How does a membrane work? What is membrane clothing

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

How the pump works

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

As a result, a certain volume of liquid is displaced from one cavity and absorbed into the other. When the membrane occupies the opposite position, the substance moves in a horizontal plane due to the presence of special valves in the design of the unit. The diaphragm pump thus operates on the principle of displacing a substance - just like piston-type devices. But the latter, as a rule, does not have flexible parts like a membrane. The manufacturing scheme of the unit guarantees high stability of the device.

Due to the design features, the chamber of the diaphragm pump is practically not contaminated. In this regard, during practical operation, this type of device behaves 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.

Materials of construction

The pump diaphragm is usually made of rubber or flexible and especially durable steel. In turn, the device body is usually made of materials that are resistant to corrosion and chemicals (if the corresponding specifics of their use are assumed). The supplied liquids or suspensions are directed into a pressure pipeline, which is most often also made of rubber or PVC.

Advantages of diaphragm pumps

A diaphragm pump has a number of advantages. Firstly, it is exceptionally simple to implement (in most technological implementations). As a rule, units of this type do not have rotating parts or motors. The mechanisms that drive the pumps are not technologically complex devices. As a rule, modern diaphragm pumps are electrically driven and have a fairly simple design, with a pneumatic system, or even manual operation. Secondly, these units operate with a minimal probability of failure - in fact, this property is due precisely to the simplicity of the design. A diaphragm pump is a device that will last a long time. Thirdly, these devices are very easy to install and install, and do not require storage and transportation conditions. Temperature, air humidity and other factors environment have virtually no effect on the functionality of the pumps.

Technological versions

The units in question are different. Among the most common - a membrane unit of this type operates without an electric drive, other complex transmission devices and equipment elements. This device is especially convenient from a transportation point of view. Other notable properties include the absence of noticeable heating, as well as the 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, and reasonable price. There are also hydraulically driven pumps.

Thus, the main criterion for classifying devices is the type of motor. In general, the operating principle 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 engine, air (if we are talking about a pneumatic drive) or water (when using a hydraulic system), resulting in the movement of the supplied substances. Some pump designs have two diaphragms. One is affected and as a result it bends, moving 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. In this case, the two membranes are connected by a mechanical shaft. Also involved in the pumping of substances air valves, acting automatically. Thus, two processes occur in the pump - suction (when the first membrane rarefies the air when moving from the walls) and discharge (when the second diaphragm transfers the pressure of the pneumatic flow to the liquid that has managed to get into the body, thereby ensuring the movement of the substance to the outlet). The pressure indicators in the area of the rear wall of the membrane that releases the liquid and the one located at the entrance site 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 equipped with an electric drive) must operate smoothly without the need for repairs, additional settings, lubrication and other procedures that require production resources.

Secondly, units of this type must be environmentally friendly. In principle, this criterion is met for 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 supplied substances. That is, the pump should not operate only in the “on” and “off” modes. It is necessary to be able to adjust the intensity of absorption 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 will not lead to mechanical damage to the device and its breakdown.

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

Scope of application

There are several classes of devices in question. There is a dosing diaphragm pump, a manual pump, a vacuum pump - and all of them are successfully used in a variety of industries. As a rule, this industry is oil and gas, food, paint and varnish. chemical, as well as construction. Gradually, the devices are being adopted by private individuals - on 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 his hands) - 12 Volts. Devices of this kind are often used by summer residents to construct irrigation systems or small water pipes. Reviews from many owners personal plots characterize small household diaphragm pumps exclusively on the positive side.

These mechanisms, especially those adapted for use in industry, can pump a variety of substances - water, liquids with a higher density and viscosity, as well as those that allow solid inclusions (depending on the modification of the device, their permissible size varies from millimeters up 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. The membrane mechanisms in them are, in principle, the same as in conventional devices of this type, however, the range of their purpose is, as a rule, narrower. Many device models are adapted to work specifically with chemically active substances - when there is a need for their periodic dosage.

What are the features of their design? Diaphragm metering pumps, as a rule, are precision, with exceptional tightness housings. Their performance (intensity of pumping substances) is very flexibly regulated. At the same time, in modern models There are options for setting the required parameters - both in the current operating mode of the unit, and during the preliminary setup process. Depending on the design and technological type of the device, this can be done manually or using drive elements.

