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What is double plate swing check valve

August 3, 2020

Main features of Double plate swing check valve:

double wing check valve (5)

Two valve plates are fixed on the valve body along a pivot axis, and two springs are installed on the butterfly plate above the sealing surface. Driven by the pressure of the medium flow, the spring is compressed to force the butterfly plate to open. When the medium flows back , The spring forces the valve to close. This kind of valve can be assembled on horizontal and vertical pipelines.

Design Features of Double plate check valve:
Design standard: API 594, API 6D, ASME B16.34, GB/T 12236
Good sealing performance
Small size and light weight
Wide application, flexible disc, fast closing
Valve plate closes quickly
Small closing impact

Product Range:
Body material: carbon steel, stainless steel, alloy steel
Caliber: 1/2″~60″(DN15~DN1500)
Pressure range: Class150~2500 (PN10~PN420)
Connection method: RF, RTJ, BW
Working temperature: -196℃~+560℃

TH VALVE is one of the largest double plate check valve manufacturers in China, main products are butterfly valves, check valves: butterfly valve, lug type butterfly valve, wafer type butterfly valve, U-type butterfly valve, double flange butterfly valve, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…)

What is a Single-disc swing check valve

August 3, 2020

Product details of Single-disc swing check valve:
Brand: THV

single disc swing check valve body

Type: TH-CKV-SDS
Material: Stainless steel, cast iron, etc.
Connection form: Wafer structure Butterfly type
Nominal diameter DN15-DN400 (mm)
Applicable medium: fresh water, sea water, steam, food, medicine —-
Form Butterfly Pressure Environment Normal Pressure Standard British Standard American Standard National Standard Flow Direction Two-way Drive Mode Manual Operating Temperature Normal Temperature Type (Channel Position) Straight-through

Applicable medium:
Fresh water, sea water, air, steam, food, medicine, and various oils, acids, alkalis, salts, etc.

Features of single disc swing check valve:
Long service life, reliable sealing performance and no frequent maintenance. The flow characteristic of the butterfly valve is 3 times that of the globe valve and 75% of the gate valve of the same specification. The butterfly valve can realize the switching and regulating function of the fluid in the pipeline. Compared with the gate valve and the stop valve, it has a better multifunctional type. The various choices of internal parts and elastic materials make butterfly valves widely used in the chemical industry.

The butterfly valve is light in weight and small in size. For example: the weight and volume of a 10″ butterfly valve are respectively 1/9 and 1/6 of a 10″ gate valve. Therefore, the butterfly valve is easy to install and can save the cost of the piping system. Compared with metal-sealed gate valves and globe valves, soft-sealed butterfly valves can achieve complete air tightness. The butterfly valve is easy to operate and can realize the opening and closing function within a 90° rotation range. The price of the butterfly valve of the same specification is about 35-40% of the price of the gate valve, and the installation cost of the butterfly valve is relatively low. The correctly installed butterfly valve has a certain degree of self-cleaning, and it is not easy to fail due to the stolen goods in the pipeline.

Note: The valve connecting flange size in this table conforms to BS4504 PN10, and the transmission connecting flange size conforms to ISO5211. In addition, it also meets the flange connection standards of other countries and the special connection sizes required by customers.

TH valve is one of the largest butterfly valve manufacturers in China, main products are butterfly valves, check valves.., Main products: butterfly valve, lug type butterfly valve, wafer type butterfly valve, U-type butterfly valve, double flange butterfly valve, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…)

What is a single plate check valve

August 3, 2020

Single-plate check valve is also called single-disc check valve, wafer check valve: it is a valve that can automatically

6 single-plate-swing-check-valve-2

prevent fluid backflow. The disc of the check valve is opened under the action of fluid pressure, and the fluid flows from the inlet side to the outlet side. When the pressure on the inlet side is lower than that on the outlet side, the valve flap is automatically closed under the action of the fluid pressure difference, gravity and other factors to prevent the fluid from flowing back. It can be installed horizontally or vertically. For vertical installation, pay attention to the water flow from bottom to top, and pay attention to whether the installation direction is correct.

