Check Valve Applications
The purpose of using check valve is to avoid the backflow of medium, generally in the outlet of the pump should be installed check valve. In addition, the outlet of the compressor should also be installed check valve. In summary, in order to avoid the backflow of the medium, in the equipment, installation or pipeline should be installed check valve in general in the nominal diameter of 50mm of the horizontal pipeline are selected vertical lift check valve. Straight lift check valve in the horizontal pipeline and straight pipeline can be installed. Bottom valve is generally installed only in the pump inlet of the heavy straight pipeline, and the media flow from the bottom up. Swing check valve can be made into a very high working pressure, PN up to 42MPa, and DN can also be very large, up to 2000mm or more. Depending on the material of the shell and seal, it can be applied to any working medium and any working temperature scale. The medium is water, steam, gas, corrosive medium, oil, food, medicine, etc. Medium working temperature scale between -196 ~ 800 ℃ swing check valve installation position is not constrained, usually installed in the horizontal pipeline, but also can be installed in straight pipeline or inclined pipeline.
Butterfly check valve is suitable for low-pressure large diameter, and the installation occasion is constrained. Because the butterfly check valve working pressure can not be very high, but the nominal diameter can be very large, can reach more than 2000mm, but the nominal pressure are below 6.4MPa. Butterfly check valve can be made into a pair of clamping type, generally installed in the pipeline between the two flanges, the choice of clamping articulation. Butterfly check valve installation position is not constrained, can be installed in the horizontal pipeline, can also be installed in the straight pipeline or inclined pipeline. Gap check valve is suitable for easy to produce water strikes on the pipeline, the gaps can be good to eliminate the water strikes when the media backflow. Because of the working temperature and pressure of the gland check valve by the gland material constraints, generally used in low pressure normal temperature pipeline, especially suitable for water pipeline. General medium working temperature between -20 ~ 120 ℃, working pressure <1.6MPa, but the barrier check valve can be larger caliber, DN can be more than 2000mm. Gap type check valve because of its excellent performance of water strike, structure and relatively simple, and low production cost, so in recent years the use of more. Spherical check valve because the seal is covered with rubber spheres, so the sealing performance is good, reliable operation, good water resistance; and because the seal can be a single ball, and can be made into multiple balls, so it can be made into a large diameter. But its seals are rubber-coated hollow spheres, not suitable for high-pressure pipelines, only for low-pressure pipelines. Because the shell material of the spherical check valve can be made of stainless steel, the hollow sphere of the seal can be covered with PTFE engineering plastic, so in general corrosive media on the pipeline can also be used. The working temperature of this type of check valve is between -101~150℃, its nominal pressure ≤ 4.0MPa, nominal diameter scale between 200~1200mm.
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