Liquid Ring Vacuum Pump in low vacuum of causes

The decrease of vacuum degree of liquid ring vacuum pump will lead to the decrease of vacuum degree of condenser, which will directly affect the operation economy of the unit. It is of great significance to ensure the output of liquid ring vacuum pump for safe and economic operation. This paper introduces two phenomena in this phenomenon and puts forward solutions.

There are two reasons for this phenomenon: there is something wrong with the liquid ring vacuum pump itself or the leakage of gas due to the poor tightness of the pipeline system.

In order to determine the cause, for the vacuum pump, cut off the suction system pipe, connect the intake pipe of the water ring vacuum pump directly with the closed container for the experiment, for the compressor, cut off the pipe of the compression system, and connect the exhaust pipe of the pump directly with the closed container for the experiment.

After the pump is connected with the closed vessel, start the liquid ring vacuum pump. If the pressure and vacuum do not change after 15-20 minutes, clarify that there is something wrong with the pump itself. If the pressure and vacuum gradually increase and reach the normal value, clarify that the tightness of the pipeline system is not good, so that the gas leaks. If the pressure and vacuum are higher than ever, but not reach the normal value, explain There are problems with both the open pump and the piping system.


A simple experimental method in the field is to close the valve close to the suction port (for the vacuum pump) or the valve of the exhaust pipe (for the compressor), start the liquid ring vacuum pump, investigate the change of the vacuum gauge or the pressure gauge of the exhaust pipe close to the suction port, and find out the cause of the fault. Using this method, it is necessary to ensure the reliability of valve sealing. If the problem lies in the pipeline system, it can find out the place of gas leakage through pressure test.

The experiment can be carried out at 1.5-3 atmospheric pressure. After tightening all connecting bolts, apply soap solution to the places with simple air leakage, such as the places with air holes and cracks on the flange, threaded joints, welding places and pipes. If these local leaks, the soap solution will have a big bubble.

For places with small air leakage, shellac (i.e. dry paint), propylbenzene resin paint, putty and other mortar or coating can be used for air leakage. But these are temporary emergency measures. The reliable and long-term way is to braze the metal at the air leakage. For places with large air leakage, it is to replace with new parts. If conditions do not allow, it is necessary to adopt repair welding. The local air leakage often occurs at the joint of the pipe flange, and the candle can be used to approach the joint. If the candle is drawn to the joint or shakes indefinitely, the air leakage is clarified here. Since the connecting bolt has been tightened before the experiment, the leakage shows that the gasket is damaged or not properly. It is necessary to replace the gasket or adjust the thickness of the gasket.

At the same time, the reason of low vacuum degree is that the disc impeller of liquid ring vacuum pump has large wear clearance, blockage, insufficient circulating water, system air leakage, slow speed and large difference in position. This situation also needs specific analysis. This reason is for reference only. Contact after-sales personnel if there is a problem.

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