 90 - 90 degrees, snail rotation;
- sk. 1- diagram number 1 (design diagram in which the impeller is located on the same shaft with the motor).

The direction of rotation and the angle of rotation of the body (snail) of smoke exhausters, scheme No. 1, view from the side of the electric motor

The scheme of turns of the bodies of type D draft machines of the RIGHT rotation.

The scheme of turning the bodies of draft machines of type D LEFT rotation.

The main elements of smoke exhausters, as well as centrifugal fans, are:

1. A snail is a stationary spiral-shaped casing made of metal, in which vortex flows are created.

2. Impeller. The second name of this element is "squirrel wheel". The rotating part of this element consists of two discs: the central one (in the middle there is a bushing intended for the rotating shaft), open (air intake blades are attached to it, which are bent at a certain angle).

3. Electric motor. It is the main drive for the installation. The smoke exhausters, depending on the recommended operating conditions, are equipped with different types of motors: asynchronous; two-speed asynchronous, allowing to work together with the guide vane, which are distinguished by the efficiency of regulation; single-speed asynchronous type DAZO. In addition, motors can differ in different degrees of explosion hazard, different climatic designs.

4. Frame - a metal supporting frame, which can be modified or absent - it all depends on the specific execution scheme. There are 6 schemes in total: schemes No. 5, 3 and 1 can be executed on a single pedestal with a vibration base or on a single pedestal without vibration generation. However, these ventilation units can also be installed in a non-standard way - depending on the location, project.

Again, depending on the design, the machines can be equipped with a "bearing shaft" (cx. 3), "V-belt transmission" (cx. 5). At the request of the customer and a suitable size, it is possible to complete the assembly with the HA guide vanes.

2. Purpose of smoke exhausters

Smoke exhausters are an important installation in almost all areas of the boiler industry. The latter occupy the main, the main place in the work of the central heating system.

Equipment of this type is installed on large and small stationary hot water and steam boilers. They are suitable for almost all types of boiler rooms. They can also be used to move dust-air mixtures in other technological installations.

DN-type blowing machines are designed to move smoke, dust-gas-air mixtures that are not explosive with a dust content of no more than 2 grams per cubic meter. In simpler, understandable words, such a device is a powerful fan designed to remove combustion products (smoke, steam, fumes) from combustion chambers with a temperature range from minus 30 to plus 200 degrees or up to plus 400 degrees (if is about a new, optimized, improved design). You can learn more about the latter by calling +7 4995023405.

3. Features of the smoke exhauster D

DN-type blowing machines are manufactured in two types - right and left rotation, as evidenced by the corresponding abbreviations in their abbreviations (Pr. And Lev.). In order to determine the direction of rotation, it is necessary to look at the wheel from the engine side: left rotation will occur counterclockwise, right - clockwise. The angle of rotation of the snail ranges from 0 to 270 degrees, while the rotation interval is every 15 degrees. Interfering stiffening ribs of the snail, if necessary, are mechanically modified - trimmed.

Service and inspection of the impellers should be carried out through small special hatches, provided in the wall of the volute. In addition, all snail housings have special buttons for draining condensate.

Large-size bearings (from the impeller side) are installed in Movez smoke exhausters (created according to 5 or 3 schemes), which increases the degree of reliability and durability of the entire product. For such fans, bearing assemblies are made collapsible - this is important for maintainability. In addition, starting from the 9th standard size (i.e. DN 9, etc. to DN 22), it is possible to complete it with a cooling coil (optional; necessary to prevent possible overheating).

A guide vane is used to regulate the operating modes. The latter, by changing the aerodynamic characteristics, increases the efficiency and reduces the energy losses of the installation.

In order to prevent the ingress of large particles that can damage the working parts of the apparatus, suction pockets are used - they retain all solid fractions.

For smoke removal in modern conditions, not only ventilation is used, but also other design options created specifically for these purposes. A smoke exhauster, for example, is a fan that creates a powerful air flow and removes all harmful accumulations from the room.

Scheme of a smoke exhauster-dust collector: 1 - drive shaft, 2 - wheel, 3 - snail of clean gas, 4 - branch pipe, 5 - inlet snail, 6 - additional impeller, 7 - control damper, 8 - cyclone, 9 - branch pipe, 10 - dust gate, 11 - chimney, 12 - bunker.

Today, such devices are used not only in everyday life, but also in industry. They are often used in boiler rooms that run on solid fuels. This is worth talking about, but a little later.

The most important thing is to figure out what such a fan is for and how it works. Today, there are several modifications of it, which differ in characteristics, size and shape. However, despite this, the smoke exhauster device is the same type in any configuration.

