How does a membrane work. How does a membrane expansion tank work. How to install a membrane tank

An autonomous water supply system today no longer surprises anyone. Such designs are very convenient and practical, however, their operation often requires devices that a person using only centralized water supply may simply not know about. For example, an autonomous water supply system will work uninterruptedly for a long time only if it includes expansion tank for water supply. Modern industry produces many of the most different models such devices. To choose for yourself best option, you need to navigate the types of equipment and have a good idea of ​​\u200b\u200bthe principle of its operation.

The device and functions of this equipment

Types of membrane tanks

There are two main types of expansion membrane equipment.

Membrane instrument

home distinguishing feature- the possibility of replacing the membrane. It is removed through a special flange, which is held on by several bolts. At the same time, it should be taken into account that in large-volume devices, to stabilize the membrane, it is additionally fixed back to the nipple. Another feature of the device is that the water filling the tank remains inside the membrane and does not come into contact with the inside of the tank. That protects metal surfaces from corrosion, and the water itself from possible contamination and significantly extends the life of the equipment. Models are available in both horizontal and vertical versions.

Devices with a replaceable membrane differ more long term service, since the most vulnerable element of the system can be replaced and water does not come into contact with the metal case of the device

Stationary Diaphragm Device

In such devices inner part The tank is divided into two parts by a rigidly fixed membrane. It cannot be replaced, therefore, if it fails, the equipment will have to be changed. One part of the device contains air, the other contains water, which is in direct contact with the internal metal surface device, which can provoke its rapid corrosion. To prevent metal destruction and water pollution, the inner surface of the water part of the tank is covered with a special paint. However, this protection is not always durable. Devices of horizontal and vertical types are issued.

A type of device with a rigidly fixed membrane. The design assumes that water is in contact with the walls of the equipment

In our following material the expert's recommendations on the choice of a membrane tank are presented:

How to choose the right device?

The main characteristic on the basis of which equipment is selected is its volume. In this case, the following factors must be taken into account:

• Number of people using the water supply system.
• The number of water intake points, which include not only showers and taps, but also Appliances such as washing machines and dishwashers.
• The probability that water will be consumed by several consumers at the same time.
• The maximum number of start-stop cycles per hour for installed pumping equipment.

• If the number of consumers does not exceed three people, and installed pump has a capacity of up to 2 cu. m per hour, a tank with a volume of 20 to 24 liters is selected.
• If the number of consumers is from four to eight people and the pump capacity is within 3.5 cubic meters. m per hour, a tank with a volume of 50 liters is installed.
• If the number of consumers is more than ten people and the performance of pumping equipment is 5 cubic meters. m per hour, choose an expansion tank of 100 liters.

When selecting desired model devices, it should be borne in mind that the smaller the volume of the tank, the more often the pump will turn on. As well as the fact that the smaller the volume, the greater the likelihood of pressure surges in the system. In addition, the equipment is also a reservoir for storing a certain supply of water. Based on this, the volume of the expansion tank is also adjusted. You should be aware that the design of the device allows the installation of an additional tank. Moreover, this can be done during the operation of the main equipment without labor-intensive dismantling. After installation of a new device, the volume of the tank will be determined by the total volume of the tanks installed in the system.

Except specifications choosing an expansion tank, Special attention you should contact its manufacturer. The pursuit of cheapness can result in much more significant costs. Most often, the cheapest materials are used to produce models that attract with their cost, and, as practice shows, they are not always of high quality. The quality of the rubber from which the membrane is made is especially important. Not only the service life of the tank directly depends on this, but also the safety of the water that comes from it.

When buying a tank with a replaceable membrane, be sure to clarify the cost of the consumable item. Very often, in the pursuit of profit, not always conscientious manufacturers significantly overestimate the price of a replacement membrane. In this case, it would be more appropriate to choose a model from another company. Most often, a large manufacturer is ready to be responsible for the quality of its products, since it values ​​its reputation. Thus, it is worth considering the models of just such brands in the first place. These are Dzhileks and Elbi (Russia) and Reflex, Zilmet, Aquasystem (Germany).

