Pump valves do not open and close the reasons for speed and the valve can not close the treatment
Release Time：
2013-11-13
Why do not open and close the valve quickly?
The rapid opening and closing of the valve on the pipeline will produce the phenomenon of water impact, and a water impact pressure value is generated at the section of the pipe immediately adjacent to the valve.
According to calculations, the liquid flow rate of the pipeline every change of 1m / s, the liquid pressure value can reach 1MPa, not only this pressure value is also in the form of water shock wave from the pipe section immediately adjacent to the valve to close to the speed of sound propagated upstream (sound in the water speed of 1500m / s, in the gasoline speed of 1100m / s), it and the original pressure at various points along the pipeline superimposed, it is may reach the level of rupture of the pipe.
Slowly, gradually open and close the valve, because in the instantaneous time, the speed change is small, the resulting initial pressure value is also small, and due to the extension of time, the water strike wave propagated upstream, and will produce a reflected wave, thereby offsetting the pressure of the initial water strike, so as to avoid the pipeline overpressure accident.
The valve does not close the treatment method?
1) The reason: there are debris in the medium, solid particles mat between the valve flap and the valve seat. Stem and valve valve connection is not good, so that the valve and the valve seat deflection can not be tight contact.
2) Treatment: to ensure the cleanliness of the medium, close the valve, such as found when the valve flap has a pad plug phenomenon, do not force hard off, can be used to quickly switch a few times, so that the pad plug washed out. Often to the valve stem and stem nut with lubricant, to ensure that the valve switch flexible.
What are the reasons and treatment methods for the valve not opening and closing?
1) cause: the stem and stem nut between the debris or poor engagement, stem and valve flap detachment, stem and stem nut rust, valve flap too much force and packing pressure is too tight.
2) Treatment: frequent lubrication and removal of debris to the stem and stem nut; stem and valve detachment, should be disassembled and overhauled; valve flap force is too large, when the pressure is reduced to open the valve.
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