Valve regulating steam after itself. Pressure regulator valves

Calculation of the downstream pressure regulator involves determining the regulator’s capacity, the required setting range, and checking for noise and cavitation.

Bandwidth calculation

The dependence of pressure loss on flow through the pressure regulator is called throughput - Kvs.

Kvs- throughput numerically equal to the flow rate in m³/h through the fully open valve of the pressure regulator, at which the pressure loss across it is equal to 1 bar.

Kv – the same, when the regulator gate is partially opened.

Knowing that when the flow rate changes by “n” times, the pressure loss on the regulator changes by “n” times squared, it is not difficult to determine the required Kv of the pressure regulator by substituting the calculated flow rate and excess pressure into the equation.

Some manufacturers recommend choosing a pressure regulator with the closest great value Kvs from the obtained Kv value. This selection approach makes it possible to more accurately regulate flow rates below those specified in the calculation, but does not make it possible to increase flow rates above a given value, which quite often has to be exceeded. We do not criticize the method described above, but we recommend selecting pressure regulators “after itself” in such a way that the required throughput value is in the range from 50 to 70% of the rod stroke. A pressure regulator designed in this way can, with sufficient accuracy, both reduce the flow rate relative to the set one and slightly increase it.

The above calculation algorithm displays a list of downstream pressure regulators for which the required Kv value falls within the rod stroke range from 40 to 70%.

The selection results show the percentage of opening of the pressure regulator valve at which a given excess pressure at a given flow rate is throttled.

Selecting the setting range

The adjustment range of the pressure regulator depends on the compression force of the spring. Some pressure regulators are equipped with one spring as standard and have only one pressure adjustment range, while some can be equipped with springs of different stiffness and have several adjustment ranges. The pressure that the pressure regulator will maintain “after itself” should be approximately in the middle third of the regulation range.

The above algorithm for selecting a pressure regulator displays a list of regulators whose specified pressure falls within the range from 20 to 80% of the range of supported pressures.

When choosing the adjustment range, it must be taken into account that the permissible error in spring calibration at the boundary values ​​of the adjustment range is 10%.

Calculation of the regulator for the occurrence of cavitation

Cavitation is the formation of steam bubbles in a water flow, which manifests itself when the pressure in it decreases below the saturation pressure of water vapor. The Bernoulli equation describes the effect of increasing flow velocity and decreasing pressure in it, which occurs when the flow area is narrowed. The flow area between the valve and the pressure regulator seat is the very narrowing in which the pressure can drop to saturation pressure, and the place where cavitation is most likely to form. Steam bubbles are unstable, they appear abruptly and also collapse abruptly, this leads to metal particles being eaten away from the regulator valve, which will inevitably cause its premature wear. In addition to wear, cavitation leads to increased noise during operation of the regulator.

The main factors influencing the occurrence of cavitation:

  • Water temperature - the higher it is, the greater the likelihood of cavitation occurring.

  • Water pressure is in front of the pressure regulator, the higher it is, the less likely it is for cavitation to occur.

  • Throttled pressure - the higher it is, the higher the likelihood of cavitation.

  • The cavitation characteristic of the regulator is determined by the characteristics of the throttling element of the regulator. The cavitation coefficient is different for various types pressure regulators and must be indicated in their technical specifications, but in a way that most manufacturers do not indicate this value, the calculation algorithm includes the range of the most probable cavitation coefficients.

A cavitation test may produce the following result:

  • “No” - there will definitely be no cavitation.
  • “Possible” – cavitation may occur on valves of some designs; it is recommended to change one of the influence factors described above.
  • “Yes” – there will definitely be cavitation; change one of the factors influencing the occurrence of cavitation.

Calculation of the regulator for the occurrence of noise

High flow rates in the pressure regulator inlet can cause high noise levels. For most rooms in which pressure regulators are installed, the permissible noise level is 35-40 dB(A), which corresponds to a speed in the valve inlet pipe of approximately 3 m/s. Therefore, when selecting a pressure regulator, it is recommended not to exceed the specified speed.

The RAF60 valve is pressure reducing valve pilot action of the membrane type, regulating the pressure “after itself”. The RAF60 (way through) / RAF60A (angular) pressure regulator is controlled by a pilot valve, which controls the outlet pressure and regulates the opening and closing of the membrane, thereby maintaining the set pressure after the regulator. The RAF-60 pressure regulator is designed for maximum pressure 16bar. If pressure exceeding 16 bar is required, it is necessary to order a valve model G-60 (see the corresponding section)

When the pressure in the pilot line increases 1 When the outlet pressure is lower than required, the regulator automatically opens, otherwise the regulator automatically closes. When excess pressure enters the control chamber located above the diaphragm, the regulator closes. Otherwise, the regulator will open due to the pressure acting under the diaphragm.