The volume of the expansion tank for water supply can be different, it is selected based on the needs of users. If a larger volume is subsequently required, an additional device can be installed

Features of self-installation

All expansion tanks can be divided into two groups, determined by the connection method. There are vertical and horizontal models. There are no particular differences between them. When choosing, they are guided by the parameters of the room where the equipment will be placed. During the installation process, the following recommendations should be followed:

• The expansion tank is installed in such a way that it can be easily accessed for maintenance.
• It is necessary to provide for a possible subsequent dismantling connecting pipeline to replace or repair equipment.
• The diameter of the connected water supply can not be less than the diameter of the branch pipe.
• It is necessary to ground the device, so electrolytic corrosion can be avoided.

The device is mounted on the suction side of the pump. On the segment between pumping equipment and the connection point must exclude all elements that can make a significant hydraulic resistance into the system. We connect the make-up line to the circulation circuit of the entire system.

According to the type of installation, expansion tanks of horizontal and vertical connection are distinguished

Also pay attention to the material on what malfunctions most often occur in pumping stations, and how to fix them yourself:

Expansion tank is an integral part autonomous system water supply. It supports, prevents premature damage to the pump and retains a certain supply of water. However, all these functions are performed only under the condition of competent selection and proper installation of the structure. Therefore, in the absence of experience, it is better not to get involved in amateur performances, but to find qualified specialists who will install any device with high quality.

What is it needed for membrane tank for water supply? When organizing an autonomous water supply for a private house from wells or wells, it is necessary to create an emergency supply of water. An expansion tank for water supply is perfect for these purposes. These containers are practical, have a large volume, but to ensure a normal operating mode, it is necessary to use a number of devices, and not be limited to just one installation.

When a tank is included in the water supply system, the autonomy of water supply is significantly increased. The created reserve will allow solving problems with water supply that may arise during and during the operational care for equipment and wells. On the this moment industry produces a huge amount various models which greatly complicates the choice.

An expansion tank for water supply is used to maintain the desired pressure level when autonomous water supply. Most often, membrane (expansion tanks) are used for these purposes. These are containers, inside of which there are rubber membranes that divide the tank into chambers. One chamber is water, the other is air.

The tank is connected to the water supply of an autonomous water supply system so that the inlet branch supplies water to the tank, filling it, and only after filling a certain volume, water is supplied to consumers.

The principle of operation is as follows: when the system is turned on (started), the pump pumps into water chamber water until it is full. In this case, the volume of the second chamber is significantly reduced. When the air chamber is reduced, the amount of air inside it does not change, so the pressure on the membrane increases. Accordingly, the pressure in the system increases.

Expansion tanks use a membrane that separates it into 2 reservoirs, one with air and the other with liquid. In this case, it is necessary to have pressure control equipment (pressure switch) in the tank. This is necessary for automatic shutdown pump, the same sensor automatically starts the pump when the pressure in the tank drops below the programmed value. This will allow automatic operation the entire water supply system.

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However, it is worth remembering that a smaller volume allows you to reduce pressure drops in the system. At the same time, the tank itself is a reserve tank for storing water.

Membrane tissue is innovative material with selective permeability. Has elevated protective properties. Used for the production of children's, sportswear, equipment of adherents of active winter recreation, representatives of extreme professions.

Why are membranes needed?

The word "membrane" ancient origin and means "membrane". AT old times it was applied in the ordinary and biological sense. As science developed, the term acquired physical, chemical, technical significance. Membrane technologies are now used in light industry for the production of clothing.

One of the main functions of clothing is protective. Previously used to protect against rain rubber shoes, polyethylene raincoats, capes from others. From rain, snow, wind, these materials protected well for some period of time. It is impossible to stay in waterproof products made according to old technologies for a long time.

The human body, on average, releases more than half a liter of moisture per day, which accumulates on clothes from the inside if there is no way out. With active movements, the amount of sweat released can reach one and a half liters.

The introduction of membranes into the composition of protective fabrics allows you to remove water vapor, while preventing moisture, wind, rain, snow from getting inside.

The structure and mechanism of action of membranes

The simplest example of a membrane product is a plastic bag (not to be confused with polyethylene). If you pour, for example, a salted protein solution into a plastic bag and hang it in a container with clean water, then after a while the salt will penetrate through the pores of the cellophane into the water. Cellophane selectively lets small molecules out, retains large ones inside, water molecules from the outside do not seep into the bag.

The membrane layer in tissues works in a similar way. It lets small molecules out without letting anything in.

