There are many reasons for the reduction of the air volume of the water ring vacuum pump. The common ones are: not reaching the rated speed (for example, when using a diesel engine as a power engine), excessive end and clearance, leakage of the stuffing box, insufficient water supply, heating of the liquid ring, The radial clearance of the single-acting pump is too large and scale is too large.

Among the above reasons, the excessive end clearance (ie the axial clearance of the single-acting pump) is the most important and common cause of insufficient air volume. If the position of the impeller on the pump body is not inclined, that is to say, the excessive end face clearance is not caused by the abrasion between the impeller and the side cover, then the excessive gasket should be removed.

Also, for single-acting pumps, the larger leakage of air volume is the radial gap between the impeller wheel load and the water ring. If this gap is too large, the air volume will be reduced too much. For this reason, supplementary water can be injected into the pump body or side cover corresponding to the radial gap to fill the excessive radial gap. At this time, the pressure of the supplementary water should be above 1.2 kg/cm2, otherwise it will not be able to enter. These should be considered in the design.

When hard water with higher hardness is used, the scaling phenomenon is very serious, and the scale on the blades will thicken, which will inevitably reduce the effective space. In addition, some of the suction and exhaust holes will be blocked, causing the air volume to decrease. The best way to get rid of limescale is to soften hard water before using it. For the scaled parts, the influence of scale can be reduced by mechanical methods (shoveling off the scale) or rinsing with hydrochloric acid (after rinsing with hydrochloric acid, the residual hydrochloric acid must be rinsed with water).