The RAF60 pressure regulator maintains the set pressure if there is fluid flow through the valve. In case of deadlock operation, the valve will set the set pressure plus one bar.

Regulators are supplied with pilot valves having different pressure control ranges:

0.54 - 4 bar; 0.5 - 6 bar; 2 -10 bar; 2-16 bar - standard version (stock in stock).

Materials: Body and cover - ductile iron with Rilsan (Nilon11), epoxy

or enamel - special order.

Bolts and nuts: galvanized steel.

Diaphragm: natural rubber.

Before installing the valve flush the pipeline, to clean it of deposits, dirt and other things that could affect the operation of the valve.

Install according to the arrow on the valve cover indicating the direction of flow.

Check for leaks and re-tighten bolts and fittings if necessary.

1. Frame

2. Lid

3. Membrane

4. Trim filter

5. Stopcock

6. Stopcock

7. Control valve

8. Stopcock

9. Control Pilot

10. Adjustment screw

Adjustment procedure:

1. Make sure there is inlet pressure.

2. Close the shut-off valves №6 And №8 . Open the shut-off valve №5 and supply water to the valve.

3. Close the control valve № 7 all the way and then open it again 1-2 turns. Control valve № 7 adjusts valve response speed. The more the control valve is open № 7 , the faster this reaction. When adjusting the control valve, please remember that too fast a response may result in water hammer.

4. Loosen the lock nut and turn the adjusting screw №10 counterclockwise so that there is almost no pressure in the pilot spring.

5. Open the shut-off valve № 6.

6. Turn the adjusting screw № 10 clockwise until the valve begins to open.

7. To increase inlet pressure, keep turning the adjusting screw № 10 clockwise (1) turn at a time, taking short breaks between turns to allow the valve to adjust. Check the inlet pressure until it is reached required pressure. Tighten the adjusting screw lock nut № 10.

8. To reduce inlet pressure, turn the adjusting screw № 10 counterclockwise (1) turn at a time, taking short breaks between turns to allow the valve to adjust. Check the inlet pressure until the desired pressure is achieved.

To fully open the valve, close the shut-off valves № 5 And № 6 and open the stopcock № 8 . Please keep in mind that if in such a case the inlet pressure will be the same as the outlet pressure.

To close the valve, close the shut-off valves № 6 And № 8 , and open the shut-off valve № 5 .

To maintain the set pressure, open the shut-off valves No. 5 and No. 6 and close the stopcock № 8.

Price equipment is specified in price list, which can be obtained by sending a request to our email or by contacting the managers of our company.

Attention!

When ordering model RAF-60 pressure regulators, be sure to indicate the inlet pressure and the adjustment range within which it is necessary to maintain the specified pressure after the valve.


Main areas of application: steam, CO2, water, compressed air - on most non-flammable and non-aggressive liquid and gaseous media.

Why are pressure regulators needed - bypass valves and pressure reducing valves to regulate the pressure after themselves?
The enterprise has a lot of heat energy consumers, some require a pressure of 2 bar, others 4, others 8, but steam always has to be produced with maximum parameters, and only then the pressure reduced to the required value. Pressure regulators are not only pressure reducing valves, but also bypass valves, however, bypass valves are not so often used in steam and condensate systems.

The pressure reducing valve is

pressure regulator After myself, the main purpose is to reduce the pressure behind itself and maintain it at a certain level (in the area after itself), regardless of pressure surges up to the regulator (at its inlet). Pressure surges are caused by changes in steam consumption; the pressure regulator maintains a constant pressure level.

The bypass valve is The pressure regulator BEFORE itself is used much less frequently than the pressure reducing valve; it is practically not used for steam. Bypass valves are most often used to bypass pumps. When the pump supplies too much pressure, the bypass valve releases this excess pressure back to the suction (bypasses the pressure), this system allows you to save the pump.

3 main types of steam pressure reducing valves

from simpler to more complex

bellows type(eg ADCA PRV25)

It has a flexible metal bellows inside with a relatively small area, as a result of which the bellows pressure reducing valve is considered the least sensitive and is suitable for more coarse pressure adjustment after itself. If the flow of steam passing through the valve does not change significantly during operation, a bellows-type pressure reducing valve will cope quite well. Due to low accuracy and sensitivity, this valve is manufactured only in small sizes DN 15-20-25. One of the disadvantages of this valve is its relatively small throughput. Basic plus - simple design.