Membranes used in light industry are usually divided into porous (containing pores) and non-porous (supposedly not containing pores). The division is conditional, but widespread. It is advisable to use it.

• Membranes with pores are thin polymer layers with very small holes through which gaseous water (steam) molecules can seep from the inside, but drops do not fit there. Recall the course of the school: in a drop, water molecules “stick together” - they are in the form of associated groups. In the vapor state, water molecules are alone, the distance between them does not allow them to unite. The American company Gore-TeX makes membrane fabrics from Teflon, for 1 cm 2 of which there are about one and a half billion micro-holes - pores.
• Membranes without pores act differently. They also contain many microcells with a complex, sinuous shape, reminiscent of the structure of a sponge. The steam from the skin is absorbed into the cells, saturates the membrane, turns into condensed moisture and, due to the difference in partial pressure (this concept is also from school courses), is released to the outside. This principle of separation is possible because there are more vapors inside than outside. If, hypothetically, the wearer of the clothing enters a sauna or other room with very high humidity, the moisture will enter in the same way.

In some materials, different membranes are combined, a layer without pores is laid on the outside, and with pores on the inside. The fabric is effective but expensive.

Comparison of terms of use

• All membrane tissues remove vapors from the area high blood pressure to the zone reduced pressure(as the value gradient experts say).
• At high humidity, membranes with pores are better able to remove vapors to the outside, especially if there is ventilation on clothing. Non-porous membranes are effective in relatively dry air environments. If humidity is high or ventilation is open, such a membrane will not work well.
• At low temperatures the membrane with pores works better. At negative temperatures of the material, pore-free membranes simply freeze.
• A porous membrane may become clogged if not properly cared for or worn. Poreless membrane fabrics are durable and last a long time.

Main characteristics

Membrane fabrics are designed to protect against the weather and create a sense of comfort for wearers. Functions justify the importance of key indicators.

• Waterproof. At high pressures of the water column, any tissue will begin to leak. For successful operation, the values ​​of the maximum tolerable impacts are important. Clothing designed for tough conditions must withstand pressures of 20,000 mm of water column and above. A value of 10000 mm is acceptable for normal rainy conditions.
• Vapor permeability characterizes the mass of steam in grams, which can be removed by 1 m 2 of material in a given unit of time (usually 24 hours). The most common minimum vapor permeability is 3000 g/m2, the maximum is from 10000 g/m2. Sometimes this property is measured by the ability to resist steam transport (RET). If this indicator is equal to 0, the fabric completely passes all the steam, with a value of 30, the passage of steam is practically excluded.

The membrane does not perform insulating functions. It saves from rain, wind, snow, provides "breathing" to the body, helps to provide thermal comfort.

Fabric structure

Structurally, membrane fabrics differ in execution.

• In bilayer tissues, the membrane is fixed with inside canvases. Additionally, it is closed with a lining that protects against damage and clogging.
• In three-layer fabrics, the following are glued together: the outer layer, the membrane, inner mesh. The need for a lining layer is eliminated. The material is very comfortable, it is more expensive.
• In some modifications, a special protective coating is sprayed on the inner surface of the two-layer fabric.
• There are types of membrane fabrics with a water-repellent layer (DWR) applied on top. The coating may wash off over time. It is easily restored by special means.

Leading manufacturers

The most authoritative, historically the first manufacturer of membrane fabrics is Gore-TeX. She made clothes for astronauts. Then several types of products were offered to skiers, climbers, mountain tourists.

Clothing with Triple-Point, Sympatex, ULTREX membranes is comparable in quality. The material is solid, available in several versions. The price is high, corresponds to the properties of the products.

Products with Ceplex, Fine-Tex membranes have an affordable price. It is designed for a maximum of 2 seasons of active wear, after which the material may begin to let water through a little.

When buying clothes made of membrane fabrics, pay attention to the information about gluing the seams. In some varieties, absolutely all seams are glued, in others - only the main ones. For wearing in the city, gluing the main seams is enough. For active sports, it may be better to choose products with all reinforced seams. The choice is up to the potential wearer.

Rules for the care of membrane tissues

The material is specific in composition and structure. Normal washing methods should not be applied to this group of products.