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

Dosing type devices have a fairly large number of strokes (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 require the use of a “hybrid” model of devices. Namely: it may be required. It combines the advantages of diaphragm, as well as “classic”. Let's consider the specifics of units of this type.

Features of diaphragm piston pumps

As such, (membrane), due to its design, is not always designed for processing substances with 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 pump. In many cases, this type of device operates with higher efficiency and lower energy consumption.

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

At the same time, units of this type are usually much more expensive than piston or diaphragm units individually. However, if the production process is properly optimized, the costs can be worth it. In addition, energy costs, thanks to the more efficient efficiency of “hybrid” pumps, are lower - at least in this part, business costs will be reduced. Also, due to design features Diaphragm-piston 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 you choose a diaphragm pump (if we are talking about a non-hybrid device)? Key parameters, which can indicate the performance of devices of this type, are the following:

Pressure at the outlet valve (in most cases the minimum value should be 60 bar - but it all depends on the intended use 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 intended purpose of the device);

Pressure transmission distance (the duration of the pipe through which the substance is supplied is at least 50 meters);

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

The maximum diameter of solid inclusions (can vary from several millimeters to centimeters).

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

Flaws

The device in question has plenty of advantages. This is versatility - a diaphragm pump can be used for water and large quantity other liquids with different physical properties. This is environmentally friendly - as a rule, drives without exhausts and gases are used in the design of devices. This is the breadth of technical execution - there is an electric, hydraulic, pneumatic, manual diaphragm pump. But it should also be said about the disadvantages that are characteristic of units of this type.

Firstly, the membrane or diaphragm of the pump is constantly in motion. Over time, this leads to their wear - they become less airtight, or even fail altogether. But, as a rule, modern equipment manufacturers include several spare membranes with 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 use, the valves of the devices also wear out. Also, in some cases, they may become clogged with solids 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 moment of liquid absorption (if substances characterized by high vapor pressure are being processed - for example, methyl chloride).

At the same time, the three disadvantages noted 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 arising from the movement of the diaphragms. One way or another, it is preferable to use diaphragm pumps than their traditional counterparts. The economic profitability of many industries is often predetermined by the ability to use just such units.

« Membrane- this is either the thinnest film that is laminated (welded or glued using a special technology) to the upper fabric, or a special impregnation that is rigidly applied to the fabric using a hot method during production. WITH inside the film or impregnation can be protected by another layer of fabric.”

From this we can conclude that important property membrane clothing - it is very light.

Non-porous membranes they work on the principle of osmosis (not space, but osmosis - remember physics and chemistry lessons at school).

The system is as follows: vapors fall on the inside of the membrane, settle on it and, through active diffusion, quickly pass to outer side membranes. (Again, only if there is driving force- difference in partial pressures of water vapor).

What are the advantages of non-porous membranes? They are extremely durable, do not require careful maintenance, and work properly in a wide temperature range. Such membranes are usually used in top-end (expensive and most functional) products.

What are the disadvantages? At first it may seem that the products are getting wet, but this is precisely the same fumes that accumulate on the inside of the product. That is, they begin to breathe more slowly, but advanced non-porous membranes, “heating up”, sometimes surpass porous membranes in their breathing properties.

Pore membranes- these are, roughly speaking, membranes that work according to the following principle: drops of water that fall on the membrane tissue from the outside cannot pass through the pores of the membrane inside, since these pores are too small. The steam molecules formed when you sweat are freely removed from the inside of the membrane tissue through the pores of the membrane (since a steam molecule is thousands of times smaller than a drop of water, it can freely penetrate through the pores of the membrane). As a result, we obtain waterproof membrane fabric on the outside of the product and breathable (steam-removing) properties from the inside of the product. At the same time, a drop of water will not be able to seep into such a hole. But how (you ask) will clothes with holes withstand the wind? After all, wind molecules are also significantly smaller than a drop of water! In this case, the membrane works differently. The wind, entering long and narrow pores, begins to swirl and does not pass through.

What is the advantage of pore membranes? They "quickly" begin to breathe, i.e., remove evaporation as soon as you begin to sweat (provided that there is a difference in the partial pressures of water vapor inside and outside the jacket. That is, when there is a driving force).

What are the disadvantages? This membrane “dies” quite quickly, that is, it loses its properties. The pores of the membrane become clogged, which greatly reduces the breathability. If washed incorrectly, the jacket may begin to leak. This drawback can manifest itself especially strongly if you are not a particular fan of taking care of your things (use special DWR sprays, detergents for membrane fabrics, etc.).

