Pump guidance “misleading”
11 Dec 2013
Firms trying to use electric motor efficiency ratings to sell wastewater pumps are guilty of misleading customers, the world’s largest pump manufacturer has claimed.
In an article appearing in the forthcoming Pumps & Valves inProcess supplement, Grundfos claims that it is impossible for wastewater pumps with an integral motor to be compliant with the standards typically used when demonstrating a pump’s energy efficiency.
Pump manufacturers who claim that their wastewater pumps are IE3 compliant are guilty of misleading consultants and end users
These standards are produced by the International Electrotechnical Commission (IEC) in relation to pumps’ electric motors, and are IE2 (high efficiency) and IE3 (premium efficiency).
“The question that has to be raised is whether a pump with an integrated motor designed for submergence in water, such as a wastewater pump, can be described as being IE2 or IE3 efficient,” says the article by the Danish firm.
“As the motor cannot be tested independently of the pump, largely because there is no standardised connection, no defined cooling system nor an established test method, the answer has to be “No”.”
Grundfos Management single and three-phase motor specialist Robert Bork Hansen said: “What makes the wastewater pump motor differ from the conventional IE3 motor are the bearings, mechanical seals and the absence of fan cooling. In wet installations, cooling is provided by the fluid in which the pump is submerged. By changing the bearings, adding a mechanical shaft seal and method of cooling, IE3 motor compliancy is negated.”
The article goes on to state that since it is impossible to claim that a wastewater pump containing an integral motor is IE2 or IE3 compliant, “Pump manufacturers who claim that their wastewater pumps are IE3 compliant are guilty of misleading consultants and end users”.
It goes on: “If a tender document specifies that wastewater pumps must comply with IE3, then it is impossible for any manufacturer to supply such a pump since there is no applicable standard available regarding the efficiency definitions for wastewater pumps with integrated motors.”
Grundfos’ suggested solution is to instead focus on the overall efficiency of the wastewater pump, rather than the type of electric motor that it uses, and in particular to look at hydraulics.
