Why You Should Be Using Pressure Gauges

Centrifugal pumps are designed to operate within an "envelope" which is generally related to the best efficiency point on the pump performance curve.

For best performance and component life, the pump should run at between 80 and 110% of b.e.p. - best efficiency point. (70 to 120% is considered fair if this cannot be achieved).

If the pump is selected too far to the left of the b.e.p. recirculation will occur, first in the discharge and then in the suction. Efficiency of the pump will fall quickly because of this and there may be accelerated wear - particularly if the pump is handling solids.

As flow is reduced further, internal axial and radial forces increase and the pump might vibrate. Impeller, bearing, shaft and seal life can be reduced substantially.

Finally at very low flows there may not be sufficient cooling of the pump it may overheat and liquid in the casing vaporise. This may damage seals and in some cases lead to pump seizure. NPSH rises towards closed valve and cavitation damage might also occur.

When a pump duty is overestimated, it results in the system curve intersecting the performance curve too far to the right of b.e.p., and may be off the performance curve completely. Flow will be more than that required and there is a danger of cavitation damage which will drastically shorten the life of the pump.
 

Control valves, variable speed drive and changing impeller diameter can all be effective in maintaining operation in the best range. Pressure gauges on the suction and discharge of pumps will, by reference to the performance curve, confirm correct operation.

In addition, by taking a gauge reading at closed valve with the pump running (for a short time only) you will have an indication of its condition.  Reduced pressure will almost certainly mean wear or blockage in the pump.

If there is air in your system, this will make it inefficient and can damage your pump and installed equipment.  Pressure gauges will show fluctuating readings indicating that air is present.

Both analogue and digital gauges can be supplied by Pumpgear.co.uk. Competitive, first class quality and quick delivery.  Customisation is available - your company logo can be printed on the dial.  Special gauges, glycerine filled, food quality and chemical gauges are also readily available.