Membrane combination- everything is very cool. The system is as follows: the upper fabric is covered on the inside with a pore membrane, and on top of the pore membrane there is also a thin coating (i.e., a non-porous polyurethane membrane film). This magical fabric has all the advantages of pore and non-pore membranes without the disadvantages. But high technology comes at a high price. Very few companies use this membrane in their products...

How does a membrane “work”?

If you become the owner of membrane clothing, then you should not put it on a cotton T-shirt and go for a run in twenty-degree frost. This is how the membrane does not “work”. The idea is to keep the heat inside by wicking moisture out and preventing it from being absorbed into your clothes.
The classic scheme of protection against moisture and cold consists of three layer elements, and the membrane is only one of them, the very last.

First layer of clothing- this is thermal underwear (special thin clothing that retains the heat generated by the body). Cotton should be avoided, as it greedily absorbs moisture, and, therefore, there can be no talk of any warmth.

Second layer- woolen clothing (with an admixture of synthetic fabrics that wick away moisture) or clothing made from artificial materials such as fleece (Fleece) or Polartec. It is important that the second layer is voluminous and retains heat.

But only third, outer layer - thin membrane jacket.
If the frost is mild, then you can get by with only the first and third layers, which will provide you with mobility and mobility.

And finally, it is important to understand how moisture will be removed outside. Due to the difference between the air pressure under the membrane jacket and outside. Therefore, if you decide to sit motionless in a snowdrift, hoping for a “magic” membrane, there is a real chance of catching a serious cold. However, this does not mean at all that you need to run around like crazy waiting for a pressure difference for the membrane to “work.” It’s enough just to move more or less actively (just in case: walking is also movement).

Characteristics of membrane fabric

A membrane can be characterized not only by its structure and operating principle (with or without pores), but also by its two main parameters: water resistance and the ability to release steam.

Water resistance(or water resistance), waterproofness (millimeters of water column, mm water column, mm H2O) - the height of the water column that the membrane (fabric) can withstand without getting wet. In fact, this parameter indicates the water pressure that can be maintained without getting wet. The higher the water resistance of the membrane, the more intense precipitation it can withstand without letting water pass through it.

Vapor permeability(g/m2, g/m2) - the amount of water vapor that can pass through square meter membranes (tissues). Other terms are also used: Moisture Vapor Transfer Rate (MVTR), moisture permeability. Most often, the value g/(m2.24h) averaged over a long period of time is indicated - the amount of water vapor that a square meter of membrane (fabric) can pass through in 24 hours. The higher it is, the more comfortable the clothing.

The base level is usually 3,000mm/3000g/m2/24 hours.
Mid-range membranes typically have a rating of 8,000mm/5,000g/m2/24hrs or so.
Waterproof fabrics high class usually at least 20,000mm water column, and breathability at least 8,000g/m?/24 hours.

About gluing seams

Taped seams prevent moisture from penetrating through the seams, and, as a result, you feel dry and comfortable.
Inscription " all seams are sealed " means that all seams in this product are taped.

If the label says “critical seam sealing,” this means that only the main seams are taped in the product, which may or may not result in leaks in some places. It is worth noting that in products positioned by the brand as semi-urban, this option is very acceptable (usually these are products with insulation). Here, every buyer is free to choose what he wants and what is suitable for him personally.

Water-repellent coating - DWR

Look - the droplets on the fabric are not absorbed, but lie on the fabric, rolling into balls! This is a DWR (Durable Water Repellence) coating that does not allow water to pass even through upper layer tissue (that is, absorbed into it). On DWR coated fabric, water beads up and rolls easily. DWR, by the way, is not a durable thing, and disappears over time (washed off), and appears on the fabric. wet spots(in contact with water). This does not mean that the product gets wet, since the membrane will still not allow water to pass through, but some discomfort may be present. The resulting layer of water on top will not allow the membrane to work, no matter how cool it is. In addition, in pore membranes, in this case, water can pass through the membrane. Specially developed products with this same DWR coating (NIKWAX, WOLY, salamander), sold in stores selling extreme clothing, will help you avoid dying of DWR.

