Check out are the mechanical seals and the impeller, which are generally the first two parts to break down if and when there is a problem. The mechanical seal protects the impeller from wear, and can greatly increase overall pump life. Quality centrifugal pumps generally have self-lubricating carbon ceramic mechanical seals, and semi-trash and trash pumps have self-lubricating silicone carbide seals. These are the best seals to combat the wear caused by repeated use, and also keep the pump from leaking.
A cast iron impeller is also a necessity in pumps that will frequently be transporting solids. The impeller on some models is plastic, and may not stand up well over time. In addition, when buying a trash pump, make sure the pump has a wear plate to act as a buffer between the impeller and volute. This piece prevents solids from passing through the pump.
The pump housing is available in a variety of different materials. Higher quality housing is made of stainless steel or, in the most sturdy pumps, die-cast aluminum. While this type of housing may cost slightly more at the initial purchase, the extended life it will afford the pump will more than make up for the money saved buying a housing that is plastic.
The strainer keeps oversized debris from entering the intake hose and causing damage to the pump. Again, look for a metal strainer, since plastic pieces will usually crack or break over time, and won't keep unwanted debris out of the pumps hoses, causing them to become plugged.
Just as with other pieces of construction equipment, pump quality can vary greatly from one to the next. And although pumps are typically used for one simple task – moving water from point A to point B – a quality pump is clearly a wise investment, and one that will bring dependability and a greater return over time.