There are two types of check valves. One is installed at the end of the vertical suction pipe in front of the water pump bai. The purpose is to fill the water pump without pumping water once, because the water pump can only be used when there is no water in the pump and the suction pipe in front of the pump. Idling cannot pump water, so the pump must be filled with water to pump out water. The installation of this pump is a method when it is above the liquid level. It is also called a negative pressure method such as pumping water up from a well. Another way to install the pump is that the liquid level is higher than the pump. This method is generally used for secondary water supply. Because the liquid level is higher than the pump, it is not necessary to close the pump outlet valve when starting and stopping the pump, so the check valve should be installed in the The rear of the water pump.
Whether the check valve is installed before or after the valve does not affect its function.

Precautions for installation of single plate check valve

1. The check valve is a one-way valve, so the installation position, height, and direction of inlet and outlet must meet the design requirements, and the direction of medium flow should be consistent with the direction of the arrow marked on the valve body.

2. Check the appearance before installing the check valve. The nameplate of the valve should comply with the current national standard “General Valve Marking” GB 12220. It can be used after all standards are qualified.

1. Do not allow the check valve in the pipeline to bear weight, especially the large check valve, which should have an independent support and not be affected by the pressure generated by the pipeline.

What is vertical check valve

July 31, 2020

Vertical check valve: Due to the pressure of the medium at the inlet end of the pipeline, the valve can be opened or

silent check valve (3)

closed by overcoming the spring resistance. When the medium pressure at the inlet end is lower than that at the outlet end, the spring pushes the valve core to the valve seat to close the valve, preventing the medium from flowing back, so it plays a role of check. Vertical check valves are widely used in chemical, liquefied petroleum gas, fluid and other industries. According to the structure of the check valve, it can be divided into three types: lift check valve, swing check valve and butterfly check valve.

Introduction of vertical check valve:
Vertical check valve refers to the valve that automatically opens and closes the disc depending on the flow of the medium itself to prevent the medium from flowing back. It is also called check valve, one-way valve, reverse flow valve, and back pressure valve. Check valve is a kind of automatic valve, its main function is to prevent the back flow of the medium, prevent the pump and drive motor from reversing, and discharge the container medium. Check valves can also be used to supply pipelines for auxiliary systems whose pressure may rise above the system pressure. Check valves can be divided into swing check valves (rotating according to the center of gravity) and lift check valves (moving along the axis).

lift check valve Working principle diagram

The function of this type of valve is to only allow the medium to flow in one direction and to prevent the flow of direction. Usually this kind of valve works automatically. Under the action of the fluid pressure flowing in one direction, the valve flap opens; when the fluid flows in the opposite direction, the fluid pressure and the self-coincidence of the valve flap act on the valve seat, thereby cutting off the flow.

Among them, internal thread check valve and butterfly check valve belong to this type of valve, which includes swing check valve and lift check valve. The swing check valve has a hinge mechanism and a valve disc like a door that rests freely on the inclined valve seat surface. In order to ensure that the valve disc can reach the proper position of the valve seat surface every time, the valve disc is designed in a hinge mechanism so that the valve disc has enough space for turning and makes the valve disc come into contact with the valve seat truly and comprehensively. The valve clack can be made of metal, or inlaid with leather, rubber, or synthetic covering, depending on the performance requirements. When the swing check valve is fully opened, the fluid pressure is almost unimpeded, so the pressure drop through the valve is relatively small. The disc of the lift check valve is located on the sealing surface of the valve seat on the valve body. Except that the disc can be raised and lowered freely, the rest of the valve is like a shut-off valve. The fluid pressure lifts the disc from the seat sealing surface, and the backflow of the medium causes the disc to fall back onto the seat and cut off the flow. According to the conditions of use, the valve disc can be an all-metal structure, or it can be in the form of a rubber pad or a rubber ring embedded in the disc holder. Like a shut-off valve, the passage of fluid through the lift check valve is also narrow, so the pressure drop through the lift check valve is larger than that of the swing check valve, and the flow rate of the swing check valve is restricted Rarely.