Pressure regulator after itself membrane(eg ADCA RP45)

There is a rubber membrane inside the metal plate, the membrane area is much larger than on a bellows pressure reducing valve, hence higher sensitivity and relatively greater accuracy in maintaining pressure after itself. A very common type of pressure reducing valve, it is capable of operating in systems with high dynamics of changes in steam flow; in comparison with a bellows valve, a diaphragm valve has a higher throughput - this is also a significant plus. An extremely durable type of pressure reducing valve, if the filter in front of the pressure reducing valve is installed correctly, even a rubber membrane in it can work for more than 10 years.

Pressure regulator after itself pilot(eg ADCA PRV47)

The main advantage of the pilot pressure regulator after yourself - the highest sensitivity and accuracy of adjustment.

The most advanced design, the most accurate pressure regulator, but at the same time the most “gentle”. This valve is equipped with a piston drive; the design has many small grooves; as a result, the valve is very sensitive to the quality of steam. Under no circumstances should such a pressure reducing valve be installed in a system with high level mechanical impurities in the steam, it is recommended to use it with pipelines made of of stainless steel or install a fine steam filter (fabric), this is the only way to ensure long work such a valve

Selection of pressure regulator

The pressure regulator after itself is always installed with a smaller size than the main pipeline! A common misconception is that the pressure reducing valve is installed to size.

A pressure reducing valve that matches the pipe size always turns out to be more powerful than required technological process, because of this the valve does not work accurately, imagine a valve operating at 10-30% of its normal power, in fact this is not much different from the “open-close” control and the main functionality of such a valve remains unused.
Basic parameters for selecting a pressure regulator after yourself:

  • Environment type.
  • Inlet pressure.
  • Outlet pressure.
  • Medium flow (min. max).
  • Ambient temperature.
  • Connection type.

THE VALVE DIAMETER WILL BE DETERMINED BASED ON STEAM PARAMETERS, PRESSURE, FLOW AND MEDIUM AND NOT FROM THE PIPE DIAMETER.

Selection by pipe - absolutely not. When selecting a pressure reducing valve, it is always necessary to narrow the pipe in front of the valve and widen the pipeline BEHIND the valve.

What does the reduction unit of a steam system ideally look like?

Normal selection of a reduction unit is carried out based on the system parameters.

Let us briefly describe the principle of selecting a pressure reducing valve assembly.

Suppose the main pipeline in front of the pressure reducing valve is - f 40, in this case the pressure reducing valve itself will be a little smaller, approximately DN 32.
BEHIND the valve it is usually necessary to expand the pipeline, usually radically.
That is, BEFORE the pressure reducing valve, the diameter of the steam pipe was f 40, and BEHIND the pressure reducing valve the pipe will need to be expanded to f 50 or even f 65. (rude)
Why is it necessary to expand the pipeline BEHIND the pressure reducing valve?
We lowered the pressure - the steam expanded - it is necessary to expand the pipeline to ensure normal passage of steam through the system.
Tell us your parameters steam system and we will make a full calculation required pressure with optimal performance characteristics.

List of equipment for correct operation reduction unit:

Condensate drainage unit in front of the pressure reducing valve - Mandatory
Shut-off valves in front of the pressure reducing valve - Mandatory
Filter in front of pressure reducing valve - Mandatory
Safety valve - Mandatory
Steam separator - ideal.

Pumping liquids is a rather complex, dynamic process. Over time due to exposure external factors The direction of movement, flow speed, and pressure in the pipeline may change. Also very strong is the influence of local resistances that arise at the places where the fittings are installed, when the pipeline is turned, and when the flow area changes.

For stable and safe work connected equipment requires stabilization of the network pressure. This requires installation additional equipment regulating water pressure in the network.

Model range of control valves

Dorot produces a range of valves that control flow conditions in water supply networks for various purposes. The operating principle of the water pressure regulator served as the basis for the classification of the model range:

  • pressure reduction valve PS - carries out regulation at the inlet section of the pipeline (upstream of itself);
  • pressure maintenance valve PR - regulation of outlet pressure (after itself);
  • differential valve DI - maintains a constant difference in pressure values ​​at the inlet and outlet.
  • Standing apart is the QR control valve, designed to relieve emergency excess pressure. This model performs the function of a fuse and is mounted not in the main pipeline itself, but on a separate branch.

How pressure is regulated

The operating principle of the water pressure regulator is based on the transfer of pressure from the pipeline to the control chamber of the valve. Depending on whether this pressure exceeds or falls below the set threshold value, the shut-off membrane reduces or increases the flow area. The required pressure value, which will determine the operation of the valve, is set on the pilot regulator.