• You can wash the fabric with a membrane layer in the machine using a gentle mode and soft special products.
• You can't push in the car.
• You can't take it to the dry cleaners.
• Ironing is not necessary, it is not necessary to do this.
• Can be washed by hand if desired.
• You can leave the thing in an arbitrary straightened state so that water flows from it.
• The fabric is very slightly soiled. After wearing, drying, it can be lightly brushed with a regular brush.

Fabrics with membrane materials allow you to feel protected in any bad weather with the most active activities.

At the present time, as a compensating device for the coolant, a membrane expansion tank has gained great popularity. Gravity heating systems with natural circulation are rarely used, and therefore open containers are gradually becoming a thing of the past. Such devices are needed modern systems water supply, where pumping stations and boilers are installed indirect heating. This material will tell you how to choose and connect such a tank to a particular system.

The device and principle of operation of the membrane tank

Let's start with the fact that structurally devices designed for heating and water supply (hydraulic accumulators) have some differences and cannot be confused with each other. At the same time, the principle of operation of a membrane tank is the same regardless of its design.

The general arrangement of such tanks is as follows: inside a sealed metal case cylindrical shape there is a rubber membrane (popularly - "pear"). It is of two types:

• diaphragm that separates inner space approximately in half;
• in the form of a pear, with its base attached to the water inlet.

Note. The second type of membranes must be replaced, for this it is necessary to unwind the flange of the pipe. The first type cannot be replaced, only together with the body.

The difference between vessels for different systems consists in the fact that membrane expansion tanks for heating systems are filled with a coolant that comes into contact with the metal walls from the inside. In water supply tanks, water never comes into contact with metal, and some models even provide for flushing the “pear”. These modifications are recommended for use in drinking water supply networks.

Another difference is that membranes for water expansion tanks are made:

• from food rubber;
• adapted to a higher pressure than for heating.

Accordingly, the "pear" in the tank for heating systems is adapted to work at more high temperature. The very principle of operation of the devices is simple: under the influence of external forces (thermal expansion or the action of a pump), the container is filled with water and stretches the membrane to known limits. An increase in the "pear" on the other hand limits the air under a certain pressure. To create this pressure, the tank device provides a special spool.

When the external influence stops and the pressure in the pipeline network drops due to water intake or cooling of the coolant, the membrane gradually pushes water back into the system.

Let's start with the fact that a membrane expansion tank for water supply cannot be used in heating networks and vice versa. The reason is that each of the systems has its own pressure and temperature, as well as requirements for water quality. Meanwhile, they are outwardly very similar, manufacturers even manage to paint the tank bodies in one color (most often red). How to distinguish?

Each product has a nameplate attached to it. It contains all the information we need. When the nameplate says that the maximum operating pressure is 10 Bar, and the temperature is 70 ºС, then in front of you is an expansion tank for cold water supply. If the inscription says that the maximum temperature is 120 ºС, and the pressure is 3 Bar, then this is a membrane tank for heating, everything is simple.

The second selection criterion is the volume of the tank, it is determined as follows:

• for heating system: the total amount of coolant in the house network is calculated and a tenth is taken from it. This will be the capacity of the tank with a margin;
• for water supply: here the volume of the vessel should ensure comfortable operation of the water pump. The latter should not turn on and off more than 50 times per hour. A sales representative will help you determine the figure more precisely;
• for hot water supply (tank for a boiler). The principle is the same as with heating, only you need to take a tenth of the capacity of the indirect heating boiler;

Attention! To compensate for the thermal expansion of water in the boiler, it is necessary to take a tank designed for water supply.

How to install a membrane tank

Not only the performance of a particular system, but also the service life of the tank depends on how correctly the membrane-type expansion tank is installed and connected. The first thing to do is to put and fix the tank to the wall or floor in the position required by its instruction manual. If there is nothing about this in it, then we will clarify this issue below in the text.

The second point is that a shut-off valve must be installed on the supply pipe. By closing it, you can always remove the membrane pressure tank for repair or replacement. And in order not to flood the floors of the furnace room, a drain fitting and another tap should be provided between the shut-off valve and the tank. Then it will be possible to empty the tank before removal.

Tanks for heating systems

In a situation where the documentation for the tank does not prescribe how to correctly orient it in space, we advise you to always place the tank with the inlet pipe down. This will allow for some time to extend his work in the heating system in the event that a crack appears in the diaphragm. Then the air at the top will not rush to penetrate the coolant. But when the tank is turned upside down, the lighter gas will quickly flow through the crack and enter the system.