Pros and cons of membrane clothing

Pros:

it is light and comfortable: the child can move outside and enjoy a walk, rather than sitting in a stroller and only being able to move his head.
you don’t waste a lot of nerves pulling on and fastening another layer of “warmer” clothing
the child will not cry while you get dressed and go outside.
protects well from rain and snow, durable and lightweight;
again, your nerves are calm and you don’t have to run home after another fall in a puddle.
it is not blown by the wind and removes body fumes well;
it is suitable for both not very cold windy weather and frosty weather;
You need to wear less clothing underneath than usual.
Dirt is very easy to remove, you can forget about washing every other day and choose bright colors.

Minuses:

membrane clothing is quite expensive
requires special care
relatively short-lived
clothes for it must be selected in a special way;
Not suitable for lovers of everything natural.

Types of membranes

The best is the Gore-Tex microporous membrane, developed in the 60s of the 20th century for astronaut suits. For ski clothing, as a rule, two-layer Gore-Tex is used, which is lighter and softer than three-layer, from which jackets for tourism and mountaineering are mainly made.

The water resistance of the two-layer membrane is 15,000 mm, and the moisture evaporation rate is 12,000 g/m2/24 hours.

The non-porous membranes Triple-Point and Sympatex, ULTREX, and other fabrics under the general name hi-pora are kept approximately on the same level with Gore-Tex. Their water resistance ratings are slightly lower - approximately 12,000 mm, but this is quite enough to not get wet even in heavy rain or snowfall. These membranes also breathe very well. Sympatex, in addition to being used in its pure form, is part of the Omni-Tech technology, which includes a membrane, a special water-repellent coating and a windproof layer.

Ceplex and Fine-Tex membranes, which are now very actively used in the production of sportswear, are much cheaper. The main disadvantage of Ceplex is its fragility.

If clothes with Gore-Tex, Triple-Point or Sympatex last 4-5 years with careful handling, then Ceplex rarely withstands more than one or two seasons of active use and begins to get wet. Fine-Tex, on the other hand, does not get wet, but breathes a little better than polyethylene. But these membranes themselves and clothing with them cost an order of magnitude less than their counterparts from Gore-Tex, Triple-Point and Sympatex.

The Ceplex membrane is used in the production of Vaude brand clothing.
Membrane Fine-Tex, Sympatex - in brands Bolik, COOLAIR.
hi-pora membranes - in the brands Commandor (Hi-Pora™/Evapora™), Lowe Alpine (Triple Point Ceramic), Columbia (Sympatex)

Membrane, insulation, outer fabric and weather conditions, let’s sum it up at the layman level by creating review on brands, presented today in Ukraine.

On average, you can start wearing winter membrane clothing from +5+7 °C (for cool children). A membrane overall or set worn by a baby during autumn rain or during a spring thaw will save the mother’s nerves (but not those around her) and will give the child a lot of joy from interacting with water. If no active fiddling around in the puddle is expected, fabric impregnated with DWR will suffice.

It would be very nice if the seams in the product are taped. Reima tec (for cool children, but if the child is active and not freezing, it is better to get by with demi-season clothing), Huppa (jacket without fleece insulation or with 80 g of insulation, fleece-lined trousers) are suitable for such conditions. Under the overalls - a minimum of clothing, ideally - thermal underwear. Because, as practice shows, when there are a lot of puddles around, it is not difficult for a child to walk inactively.

When the thermometer shows 0...-5 °C, you can either add 1 layer, or change outer clothing. As an option - Reima tec (you can add a fleece blouse or a mixed golf shirt to your thermal underwear), Huppa (jacket without insulation on fleece or with an amount of insulation of 80, 130 g, trousers with fleece or bib overalls 100 g), Lenne (products with an amount of insulation no more than 150 g), Bambino, TCM, H&M.

Suitable for temperatures of -5...-15°C are Reima tec (it is advisable to wear thermal underwear or other underwear and a fleece overall under the overalls), Huppa (jackets with insulation amounts of 130, 160, 200 g, bib overalls 100 g, overalls 200 g), Lenne ( products with insulation 150 g, 330 g), at temperatures below -10 °C you can wear a down jacket (O'Hara, Chicco, Geox) or overalls Kiko, Donilo, Gloria Jeans, Lemmi, Shaluny, Gusti, Bambino, TCM, H&M.

15 °C and below - many mothers cancel walks at this temperature. If you are not one of those people, make sure that the child does not sit still on the street (in which case a fur coat will not help much), which means that he is not dressed in thick clothes and can move freely.

