Check Valve

Check Valve

Check valves are two-port valves, meaning they have two openings in the body, one for fluid to enter and the other for fluid to leave. Check Valves are often used with some types of pumps, such as diaphragm pumps, metering pumps, pumps for chromatography and pumps that supply water to water slides. In addition, they are extensively applied in many fluid systems such as those in chemical and power plants, and in many other industrial processes. Available in a wide range of sizes, costs and standards, check valves have a wide variety of applications. Topper boasts various types of check valves with top-notch quality and excellent performance such as API 6D/BS 1868 Swing Check Valve, API 602 Check Valve and API 594 Check Valve.

Working principle and application of check valve

Check valve, also known as one-way valve, works on the basis of the pressure difference of the fluid itself to realize the function of automatically preventing the fluid from flowing backwards. Check valve is mainly composed of valve body, disc and valve seat.

When the fluid flows into the check valve according to the normal flow direction, the pressure of the fluid will push the disc, overcome the resistance of the disc itself such as gravity and possible friction, and make the disc open, so that the fluid can smoothly pass through the check valve and flow to the target position. At this time, the disc is separated from the valve seat, and the fluid channel is unobstructed.

However, when the fluid has a reverse flow trend, that is, the fluid tries to reversely flow into the inlet end from the outlet end of the check valve, the pressure of the reverse flow fluid will act on the valve disc, which will make the valve disc close quickly and closely adhere to the valve seat, thus cutting off the reverse flow channel of the fluid and preventing the fluid from flowing backwards. This automatic response makes the check valve effectively prevent fluid from flowing backwards in the pipeline system without external power driving.

Check valves are widely used in many fields. In the water supply and drainage system, the check valve is installed on the outlet pipe of the water pump. When the water pump stops working, prevent the water in the pipeline from flowing back to the pump, avoid damage to the pump, and keep the water pressure in the pipeline system stable at the same time. In the water supply system of high-rise buildings, because the floors are high and the water pressure changes greatly, the check valve can ensure that the water can only flow in one direction from the low floors to the high floors, prevent the water from flowing backwards due to pressure fluctuation, and ensure the normal water supply of each floor.

In the petrochemical industry, check valves are used for conveying pipelines of various oil products and chemical raw materials. For example, in the crude oil pipeline in the refinery and the reaction material pipeline in chemical production, the check valve can prevent the material from flowing back due to pipeline pressure fluctuation, equipment failure and other reasons, avoid the mixing of different materials, and ensure the safety and stability of the production process. In some inflammable and explosive chemical medium conveying systems, the reliable operation of check valves is very important to prevent accidents such as fire and explosion.

Install check valves in steam pipelines and water supply pipelines in power industry and thermal power field. In the steam pipeline, the check valve can prevent the steam from flowing backwards when the steam turbine stops, and avoid damaging the blades of the steam turbine. In the water supply pipeline, the check valve ensures that the boiler feed water can only flow into the boiler in one direction, so as to prevent the water from flowing backwards due to pressure fluctuation and other reasons during the operation of the boiler, which will affect the normal operation of the boiler. In the hydropower industry, a check valve is usually installed on the inlet pipe of the turbine of a hydropower station to prevent the water from flowing backwards when the turbine stops or fails, thus causing damage to the turbine and related equipment.

In the pipeline system of ships, check valves are used in many aspects such as fuel system, seawater system and fresh water system. In the fuel system, the check valve is used to prevent the fuel from flowing backwards when the oil pump stops working or the pipeline pressure changes, so as to ensure that the engine can obtain the fuel supply continuously and stably. In seawater system and fresh water system, check valve can prevent seawater or fresh water from flowing backwards due to turbulence and pressure change during the navigation of the ship, and ensure the normal operation of the ship and the domestic water demand of the crew.