Stainless steel vertical check valve

July 31, 2020

Overview of Stainless steel vertical check valve:

H42W stainless steel flanged vertical check valve is a valve whose disc slides along the center line of the valve body. Pipeline vertical check valve is a new type of valve. It has the characteristics of simple structure, few parts, light weight, and good manufacturability. It is one of the development direc

lifting check valve (4)

tions of check valves. However, the fluid resistance coefficient is slightly larger than that of the swing check valve. Vertical check valves are widely used in various pipelines that need to prevent the medium from flowing back in the petroleum, chemical, pharmaceutical, and power industries. H42H can be equipped with spring or no spring according to vertical installation or horizontal installation.

Stainless steel vertical check valve H42W flange vertical check valve working principle:

H42W series vertical check valve can prevent the medium from flowing back and play the role of medium check. H42W stainless steel vertical check valve is open when the medium pressure at the inlet end is higher than the outlet end. Because under the pressure of the medium at the inlet end of the pipeline, the valve clack in the vertical check valve is pushed up to automatically open the valve. When the medium pressure at the inlet end is lower than the outlet end, the spring pushes the disc toward the valve seat to close the valve. Under the pressure, it will automatically close.

Troubleshooting of check valve

July 30, 2020

Troubleshooting of check valve:

double-wing-check-valve-3

1. The disc is broken
The reasons that cause the valve disc to break are:

The pressure of the medium before and after the check valve is close to balance and they are “see-saw” each other. The valve disc often beats against the valve seat, and the disc made of some brittle materials (such as cast iron, brass, etc.) is broken.

The preventive method is to use a check valve whose disc is a flexible material.

2. Medium backflow
The reasons for the backflow of the medium are:

①The sealing surface is damaged; ②Insert impurities.

Repairing the sealing surface and cleaning impurities can prevent backflow.

Selection criteria for check valves

July 30, 2020

Selection criteria for check valve:

The selection criteria for check valves are as follows:

double-wing-check-valve-3

1. In order to prevent the medium from flowing back, check valves should be installed on equipment, devices and pipelines;

2. Check valves are generally suitable for clean media, not for media containing solid particles and high viscosity;

3. Generally, horizontal lift check valves should be used on horizontal pipes with a nominal diameter of 50mm;

4. The straight-through lift check valve can only be installed in horizontal pipelines;

5. For the inlet pipeline of the water pump, a bottom valve should be used. The bottom valve is generally only installed on the vertical pipeline at the pump inlet, and the medium flows from bottom to top;

6. Compared with the swing type, the lifting type has better sealing performance and greater fluid resistance. The horizontal type should be installed on the horizontal pipeline, and the vertical type on the vertical pipeline;

7. The installation position of the swing check valve is not restricted. It can be installed on a horizontal, vertical or inclined pipeline. If installed on a vertical pipeline, the medium flow direction should be from bottom to top;

8. The swing check valve should not be made into a small-diameter valve, it can be made into a high working pressure, the nominal pressure can reach 42MPa, and the nominal diameter can also be large, the maximum can reach more than 2000mm. It can be applied to any working medium and any working temperature range according to the different materials of the shell and the seal. The medium is water, steam, gas, corrosive medium, oil, medicine, etc. The working temperature range of the medium is between -196–800℃;

all types of check valve and structures -code names-photos

9. The applicable occasion for swing check valve is low pressure and large diameter, and the installation occasion is restricted;

10. The installation position of the butterfly check valve is not restricted. It can be installed on a horizontal pipeline or on a vertical or inclined pipeline;

11. Diaphragm check valve is suitable for pipelines that are prone to water hammer. The diaphragm can well eliminate the water hammer caused by the backflow of the medium. It is generally used on low-pressure and normal temperature pipelines, and is especially suitable for tap water pipelines. Normal media work The temperature is between -12-120℃, and the working pressure is less than 1.6MPa, but the diaphragm check valve can achieve a larger diameter, and the maximum DN can reach more than 2000mm;

12. The spherical check valve is suitable for medium and low pressure pipelines and can be made into a large diameter;

13. The shell material of the spherical check valve can be made of stainless steel, and the hollow sphere of the seal can be wrapped with polytetrafluoroethylene engineering plastics, so it can also be applied to the pipeline of general corrosive media, and the working temperature is -101–150 ℃, its nominal pressure is ≤4.0MPa, and the nominal passage range is between DN200-DN1200;