15-20 °C will not be scary if the child rides down the slide, sculpts a snow woman, plays snowballs (if you don’t believe me, try it yourself!). Suitable for Reima tec (not for everyone, depends on the child), Huppa (jackets with insulation amounts of 130, 160, 200 g, bib overalls 100 g, overalls 200 g), Lenne (products with 150 and 330 g of insulation), down jacket (O'Hara , Chicco, Geox), overalls Kiko, Donilo, Gloria Jeans, Lemmi, Shaluny, Gustі, Bambino, TCM, H&M.

These recommendations are suitable for small pedestrians. If the baby walks, but still rides in a stroller, you can, after dressing him for a walk, put him in an envelope in the stroller. Then you won’t freeze in the stroller and won’t sweat while running.

For babies in the first year of life, one-piece overalls are well suited - Huppa (200 g), Lenne (baby models or transformable overalls), down jackets (Chicco), overalls Kiko, Donilo, Gloria Jeans, Lemmi, Shaluny, Gusti, sheepskin overalls. You can also choose lighter options, but put a fur envelope in the stroller and enjoy your walk

When heated, any coolant expands and increases in size. As a result, the pressure in a closed heating system gradually increases and reaches a critical point. The membrane expansion tank of the heating system is designed to prevent the destruction of components and pipelines due to expansion of the coolant.

The main function of the expansion tank is to optimize the operating pressure in the heating system. Closed heating systems cannot operate properly unless connected to membrane tank for heating.

Diaphragm expansion tank design

Although membrane expansion tanks may differ depending on the manufacturer and purpose, some details remain unchanged in any model purchased. Namely:

Metal body - prerequisite production of tanks is the ability to withstand extreme loads without breaking the tightness.
The membrane must be highly elastic and capable of responding to changing pressure associated with heating of the coolant. At the same time, high demands are placed on the membrane in terms of strength. Typically, rubber is used in the production of membranes.

The design of a membrane heating tank for closed heating systems involves the use of tanks with replaceable and non-replaceable diaphragms. Each design has both its advantages and disadvantages.

How does a membrane expansion tank work?

The operating principle of a membrane expansion tank is based on the use of physical laws. After heating the coolant, the following occurs:

Water or antifreeze begins to expand, resulting in an increase in its volume in the system.
The design of a membrane-type expansion tank implies that it is filled with gas.
The membrane is a kind of layer between the gas and the coolant.
When heated, the liquid, expanding and creating pressure, enters the tank and displaces air or gas.
After the coolant pressure drops, the gas pushes the coolant out of the tank using a membrane.
The operation of the safety valve in a heating system with a membrane tank is to relieve excess gas pressure in the event of large expansion of the coolant. The pressure relief valve ensures safe operation of the system in case of overheating of the fluid or antifreeze.

For normal heating operation, there must be a pressure in the membrane tank corresponding to the height of the top point. If the tank is installed in two-storey house and the maximum height from the boiler on the ground floor to the radiator on the top is 7 meters, then we take 0.7 into the calculations and add 0.5 to it. We obtain the initial pressure when coolant is supplied to the system. The resulting coefficient for the tank should be lower by 0.2. It turns out that the normal pressure in the membrane-type expansion tank in this case is 1 atm.

Like all heating equipment, the membrane tank needs maintenance. It must be maintained at appropriate operating pressure and refilled with gas or air from time to time.

Types of expansion tanks for heating systems

Each manufacturer introduces innovations into the design of a closed expansion tank. But basically all modifications can be divided into several groups depending on the membrane used. Namely:

The expansion tank membrane is in the form of a diaphragm. This device is more like a barrel separated by a movable rubber partition. When the liquid enters its section, it fills the reservoir, and then, under pressure, it begins to compress the gas, gradually moving the membrane. This device is not always effective for houses with a small heated area.
Round membrane tanks balloon type. In this case, the air chamber is located around the perimeter of the entire tank. It surrounds the water chamber. As pressure increases, this chamber begins to expand like an inflated rubber ball. The uniqueness of such a device is that with its help it is possible to more accurately control the coolant pressure, even in closed systems with a small volume of liquid in the pipeline.
Non-removable membrane. The diaphragm is attached around the entire perimeter. Non-removable membranes are intended for use in private heating systems and for heating cottages. Limited use and installation in small industrial facilities is allowed.
Tank with replaceable membrane. They are a hollow pear. Removable membranes are able to work effectively in systems with high heating intensity of the coolant and high atmospheric pressure. The advantage of such a device is the ability to replace the diaphragm. The disadvantage is that high demands are placed on the work required to change the membrane. The membrane must not be distorted during installation.