Several modes of valve operation can be distinguished

Maintaining constant pressure up to itself - the valve closes completely when the inlet pressure decreases below a threshold value. As the pressure increases, the valve will open, increasing the flow area, thereby reducing the pressure in the system;

The operating principle of the water pressure regulator is the opposite. When the pressure decreases below the set value, the valve will be in the fully open position. As the inlet pressure increases, the valve will begin to close automatically, keeping the pressure at the outlet section of the network constant;

Maintaining a constant pressure difference at the inlet and outlet is achieved by changing the flow area. When the inlet pressure increases, the valve closes; when it decreases, on the contrary, it begins to open.

Design

In general, approximately, the valve design consists of the following elements:

  • frame;
  • regulating chamber;
  • locking element;
  • regulating pilot element.

By design, Dorot control valves are available in series 100, 300, 500. The main difference is how the water pressure regulator works. Those. Depending on the type of series, the design and orientation of the working locking element vary:

  • series 100 - spring-loaded membrane moving in a vertical plane;
  • series 300 - spring-loaded rod with vertical movement;
  • series 500 - inclined moving rod.

Pressure regulator housings can be made of cast iron or bronze. Depending on the type of connection to the pipeline, a flange, threaded or quick-release connection on clamps (viktaulik) can be implemented.

Advantages of fittings

Dorot pressure control valves are different

  • simplicity and reliability of design;
  • use of high-strength corrosion-resistant materials;
  • ease and simplicity of installation and maintenance;
  • long period of operation.

The service life and compliance with the rules of its operation depend not only on its correct installation, but also on the quality of water pressure in the pipes. Sudden surges, pressure changes and water hammer often cause breakdowns of expensive equipment. For the same reason, leaks occur, leading to significant financial costs. You can protect yourself from such troubles if you install a pressure regulator after yourself on the water supply system.

Water pressure valve: installation method

The main purpose of a water pressure valve is to provide stable pressure water inside utilities, regardless of their type. Depending on the installation location, a pressure regulator is distinguished between “after itself” and “before itself”. The first regulates the water pressure as it exits through the device, and the second regulates the pressure at the inlet.

Water valve: design features

Water control valves can be: flow-through, membrane, piston, automatic and electronic. Most simple design have flow valves. Piston engines are not as reliable due to the likelihood of corrosion associated with impurities contained in the water.
When using a membrane regulator, you can be sure of its durable and correct operation. The design of such a regulator is based on the presence of two chambers and a diaphragm between them. This regulator is cleaned much less frequently than other types.

What issue do water control valves solve?

are used to solve the following issues when organizing a water supply system:

  • By stabilizing the pressure inside the water main, compliance with the requirements regarding optimal permissible parameters is ensured.
  • The likelihood of water hammer occurring in the system, leading to leaks and equipment failure, is reduced to zero.
  • By stabilizing the water pressure, the devices, the correct operation of which is directly related to the liquid pressure at the inlet, operate normally.
  • By installing a water pressure control valve, its economical consumption is ensured.
  • When a leak occurs, the valve closes automatically and water does not flow into the room so quickly.
  • The uncomfortable noise that accompanies the opening of a tap disappears. high blood pressure and increased water pressure.

How does a membrane pressure regulator work “after itself”

Consists of the following elements:

  • Valve inlet and outlet.
  • A pipe leading to a chamber with a membrane.
  • Chambers with membrane.
  • Springs.
  • Locking disc.

The principle of operation of such a regulator is that when the water pressure increases and the chamber with the membrane is filled, a rod is activated, which is connected to the locking disk. The membrane presses on it, and the disk blocks the flow of water (fully or partially).
When the pressure inside the chamber stabilizes, the locking disc opens the hole. The regulator also operates when the pressure in the system decreases. In this case, the liquid returns to the valve through the pipe from the membrane chamber. By reducing the pressure in the chamber, the locking disk opens and the water pressure increases, increasing its pressure to the optimal value.
The main advantage of such a device is its reliability and ease of operation.

Features and advantages of Bermad brand valves

The regulator has the following advantages:

  • When manufacturing the device, current international standards are taken into account.
  • The device is manufactured based on a unique patented technology.
  • Modern, technologically advanced materials made of metal and composites are used to manufacture the device.
  • The device is universal and operates in the same mode regardless of the quality and composition of the liquid passed through.
  • The company has developed specialized and multi-purpose devices that are used depending on the purpose and operating conditions.