Poor suction piping practices are a very common source of pump problems.  To insure proper operation it is very important to pay careful attention to the design of the suction system before the pump is installed.  A small amount of extra time and money invested in the pump system usually provides for better pump performance and longer periods between service requirements.

The suction line from the fluid source to pump should be as short and direct as possible.  Use either rigid piping, non-collapsible hose or a combination of both as circumstances warrant in your installation.  The suction pipe size should be at least one size larger than the pump inlet.  Long piping runs, low suction heads, or indirect pipe routing may require even greater oversizing of the suction line for proper operation of the pump.  In some cases it may be necessary to install a booster pump in the suction line of the pump to obtain sufficient pressure for the pump to operate.

The suction line must be laid out so that there are no high spots in the line where gas or air pockets could collect.  These pockets can make the pump difficult to prime and cause rough, erratic operation. A drain valve or plug should be installed at the low point of the suction line to allow for drainage during freezing conditions or for maintenance.

FMC Technologies recommends that all piping be supported independently of the pump.  By supporting the piping this way, vibrations are reduced and stress on the pump is kept to a minimum.  The use of elbows, nipples, unions, or other fittings should be minimized.  To help isolate mechanical and hydraulic vibrations, FMC Technologies  recommends the use of flexible hose connections between the pump and any rigid piping.  Make sure that all joint and connections are airtight.  Air leaks reduce the capacity of the pump and can cause cavitation and loss of prime.

Always insure that calculated system NPSHa exceeds pump NPSHr by at least 5 ft-H2O for proper operation of the pump.  NPSH requirements for each pump model are provided on the product data sheets available through FMC Technologies or your authorized FMC Technologies reseller.  FMC Technologies does not recommend using the pump in static lift conditions without prior approval.