The role of the expansion tank in the heating system is not limited to absorbing excess pressure. Before choosing a suitable device, it is necessary to determine for what purpose it is planned to be used.

How to calculate the volume of a membrane type expansion tank

When choosing a tank, you need to pay attention to the following several indicators:

Temperature range considered operating for the device.
Membrane elasticity.
Diffusion stability.
Dynamic indicators.

In addition to these four criteria, it is important to calculate the pressure in heating system with a membrane type tank. Pressure data will help you choose the most suitable model tank. Requirements for performing calculations in complex systems closed type are presented high. Correct calculations can be made using the following formula:

V=(V sys ×K)÷D

The volume of the expansion tank for a closed heating system is, according to this formula, the product of the volume of the system V sys and the coefficient of increase in coolant K (it is 4%) divided by the efficiency of the tank itself.

D=(Pmax-P start)÷(Pmax+1)

P - in this case is an abbreviation for maximum and initial pressure. Using these two formulas, you can easily perform calculations and select the required model.

In addition to the standard round device, you can purchase a rectangular membrane-type expansion tank; it is more convenient to use and has an attractive appearance.

How to install a membrane type expansion tank

Installing an expansion tank in a closed heating system is quite simple. The only condition for connection is an understanding of the basic principles of operation. Installation can be carried out by following the following recommendations:

It is better to install the expansion tank before rather than after circulation pump, this will help avoid surges in pressure. There are no other restrictions regarding the installation location.
After installation, it is necessary to check whether the operating pressure of the device matches that required. The check can be done quite simply if you install a pressure sensor in the tank when connecting. A sensor measuring the pressure in the tank is installed directly at the inlet. If the existing indicators do not meet the required ones, it is necessary to bleed the air and pump the device again until the diaphragm pressure meets the required one.
When the heating system is closed, the expansion tank is correctly installed so that the inlet valve (water pipe) points downwards. This will allow the coolant to drain, even if the membrane fails. Some models have a coolant level indicator, which allows you to determine whether the liquid has been completely drained from the system.

Installation of a membrane tank is a prerequisite for installing a closed-type heating circuit. Some boilers are already equipped with such a device; in this case, if necessary, installation of an additional tank is allowed.

The modern world offers a huge choice latest technologies and developments in various fields, and often these innovations can find application in completely different areas.
One such example is membrane - a material that was originally used only by manufacturers of clothing and equipment for tourists, athletes, that is, for those who deal with extreme weather conditions, heavy physical activity, and who need equipment with certain properties.
And today, membrane fabrics are widely used in light industry for sewing ordinary outerwear, including children's.

Types of membrane

What is a membrane? The membrane is a high-tech material that is highly waterproof and at the same time retains the ability to “breathe”. There are two types of membranes: hydroporous and hydrophilic.

Hydroporous membranes have many microscopic holes, called pores. The pores are many times smaller than a drop of water, so moisture cannot penetrate inside. And at the same time, water molecules in the form of steam freely exit through the membrane.

Membranes of this type are sensitive to dirt, which simply clogs the pores, and over time they can become clogged, which negatively affects their properties. But such membranes breathe better than others.

Hydrophilic membranes are fabric on which a film is thermally applied that does not allow water to pass through. At the same time, the fabric remains breathable, because thanks to the loose chemical bonds molecules of evaporating moisture are transferred, as if along a conveyor, from the inside of the film to the outside. Dirt and foreign substances on such a membrane do not affect its vapor permeability, breathability and waterproofing ability.

Caring for hydrophilic membranes is easier, but their vapor permeability is lower than that of hydroporous membranes.

How do membranes work in practice?

It is important that we, and especially our children, feel comfortable in their clothes. When we talk about comfort, we mean microclimate - thin layer air between skin and clothing. We are comfortable when the temperature of this layer is approximately 32-34 degrees and the relative humidity is 40-60%. Any deviations are noticeable.

The microclimate may be affected various factors: weather conditions, clothing properties, physical activity.

"The cold wind, penetrating through clothing, displaces the layer warm air around the skin. Clothes made from membrane fabrics are windproof, and this property allows them to stay on for a long time in sub-zero weather. outdoors and not freeze.

