如何选用各种不同的止回阀
止回阀的选型标准内容如下：
1、为了防止介质逆流，在设备、装置和管道上都应安装止回阀；
2、止回阀一般适用于清净介质，不宜用于含有固体颗粒和粘度较大的介质；
3、一般在公称通经50mm的水平管道上都应选用立式升降止回阀；
4、直通式升降止回阀在水平管道和垂直管道上都可安装；
5、对于水泵进口管路，宜选用底阀，底阀一般只安装在泵进口的垂直管道上，并且介质自下而上流动；
6、升降式较旋启式密封性好，流体阻力大，卧式宜装在水平管道上，立式装在垂直管道上；
7、旋启式止回阀的安装位置不受限制，它可装在水平、垂直或倾斜的管线上，如装在垂直管道上，介质流向要由下而上；
8、旋启式止回阀不宜制成小口径阀门、可以做成很高的工作压力，PN可达到42MPa，而且DN也可以做到很大，zui大可以达到2000mm以上。根据壳体及密封件的材质不同可以适用任何工作介质和任何工作温度范围。介质为水、蒸汽、气体、腐蚀性介质、油品、药品、等。介质工作温度范围在 -196--800℃之间；适用场合是低压大口径，而且安装场合受到限制；
9、蝶式止回阀的安装位置不受限制，可以安装在水平管路上，也可以安装在垂直或倾斜的管线上；
Valve selection criteria as follows: 1, in order to prevent the media counter-current in the device, the device should be installed on the valve and piping; 2, the check valve for clean media generally should not be used to contain solid particles and the viscosity of the medium; 3, generally in the nominal level by 50mm pipe should be selected on the vertical lift check valve; 4, straight-lift valve in horizontal pipe and vertical pipe can be installed; 5, the import pipeline for water pumps, should be selected at the end of the valve, bottom valve is generally installed in the vertical pipe on the pump suction, and the media bottom-up flow; 6, compared with Swing Lift sealing, fluid resistance, horizontal pipe should be installed in horizontal, vertical mounted on the vertical pipe; 7, swing check valve is installed without restriction, it can be installed in horizontal, vertical or inclined pipeline, such as installed in the vertical pipe, the media flow to the bottom up; 8, Swing Check valves should not be made ??of small diameter, can be made very high work pressure, PN up to 42MPa, and the DN can be large, the maximum can reach more than 2000mm. According to the shell and sealing material can be applied to any work in different media and any operating temperature range. Medium is water, steam, gases, corrosive media, oil, medicines, etc. Medium temperature range of -196 - 800 ℃ between; 9, for large-diameter low-pressure situations, and limited installation of occasions; 10, the butterfly valve is installed without restrictions, can be installed in a horizontal tube on the road can also be installed in vertical or inclined pipeline;