14. When selecting a check valve for incompressible fluids, the required closing speed must be evaluated first, and the second step is to select the type of check valve that may meet the required closing speed;

15. The check valve for compressible fluid can be selected according to the similar method of check valve for incompressible fluid. If the medium flow range is large, the check valve for compressible fluid can be used A deceleration device, if the medium flow is stopped and started quickly and continuously, such as the outlet of the compressor, a lift check valve is used;

16. The corresponding size of the check valve should be determined, and the valve supplier must provide the data of the selected size, so that the valve size when the valve is fully opened at a given flow rate can be found;

17. For high and medium pressure check valves below DN50mm, vertical lift check valves and straight-through lift check valves should be used;

18. For low-pressure check valves below DN50mm, butterfly check valves, vertical lift check valves and diaphragm check valves should be used;

19. For high and medium pressure check valves with DN greater than 50mm and less than 600mm, swing check valves should be used;

20. For medium and low pressure check valves with DN greater than 200mm and less than 1200mm, wear-free spherical check valves should be used;

21. For low-pressure check valves with a DN greater than 50mm and less than 2000mm, butterfly check valves and diaphragm check valves should be used;

22. For pipelines that require relatively small water hammer impact or no water hammer when closed, slow-close swing check valves and slow-close butterfly check valves should be selected.

Classification of check valves

July 30, 2020

Classification of check valves:
The check valve that opens or closes by the force of the medium flow to prevent the medium from flowing back is

tilting disc swing check valve (6)

called a check valve. Check valves belong to the category of automatic valves, which are mainly used in pipelines where the medium flows in one direction, and only allow the medium to flow in one direction to prevent accidents.

Classified by structure:
According to the structure, it can be divided into three types: lift check valve, swing check valve and butterfly check valve:

1. Lift check valves are divided into two types: vertical and horizontal.

2. The swing check valve is divided into three types: single, double and multiple.

3. The butterfly check valve is straight-through.

The above-mentioned check valves can be divided into four types in connection form: threaded connection, flange connection, welding connection and wafer connection.

Classified by material:
1. Cast iron check valve

2. Brass check valve

3. Stainless steel check valve

4. Carbon steel check valve

5. Forged steel check valve

Classified by function:
1. DRVZ silent check valve

Stainless steel check valve
Stainless steel check valve
2. DRVG silent check valve

3.NRVR silent check valve

4. SFCV rubber flap check valve

5.DDCV double disc check valve

Tanghai Valve is the best manufacturer of check valve in China. We produce the best quality products with competitive low prices. Main products: butterfly valve, lug type butterfly valve, wafer type butterfly valve, U-type butterfly valve, double flange butterfly valve, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…)

Check valve and its working principle

July 30, 2020

What is check valve?

Check valve refers to a valve whose opening and closing parts are circular discs and rely on its own weight and medium pressure to generate actions to block the back flow of the medium. It is an automatic valve, also called check valve, one-way valve, return valve or isolation valve. The movement of the disc is divided into lift check valve and swing check valve. The lift check valve is similar in structure to the stop valve, but lacks the valve stem to drive the valve disc. The medium flows in from the inlet end (lower side) and flows out from the outlet end (upper side). When the inlet pressure is greater than the sum of the weight of the disc and its flow resistance, the valve is opened. On the contrary, the valve is closed when the medium flows back. The swing check valve has a disc that is incline

tilting disc check valve body (2)

d and can rotate around the axis, and its working principle is similar to that of the lift check valve. The check valve is often used as the bottom valve of the pumping device to prevent the backflow of water. The combination of check valve and stop valve can play a role of safety isolation. The disadvantage is that the resistance is large and the sealing performance is poor when closed.

Working principle of check valve:
Check valves can also be used to supply pipelines for auxiliary systems whose pressure may rise above the system pressure. Check valves can be divided into swing check valves (rotating according to the center of gravity) and lift check valves (moving along the axis).

The function of this type of valve is to only allow the medium to flow in one direction and prevent the flow in the opposite direction. Usually this kind of valve works automatically. Under the action of the fluid pressure flowing in one direction, the valve flap opens; when the fluid flows in the opposite direction, the fluid pressure and the self-coincidence of the valve flap act on the valve seat, thereby cutting off the flow.