The main components of the smoke exhauster

Today the smoke exhauster is a centrifugal fan, which consists of a limited number of parts and assemblies. They all have their own purpose. So, such a fan consists of:

1. Snails. This is a kind of casing, which really resembles this simple insect in its structure. The snail is created in a special way from metal. It is in it that vortex air currents will run. Such a body allows to make the operation of the unit as efficient as possible.
2. Impeller. It is sometimes called the squirrel. Indeed, its design is reminiscent of where this animal runs. Such a wheel consists of two plates. The first fits onto the shaft. A bushing is provided here for these purposes. The second plate is used to fix the blades, that is, the metal plates. They have a certain bend angle, which is done specifically so that the air flow works as efficiently as possible.
3. Electric motor. This element is essential for any fan. This also applies to the smoke exhauster device. A wide variety of engine types are used in industry today. As for the exhauster or fan, it is best to use asynchronous models. They are able to work for a long time from a three-phase power supply network. In addition, such units are not so expensive.

Today it is not difficult to acquire them. They are distributed by many specialty stores. Of course, it is best to use smoke exhausters that have the ability to adjust the rotation of the engine. An asynchronous three-phase motor for these purposes can be equipped with special devices that can have both linear and non-linear characteristics. It all depends directly on the specific case.

Of course, when equipping a fan or smoke exhauster, which has high power ratings, additional protection is required. In this case, the use of an automation system is implied. It is best if a separate circuit breaker is connected to the shield, which, in the event of an unforeseen situation, will turn off the motor.

The electric motor is thus protected from many adverse factors. The machines are selected depending on the power of the motor. Moreover, their current strength should exceed the original exhauster by several percent. These protective devices are used everywhere today. They allow you to save the unit if a short circuit or an open circuit occurs in one of the operating phases.

Back to the table of contents

Some characteristics of the frame

It is most often made of metal. This unit is not standard. If necessary, you can even change its shape in order to easily fix the fan to any base. The frame may not be available.

It all depends on the specific design of the exhauster. They can be mounted in a non-standard way. In this case, everything directly depends on the specific project. There are 6 working schemes in total. Each of them is actively used in practice.

The execution system also affects other components of the unit. They can be additionally equipped with a bearing shaft or a belt drive. Manufacturers often leave the choice of a specific option to the buyer. He, if necessary, can add any working scheme with his innovations.

Back to the table of contents

What is a smoke exhauster for?

So, everything is clear with the fan structure. Now you can talk in more detail about the purpose of the smoke exhauster. In fact, there are several smoke exhausters, because such a device is universal. They are installed in almost all areas of heating systems.

Smoke exhausters occupy a central place in almost all boiler rooms. This is due to their structure and properties. Of course, such units, which have low power, can also be used in industrial plants.

Equipment of this type is installed not only on large, but also on small water heating boilers. They can be used in almost all types of boiler rooms known to mankind. However, the work of smoke exhausters is not limited to this direction. Due to their versatility, they can be used in other sectors of the national economy, where it is necessary to remove smoke from a room or from units.

Back to the table of contents

Features of devices

Basically, all smoke exhausters that are present on the modern market can be produced in two versions, namely right and left rotation. In some situations, it can be difficult to determine where the wheel is turning. However, any specialist is able to cope with this task.

First you need to approach the unit from the engine side. From here it should be visible in which direction the impeller turns. Left rotation is counterclockwise and right rotation is clockwise. The angle of rotation of the snail can be varied. It ranges from 0 to 270 °. The rotation interval is - 15 °.

So, determining the direction of rotation is quite simple. Sometimes there are cases when, during an incorrect connection, the unit starts to work incorrectly, that is, it does not draw smoke from the room, but drives out all the worst from the environment. This is simply unacceptable. This problem can be solved quite simply. It is worth reversing the phases either on the circuit breaker or directly on the engine. That is, you simply need to swap them.

Sometimes stiffening ribs interfere with the operation of smoke exhausters. In this case, some of them can be simply deleted. This is done mechanically.

Visual inspection and maintenance of the units must be carried out through special hatches or openings on the volute. Condensation can accumulate in the fan during operation. Of course, you need to get rid of it immediately. Fortunately, the design of modern units provides for the presence of special drain holes on the snail. Through them, excess moisture is removed.

If large bearings are mounted in the smoke exhauster, then it will serve faithfully for many years.

The wear of such units is insignificant. Collapsible bearings are often used in such exhausters. This is done so that their maintainability is up to the mark. It is quite difficult to work with large units, but if they understand, then this does not arise any problem.

Some smoke exhausters or fans get quite hot. This also applies to large units. In this case, they can be equipped with an additional cooling coil. Today many manufacturing companies offer this additional option.

Fans are an integral part of ventilation, air conditioning and heating systems. They are used both in industrial premises and in residential buildings to provide better air circulation or extract air.

Example of a fan used in an industrial environment

This device is a device consisting of a propeller and an electric motor that drives them. According to the type of installation, they are divided into indoor and roof-mounted. How to determine which direction the blades are spinning? How do I change the side of rotation? How to determine the frequency of the produced revolutions? This is what will be discussed further.

Determination of the side of rotation

It is very easy to determine the side of the impeller movement. The direction of rotation is often marked with an arrow. The arrow indicates the direction in which the impeller rotates. If, for some reason, there is no indication of the direction of movement, then determining the correct side will not be difficult without this.