It does not matter where to connect the cistern supply - to the supply or return, especially if the heat source is a gas or diesel boiler. For solid fuel heaters, the installation of a compensating vessel on the supply is undesirable; it is better to connect it to the return. Well, at the end, adjustment is required, for which the device of the expansion membrane tank provides a special spool on top.

The fully assembled system must be filled with water and vented. Then measure the pressure near the boiler and compare it with the pressure in the air chamber of the tank. In the latter, it should be 0.2 bar less than in the network. If this is not the case, it must be ensured by lowering or pumping air into the membrane water tank through the spool.

Tanks for water supply systems

Unlike expansion tanks for heating, accumulators can be oriented in space as you like, this of great importance does not have. It will also be useful to install fittings on the connection to the tank to cut it off from the network and empty it.

But the setting for cold and hot water supply is different. The fact is that the pressure in the pipelines creates a pump that has an upper and lower shutdown threshold. They need to be guided. It is necessary to set the pressure in the membrane tank operating in the cold water supply circuit by 0.2 Bar less than the lower pump shutdown threshold. This will avoid water hammer in the system.

As for DHW, here the air pressure in the tank should be 0.2 bar more than the upper shutdown threshold pumping station. This is necessary so that water does not stagnate in the container. More useful information you can find out by watching the video:

Conclusion

It would seem that such a simple knot as a water tank, but requires so much scrupulousness in detail. In fact, a serious approach is needed when installing any element of the home network, otherwise equally minor troubles will befall you very soon.

Pumps are units that find the most wide application in various industries, as well as in solving some problems in everyday life. There are a large number of varieties of this type appliances. Diaphragm pumps are among the most popular and practical in use. Their popularity in Russia is growing. What are their design features? What are the advantages of such pumps? What should be taken into account during their operation?

How the pump works

How does a diaphragm pump work? The scheme is this. This device consists of two cavities placed one opposite the other. They are separated by a membrane - a very flexible, but at the same time strong plate. One cavity is filled with air, the other with liquid. Between them, in turn, is a distributor that acts on the membrane so that it moves back and forth with a small amplitude.

As a result, a certain volume of fluid is displaced from one cavity, and absorbed into the other. When the membrane occupies the opposite position, the substance moves into horizontal plane- due to the presence of special valves in the design of the unit. The diaphragm pump thus operates on the principle of substance displacement - as, indeed, piston-type devices. But in the latter, as a rule, there are no flexible parts like a membrane. The manufacturing scheme of the unit guarantees high stability of the device.

Due to the design features, the diaphragm pump chamber is practically not contaminated. In this regard, this kind of devices in the course of practical operation behave more reliably than traditional piston ones. The best way Diaphragm pumps cope with pumping water, liquids with increased density and viscosity, as well as suspensions.

Construction materials

The pump diaphragm is usually made of rubber or flexible and extra strong steel grades. In turn, the body of the device is usually made of materials that are resistant to corrosion and chemical substances(if the appropriate specifics of their involvement are assumed). The supplied liquids or suspensions are directed to penstock, which is most often also made of rubber or PVC.

Benefits of Diaphragm Pumps

The diaphragm pump has a number of advantages. First, it is the exceptional ease of execution (in most technological implementations). As a rule, in units of this type there are no rotating parts and engines. Those mechanisms that set the pumps in motion are not technologically sophisticated devices. As a rule, modern diaphragm pumps are electrically driven with a fairly simple design, with a pneumatic system, or even manual operation. Secondly, these units operate with a minimum probability of failure - in fact, this property of them is due precisely to the simplicity of the design. The diaphragm pump is a device that will last a long time. Thirdly, these devices are very easy to install and assemble, not demanding on storage and transportation conditions. Temperature, air humidity and other factors environment practically do not affect the functionality of the pumps.

Technological versions

The units in question are different. Among the most common is the pneumatic pump. A membrane unit of this type operates without the participation of an electric drive, other complex transmission devices and equipment elements. Such a device is especially convenient in terms of transportation. Other noteworthy properties include the absence of noticeable heating, as well as tightness, which in some cases allows the device to be used under water. As we noted above, there are electrically driven diaphragm pumps. They are also quite common due to their versatility (they are adapted to most electrical systems used in Russia), high performance, moderate prices. There are also hydraulically driven pumps.

