The purpose of using a check valve is to prevent the reverse flow of the medium, and a check valve is generally installed at the outlet of the pump. In addition, a check valve is installed at the outlet of the compressor. In short, in order to prevent the reverse flow of the medium, check valves should be installed in equipment, devices or pipelines.
Generally, vertical lifting check valves are selected on horizontal pipelines with a nominal diameter of 50mm. Straight-through lift check valves can be installed on both horizontal and vertical lines. The foot valve is generally only installed on the vertical line of the pump inlet, and the medium flows from bottom to top.
The swing check valve can be made with a high working pressure, PN up to 42MPa, and DN can also be very large, up to more than 2000mm. Depending on the material of the housing and seals, any working medium and any operating temperature range can be applied. The medium is water, steam, gas, corrosive medium, oil, food, medicine, etc. The operating temperature range of the medium is between -196~800°C.
Swing check valves can be installed in unlimited locations and are usually installed on horizontal lines, but can also be installed on vertical or inclined lines.
The butterfly check valve is suitable for low pressure and large diameter, and the installation situation is limited. Because the working pressure of the butterfly check valve can not be very high, but the nominal diameter can be very large, it can reach more than 2000mm, but the nominal pressure is below 6.4MPa. The butterfly check valve can be made into a pair clamp type, which is generally installed between the two flanges of the pipeline, and adopts the form of pair clamp connection.
The butterfly check valve can be installed in an unlimited position and can be installed on a horizontal, vertical or inclined line.
Diaphragm check valves are suitable for pipelines that are prone to water hammer, and the diaphragm can well eliminate water hammer when the medium flows against the flow. Because the working temperature and use pressure of diaphragm check valves are limited by diaphragm materials, they are generally used in low-pressure normal temperature pipelines, especially suitable for water pipelines. Generally, the working temperature of the medium is between -20~120°C, and the working pressure is <1.6MPa, but the diaphragm check valve can achieve a larger caliber, and the DN can be up to more than 2000mm.
Diaphragm check valves have been used more in recent years because of their excellent waterproof performance, relatively simple structure and low manufacturing cost.
Ball check valve because the seal is a ball covered with rubber, so the sealing performance is good, the operation is reliable, and the water shock resistance is good; And because the seal can be a single ball, or can be made into multiple balls, so it can be made into a large diameter. However, its seals are hollow spheres coated with rubber, which are not suitable for high-pressure pipelines, only suitable for medium and low-pressure pipelines.
Since the housing material of the ball check valve can be made of stainless steel, and the hollow ball of the seal can be coated with PTFE engineering plastic, it can also be used in the pipeline of general corrosive media.
The working temperature of this type of check valve is between -101~150°C, its nominal pressure is ≤4.0MPa, and the nominal diameter range is between 200~1200mm.
Post time: Apr-23-2023