如何選用各種不同的止回閥
止回閥的選型標準內容如下：
1、為了防止介質逆流，在設備、裝置和管道上都應安裝止回閥；
2、止回閥一般適用于清凈介質，不宜用于含有固體顆粒和粘度較大的介質；
3、一般在公稱通經50mm的水平管道上都應選用立式升降止回閥；
4、直通式升降止回閥在水平管道和垂直管道上都可安裝；
5、對于水泵進口管路，宜選用底閥，底閥一般只安裝在泵進口的垂直管道上，并且介質自下而上流動；
6、升降式較旋啟式密封性好，流體阻力大，臥式宜裝在水平管道上，立式裝在垂直管道上；
7、旋啟式止回閥的安裝位置不受限制，它可裝在水平、垂直或傾斜的管線上，如裝在垂直管道上，介質流向要由下而上；
8、旋啟式止回閥不宜制成小口徑閥門、可以做成很高的工作壓力，PN可達到42MPa，而且DN也可以做到很大，zui大可以達到2000mm以上。根據殼體及密封件的材質不同可以適用任何工作介質和任何工作溫度范圍。介質為水、蒸汽、氣體、腐蝕性介質、油品、藥品、等。介質工作溫度范圍在 -196--800℃之間；適用場合是低壓大口徑，而且安裝場合受到限制；
9、蝶式止回閥的安裝位置不受限制，可以安裝在水平管路上，也可以安裝在垂直或傾斜的管線上；
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;
