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Pump users observe maximum working pressure when selecting pumps. But, they should also consider suction pressure to ensure that the maximum working pressure is not exceeded. Exceeding the maximum working pressure can cause injury or damages.

 

The suction pressure plus the maximum differential pressure of the pump indicates what working pressure the pump could be producing. With multistage vertical booster pumps, suction pressure must be observed more closely than single stage horizontal pumps.

 

A vertical pump produces flow upwards through the stages and then down the outside of the stages to the discharge. In doing so, forces are produced both upwards, as with low differential pressure, and downward, when the differential pressure increases. Vertical motors are designed to take up the thrust loads for higher pressures that are typically associated with multistage verticals.

 

But they are not capable of high upward pressures as seen in low pressure in relation to the suction. Operating a vertical booster with high suction pressure with low differential pressure causes an upthrust load which is transferred to the motor shaft. This can cause bearing failure in the motor.

 

Because of the possible damage to the motor, suction pressure limits are applied to the pump data to ensure that excessive upthrust loads do not transfer to the motor. Charts are available from manufacturers data with maximum suction pressure. The maximum suction pressure should be considered when designing the pump for an application. Consult the manufacturer before risking a failure.

 

The pressure maximum varies with the number of stages as seen in the chart along with maximum working pressure. Download the Webtrol NV Series Maximum Working Pressure and Maximum Suction Pressure Chart. Following these limits will increase the pump life as well as protect for serious injuries.

 

 

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