An example of a "snail" direction indicator

To determine the direction of the blades, it is necessary to look at the structure from the side of the hole through which air is sucked in. If the impeller turns clockwise and the "volute" -type casing is twisted clockwise, the movement is right. If the revolutions of the blades go counterclockwise, the side is left.

How to determine the fan speed?

The frequency of revolutions shows its productivity of the installation. In order to calculate the frequency of movement of the impeller, a device called a tachometer is used. For a more accurate determination, it is recommended to use tachometers of accuracy class 0.5 or 1.

Tachometers differ according to the place of installation and are subdivided into:

• stationary;
• remote;
• manual.

Also, tachometers differ in their principle of operation. They are mechanical, magnetic, magnetic induction and electronic.

Modern electronic tachometer in action

Consider the example shown in the picture. A laser beam directed at the wheel is used to measure the speed (rpm). All data is shown on a small display.

How do I change the direction of rotation of the propeller?

Sometimes there are situations when you need to change the direction of rotation of the blades. For such purposes, reversible fans are used. Their main difference is that the reversible fan is designed for possible changes in direction, while the normal one is not.

Reversible model

Reversible models are widely used in mining enterprises. They serve both to supply air and to extract it.

Reversible axle models used in mines

Changing the side of movement of axial models is carried out in two main ways:

• Without changing the direction of rotation.
• With a change in the direction of rotation.

When using the second method without changing the position of the blades, the system does not work at full strength. The wheel runs backwards forwards, which leads to a decrease in efficiency. In order to get 100% performance in reverse, it is necessary to change the position of the blades.

In order to change the direction of rotation of the propeller, it is necessary to disassemble the engine and change the phases:

• On a single-phase motor, we have 4 wires at the output. 2 wires at the beginning of the winding and 2 at the end. For reverse, it is necessary to flip the phase and zero from the beginning of the winding to the end.
• In the case of a three-phase motor, we have 6 wires at the output. 3 at the beginning of the winding and 3 at its end. To reverse in a three-phase network, we need to swap any two wires at the input.
• To reverse a three-phase electric motor connected to a single-phase network through a starting capacitor, it is necessary to swap the cable that goes to the input of the capacitor with a cable that is not connected to it.

In order to change the direction of travel of the propeller of an exhaust hood (kitchen hood), there are two operating methods:

1. If an asynchronous electric motor is installed in the hood design, the change is made by throwing the wires (the method is described above).
2. In the case of a phase-shifting capacitor, the change is made by rearranging it. For the correct execution of this method, it is recommended to contact the services of an experienced electrician.

Exhaust hood

Summarize. The direction of travel of the wheel is determined either by the arrow drawn on the housing or impeller, or by looking from the side.

A device called a tachometer is used to measure the speed of the blades. They are both old mechanical and modern, reading information using a laser beam.

To change the direction of rotation of the blades, we just need to change the necessary contacts on the electric motor. If, after changing the side of the direction, it is not possible to change the position of the blades, then the efficiency and its productivity will drop by about 30% of the norm (depending on the type).

All these procedures can be performed without much effort and with your own hands.

It is very easy to determine the direction of rotation of the fan volute. You need to look at the fan from the suction side (as shown in the figure and in the photo). If the impeller rotates clockwise and, accordingly, the "volute" body is also twisted clockwise, then the direction of rotation is right. If counterclockwise - left. The angle of rotation is also easy to determine - the position of the outlet is taken as the starting point, vertically upward, this is zero degrees. Further, clockwise for the right and counterclockwise for the left, with a multiplicity of forty-five degrees, the angles of the snail's turn are counted. You should be aware that this definition of rotation is typical for general industrial fans. For example, for smoke exhausters and draft fans, the opposite is true! Be very careful when determining the direction of rotation. If you are in doubt about the exact determination of the direction of rotation of your fan - consult our managers!
The direction of rotation of the impeller determines the "twist" of the fan volute casing, it can be right-handed or left-handed. Which direction is considered right and which is left is shown in the figure below.

The direction of rotation of the fan is very important to choose correctly, since a fan of a certain direction of rotation and angle of rotation is mounted in the ventilation system. For small units, the direction of rotation may be unimportant; the angle of rotation of the volute is set when the fan is installed in the ventilation system. The larger the fan, the more important is the direction of rotation and the angle of rotation of the snail, since the snail of a large fan consists of two or more parts, installation and dismantling of the snail with an incorrect angle of rotation will be difficult, and in some ventilation systems it is impossible. The snail of a large unit consists of several parts, not only for ease of transportation, but also for ease of maintenance. The volute is undocked in such a way that during the assembly / disassembly of the machine it is possible to first install a part of the housing on the foundation, then install the impeller, and then put the second part of the volute. Thus, to replace the impeller, a complete dismantling is also not required; it is enough to remove only one part of the volute casing.

see also.