During physical activity, our body releases moisture, simply by sweating. If this moisture is not removed in a timely manner, it covers the skin with a film and begins to cool at rest and heat up during active movement, causing discomfort. The membrane does not allow moisture to linger inside the clothing, but removes evaporation outside, ensuring proper microcirculation and maintaining the desired humidity and temperature.

Thus, the membrane allows you to preserve the usual microclimate as much as possible, namely, a temperature of about 33 degrees and a humidity of about 50% - unchanged. Regardless of the external temperature and level of physical activity. Therefore, in both hot and cold weather, we feel comfortable in membrane clothing.

How to wear the membrane?

For normal operation of the membrane, the following rules must be observed:

Clothes under the membrane should be made of synthetic or mixed fibers (synthetic content of at least 10-20%), or wool. We remember that excess moisture must be removed from the body, and, for example, 100 percent cotton is hygroscopic, it absorbs sweat, causing hypothermia. You can leave your panties in cotton.
Layering: the first layer is underwear, the second layer is insulation, the third layer is the membrane clothing itself. Underwear, as we have already found out, should be made of synthetics or with the addition of synthetics. This could be special thermal underwear or just a turtleneck and tights. Underwear made from 100 percent wool is also allowed - for lovers of natural fabrics, fortunately, products made from delicate, non-spiking wool are now available on the market.
Insulation: at a temperature of minus 5-10 degrees, we begin to insulate ourselves, this can be a jumpsuit made of wool or fleecy fleece. Membrane clothing: set or overalls. All!
Physical activity: The membrane works in motion. If you engage in winter sports or even just actively walk, then the membrane is your choice. It is probably premature to buy membrane clothing for children who spend most of their walks sleeping in a stroller. A down jacket or clothing with other insulation is more suitable for them.

Membrane advantages

Membrane clothing has a number of advantages.

She maintains constant optimal temperature approximately 33 degrees, so there is no fear that the child will overheat or freeze. Moreover, this temperature does not depend on how many degrees in external environment- minus 20 on the street or plus 15 in the car. You can enter without fear shopping mall or a clinic, you just need to take off your hat.

Membrane clothing non-volumetric due to its properties and the use of modern insulation materials. If previously it was difficult for children in fur coats and cotton pants to move on the street, now even those who have only recently learned to walk can easily move and actively explore the world around them.

Membrane clothing light. This is true both for the children themselves and for mothers who often pick up children in their arms.

One set of clothes is enough, even if there are mud and puddles outside. Firstly, you can be sure that if your child falls into a puddle, he will remain dry thanks to the waterproof membrane. And secondly, when you come home, it’s enough to wash the soiled clothes under running water, wiping them with a sponge if necessary, and hang them up to dry. The membrane dries very quickly. In addition, manufacturers of membrane clothing, in particular Luhta, design products so that the areas most susceptible to contamination (bottoms of trousers, knees, lower back) are made of dark-colored fabric.

Membrane care

Caring for the membrane is not difficult, the main thing is to follow simple rules.

To ensure that your clothes last a long time, first of all follow the instructions included with the product when washing and drying.
Wash the membrane either by hand or in washing machine in delicate wash mode at 30 degrees. Use special means for membrane clothing or any liquid.
Heavy soiling You can first wash it under running water by rubbing it with a sponge.
Before washing in the washing machine, check the pockets, close the zippers and turn the item inside out.
The membrane is washed without pre-soaking.
Do not use rinse conditioners.
After washing, the product is hand-wrung without twisting. Let's allow spinning in a washing machine at the lowest speed.
Clothes should be dried flat and room temperature(Do not under any circumstances dry membrane clothing on the radiator!).

Why do you need a membrane tank for water supply? When organizing an autonomous water supply for a private home from wells or wells, it is necessary to create an emergency water supply. An expansion tank for water supply is perfect for these purposes. These containers are practical and have a large volume, but to ensure normal operating conditions it is necessary to use a number of devices and not limit yourself to just one installation.

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

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

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

The operating principle is as follows: when the system is turned on (started), the pump pumps water into the water chamber until it is filled. At the same time, the volume of the second chamber is significantly reduced. When the air chamber contracts, the amount of air inside it does not change, so the pressure on the membrane increases. Accordingly, the pressure in the system increases.

IN expansion tanks a membrane is used to divide it into 2 reservoirs, one with air and the other with liquid. In this case, it is necessary to have pressure monitoring 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 of the entire water supply system.