Issues regarding the selection of valves to prevent gas backflow in vacuum systems
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I am currently working on the gas piping for a vacuum system. Due to process requirements, it is necessary to prevent cross-contamination of different gas streams; therefore, swing check valves were chosen at the design stage. However, due to the low system pressure (the operating pressure of the check valve is around -10 kPaG), the company’s veterans said that it might be possible for gas not to be able to pass through. So I would like to ask everyone here: given this lower level of work pressure, what type of check valve would be suitable? Or, in addition to using check valves, are there any other methods within a vacuum system that can serve the same function as check valves?
A check valve opens based on pressure difference; if gas cannot pass through, it means the back pressure is too high and the pressure difference is insufficient?
The pressure drop of the check valve is not significant; as long as the vacuum pump has sufficient load, there is generally no issue in getting past it.
In the vacuum system, vertical lift-type check valves are installed to prevent backflow of air; is it still possible to experience leaks in the external seals?
Check valves are standard accessories; in addition, my design includes the use of emergency shut-off vacuum valves and pressure interlock controls to prevent the pump from stopping.
Is the check valve mentioned upstairs a standard accessory? When the vacuum level is greater than -0.095 MPa, it is simply impossible to open the check valve, and the resistance loss is high; it is possible that this very resistance is what prevents the vacuum level from dropping below 20 mmHg. The installation of the emergency shut-off vacuum butterfly valve should be interlocked with the pump’s start and stop operations, but not with pressure controls
Pay attention to the installation position of the swing check valve, as different pressure drops are required for horizontal and vertical installation.
The pressure drop of the check valve before the vacuum pump is very important