Thus, the main criterion for classifying devices is the type of motor. In general, the principle of operation of each type of device is the same: the membrane (or, as it is also called, the diaphragm) bends under the influence of a mechanical motor, air (if we are talking about a pneumatic drive) or water (when using hydraulic system), as a result of which the movement of the supplied substance is ensured. Some pump designs have two diaphragms. Compressed air acts on one, as a result of which it bends, advancing the supplied substance to the outlet valve. At the same time, in the area where the second membrane is located, a vacuum is formed, into which, due to natural physical laws, the substance is absorbed. And so with every movement of the drive. Two membranes in this case are connected by a mechanical shaft. Also involved in the transfer of substances air valves operating automatically. Thus, two processes take place in the pump - suction (when the first membrane rarefies the air when moving from the walls) and injection (when the second diaphragm transfers the pressure of the pneumatic flow to the liquid that has managed to get into the housing, thereby ensuring the movement of the substance to the outlet). Pressure indicators in the area rear wall the membrane that releases the liquid, and the one located at the inlet area, are thus equal. Often the unit in question has a different name - " Vacuum pump". The membrane mechanism is present in all technological implementations of the device. The reason for this is its simplicity and, at the same time, high efficiency. As for double-diaphragm pumps, they are usually pneumatic.

Pump efficiency criteria

Based on what criteria are diaphragm pumps evaluated in terms of efficiency and quality of work? Experts identify the following set of parameters.

Firstly, a pneumatic diaphragm pump (or one that is equipped with an electric drive) must operate smoothly without the need for repairs, additional adjustments, lubrication and other procedures that require production resources.

Secondly, units of this type must be environmentally friendly. In principle, this criterion is met in relation to most modern models of diaphragm pumps. Not many devices operate, for example, on gasoline or gas.

Thirdly, it is desirable that there be a workable and easy-to-use system for regulating the speed and volume of substances supplied. That is, the pump should not work only in the "on" and "off" mode. It is necessary to be able to adjust the suction intensity to the type of substance and the task being solved in production.

Fourthly, the design of the pumps must be such that if solid objects get inside the cavities, this does not lead to mechanical damage device and damage.

Also, some technical experts consider it important that the pumps have a power surge protection system (if we are talking about electric units), as well as efficiency - regarding the same type of devices.

Scope of application

There are several classes of devices in question. There is a dosing diaphragm pump, manual, vacuum - and all of them are successfully used in a variety of industries. As a rule, this is an industry - oil and gas, food, paint and varnish. chemical, as well as construction. Gradually, devices are being mastered by private individuals - in farms, For example. Miniature devices are becoming quite popular. In particular, some of them can consume very little electricity (despite this, the user will have a full-fledged membrane pump in their hands) - 12 volts. Such devices are often used by summer residents to design irrigation systems or a small water supply system. Reviews of many owners of household plots characterize small household diaphragm pumps exclusively from the positive side.

Pumping these mechanisms, especially those adapted for use in industry, can be carried out by the most different substances- water, liquids with more high density and viscosity, as well as those that allow solid inclusions (depending on the modification of the device, their allowable size varies from millimeters to several centimeters). Some models are adapted for pumping chemically aggressive substances.

Dosing pumps

There is a subtype of the units we are considering - dosing pumps. Membrane mechanisms in them, in principle, are the same as in conventional devices of this type, but the range of their purpose, as a rule, is narrower. Many device models are adapted to work just the same with chemically active substances- when there is a need for their periodic dosage.

What are their design features? Diaphragm metering pumps are usually precision pumps with exceptionally tight housings. Their productivity (intensity of pumping of substances) is very flexibly regulated. At the same time, in modern models there are options with setting the necessary parameters - as in the mode current work unit, as well as during presetting. Depending on the design and technological type of the device, this can be done manually or using drive elements.

Among the notable features of the metering pumps is the particular ease of maintenance. In particular, they are designed, as a rule, in the form of blocks - this causes simplicity and minimal labor costs when assembling or installing devices. Such pumps are usually equipped with valves adapted to the hazardous media. This is especially important, since these elements are quite sensitive.

Dosing type devices have enough large quantity moves (movements) - about 100-150 per minute. In this case, you can adjust the amplitude - in modern models this can be done using the interval 0-100%.