Among them, check valves belong to this type of valve, which includes swing check valves and lift check valves. The swing check valve has a hinge mechanism and a valve flap like a door that rests freely on the inclined valve seat surface. In order to ensure that the valve clack can reach the proper position of the valve seat surface every time, the valve clack is designed in a hinge mechanism so that the valve clack has enough space for rotation and makes the valve clack truly and comprehensively contact the valve seat. The valve clack can be made of metal, or inlaid with leather, rubber, or synthetic covering, depending on the performance requirements. When the swing check valve is fully opened, the fluid pressure is almost unimpeded, so the pressure drop through the valve is relatively small. The disc of the lift check valve is located on the sealing surface of the valve seat on the valve body. Except that the disc can be raised and lowered freely, the rest of the valve is like a shut-off valve. The fluid pressure lifts the disc from the seat sealing surface, and the backflow of the medium causes the disc to fall back to the seat and cut off the flow. According to the conditions of use, the valve disc can be an all-metal structure, or it can be in the form of a rubber pad or a rubber ring inlaid on the disc holder. Like a shut-off valve, the passage of fluid through the lift check valve is also narrow, so the pressure drop through the lift check valve is larger than the swing check valve, and the flow rate of the swing check valve is restricted.

Detailed introduction of soft sealing butterfly valve-(2)

July 28, 2020

There are many types of soft-sealed butterfly valves, which can be divided into the following categories according to different forms:
Classified by structure
Classified by structure

(1) Center sealing butterfly valve

(2) Single eccentric sealed coal valve

ductile iron, DI, butterfly valve, manufacturer, center line, TH valve

(3) Double eccentric sealing butterfly valve

(4) Triple eccentric seal valve

Classified according to the sealing surface material:

(1) Soft sealing butterfly valve.

1) The sealing pair is composed of non-metallic soft material to non-metallic soft material.

2) The sealing pair is composed of a metal hard material and a non-metal soft material.

(2) Metal hard seal butterfly valve. The sealing pair is composed of a metal hard material to a metal hard material.

Classified according to the sealing form:

(1) Forced sealing butterfly valve

1) Elastic sealing butterfly valve. The specific pressure of the seal is generated by the valve plate squeezing the valve seat when the valve is closed, and the elasticity of the valve seat or valve plate

2) External torque sealing butterfly valve. The seal specific pressure is generated by the torque applied to the valve shaft

(2) Pressurized sealing butterfly valve. The specific sealing pressure is generated by the pressure of the elastic sealing element on the valve seat or valve plate

(3) Automatic sealing butterfly valve. The sealing specific pressure is automatically generated by the medium pressure.

Classified by work pressure:

(1) Vacuum butterfly valve. Butterfly valves whose working pressure is lower than the atmospheric pressure of the standard reactor.

(2) Low pressure butterfly valve. Butterfly valve with nominal pressure PN<1.6MPa.

(3) Medium pressure butterfly valve. Butterfly valve with nominal pressure PN of 2.5-6. 4MPa.

(4) High pressure butterfly valve. A butterfly valve with a nominal pressure PN of 10.0-80.0MPa.

(5) Ultra-high pressure butterfly valve. Butterfly valve with nominal pressure PN>100MPa.

Classified by working temperature:

(1) High temperature butterfly valve. t>450 C butterfly valve

(2) Medium temperature butterfly valve. 120 C＜t＜450 C butterfly valve

(3) Normal temperature butterfly valve. One 40C<t<; 120 C butterfly valve

(4) Cryogenic butterfly valve. One 100＜t＜一40 C butterfly valve

(E) Ultra-low temperature butterfly valve. t＜一100 C butterfly valve

Classified according to the connection method:

(1) Wafer butterfly valve

(2) flange butterfly valve

(3) lug butterfly valve

(4) Welded butterfly valve

Posts

What is double plate swing check valve

What is a Single-disc swing check valve

What is a single plate check valve

What is vertical check valve

Stainless steel vertical check valve

Troubleshooting of check valve

Selection criteria for check valves

Classification of check valves

Check valve and its working principle

Detailed introduction of soft sealing butterfly valve-(2)

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