Benefits of High Pump Efficiency

From the Pumpline Newsletter by Ross Mackay

Having conducted training programs for thousands of maintenance and operations people over the years, it has became apparent that many of the craftsmen that look after pumps have very little knowledge (if any) of the hydraulic workings of the pump. In fact, it has been suggested that such considerations are outside their functions and are usually left to some mystical person sitting “up in the office” somewhere.

Any time we start to discuss the Best Efficiency Point on a pump curve, a typical reaction would be that this is simply a question of energy savings and doesn’t have anything to do with maintenance.

Nothing could be further from the truth. Any time a pump is undergoing routine or other maintenance procedures, these are the times at which a quick check can be made of a couple of conditions.

1. How close to the BEP is that pump running. In other words, identify the BEP flow of the pump and the actual flow going through the pump during normal operation. The closer together these two values may be, the more efficient the pump. This means that you are simply using the least possible amount of power needed to operate that pump in the system.

2. Another factor is the setting of the discharge valves to determine if any are operating in anything but the full open position. If a valve is throttled, the energy being created by the pump is simply being wasted by being dissipated into the valve in the form of heat. This usually indicates that the pump is oversized and should be modified or replaced for a more efficient system.

It is also worth noting that, any pump that runs close to its Best Efficiency Point (BEP) will be much more reliable than it would be when operating further away from the BEP. At the BEP, the pump has zero chance of encountering problems such as excessive radial loads and suction or discharge recirculation; all of which contribute to premature seal and bearing failure.

So there is more than one benefit to be found from operating the pump in an efficient manner.

Until next month… keep on pumping.

Ross Mackay
Pumpline Newsletter