In some cases, the specifics of production involves the use of a "hybrid" model of devices. Namely: a diaphragm-piston pump may be required. It combines the advantages of diaphragm, as well as "classic". Consider the specifics of units of this type.

Features of piston diaphragm pumps

As such, a vacuum pump (membrane), due to the design features, is not always designed to process substances with a high density. In addition, according to some technical experts, its efficiency is not always optimal. Therefore, it is advisable to use a pump that has the characteristics of both a diaphragm and a piston. This type of device in many cases work with more high efficiency and reduced energy costs.

In addition, the scope of piston diaphragm pumps, as a rule, is wider than that of diaphragm pumps. In particular, they can be used not only for pumping liquids, but also for moving sludges, in filter presses, as part of the design of spray dryers. Some hydraulic type piston diaphragm pumps can also be used in the mining industry, in thermal power plants, in the ceramic industry, in metallurgy. Thus, devices of this type, having the advantages inherent in both membrane and piston versions, are more versatile in many modifications. That is, if diaphragm devices are more adapted for pumping liquids (with a certain percentage of solids), then "hybrid" ones can quite cope with the movement of substances, in which, in turn, the concentration of insoluble elements can be higher.

At the same time, this type of units, as a rule, is much more expensive than piston or diaphragm units separately. However, with proper optimization production process costs can pay for themselves. In addition, energy costs, due to the more efficient efficiency of "hybrid" pumps, are lower - at least in this part of the business costs will be reduced. Also, due to design features piston diaphragm pumps, the wear of parts on them is often lower than when using diaphragm devices.

How to choose a pump?

Based on what criteria should a diaphragm pump be selected (if it is a device that is not of a hybrid type)? The key parameters that can indicate the performance of devices of this type are as follows:

Pressure at the outlet valve (in most cases, the minimum should be 60 bar - but it all depends on the intended area of ​​\u200b\u200buse of the pump);

Suction height (preferably at least 4-5 meters);

The intensity of the substance supply (measured in cubic meters per hour - the range of recommended parameters is very different - from 0.5 to tens of units, it all depends on the purpose of the device);

Head transfer distance (the length of the pipe through which the substance is supplied is at least 50 meters);

Pressure compressed air(as a rule, in the range of 0.2-0.6 MPa, but there may be other values);

Permissible temperature range of pumped substances (usually 0-80 degrees);

The diameter of the holes at the inlet and outlet, as well as where the air is supplied (indicated in centimeters or inches - usually for imported models);

The limiting diameter of solid inclusions (may vary from a few millimeters to centimeters).

At the same time, the classification of pumps and the range of their purpose are so extensive that the selection optimal parameters when choosing this kind of device will always depend on the specific scope of their application.

disadvantages

The advantages of the considered device abound. This is versatility - a diaphragm pump can be used for water and a large number other liquids with different physical properties. This is environmental friendliness - as a rule, drives without emissions and gases are used in the design of devices. It's latitude technical execution- there is an electric, hydraulic, pneumatic, manual diaphragm pump. But it should also be said about the shortcomings that are characteristic of units of this type.

First, the diaphragm or diaphragm of the pump is constantly in motion. This eventually leads to wear and tear - they become less airtight, or even completely fail. But, as a rule, modern manufacturers technicians attach several spare membranes to the supplied kit, and if they run out, you can always order new ones. For example, the NVM company, supplying its flagship product - a vacuum diaphragm pump (NVM specializes in such devices), supplements the kits with spare parts.

Secondly, due to the intensity of operation, the valves of the devices also wear out. Also, in some cases, they may be clogged. solids that are present in the supplied liquids. However, they can also be replaced.

Some difficulties in the operation of pumps may be due to the periodic appearance of vapor locks at the time of suction of the liquid (if substances are processed that are characterized by high pressure vapors - for example, methyl chloride).

At the same time, the noted three shortcomings are compensated by the high maintainability of the pump, as well as the ease of replacing worn parts. In addition, in order to minimize the likelihood of damage to membranes and valves, various types of damping devices can be used simultaneously with the units (and in some cases, as part of their design), designed to smooth out impulses resulting from the movement of diaphragms. Anyway, diaphragm pumps are preferable to use than their traditional counterparts. The economic profitability of many industries is often predetermined by the ability to use just such units.