INSTALLATION
NA Series Operating & Instruction Manual
Page 13
AVOID PUMPING LIQUIDS
CONTAINING
SUSPENDED SOLIDS
A check valve and gate valve should be installed as close as possible to the pump discharge nozzle. The
check valve is installed to protect the pump from excessive back pressure or reverse flow rotation, and
to prevent back flow into the pump during shut down. The discharge (gate) valve is used to regulate the
flow. The check valve should be installed between the pump and the discharge valve to allow the pump
to be removed from service without emptying the discharge line.
A pressure gauge should be installed on the discharge side of the pump as close as possible to the
discharge nozzle.
Prior to starting the pump it is important to flush the piping to make sure that the system is free of
solids such as pipe scale, welding beads, and dirt. If possible a TEMPORARY START-UP STRAINER with
a 40 mesh screen should be installed in the suction line.
BE VERY CAREFUL
not to allow the temporary strainer to become plugged, causing low inlet pressure
with cavitation or dry running. A pressure gauge should be installed on either side of the temporary
strainer to measure the pressure drop across it. If there is any risk of ingestion of solids during normal
operation, once the pump has been successfully commissioned, a PERMANENT INLET STRAINER
should be fitted in the inlet line.
Standard AxFlow pumps are designed to handle clean liquids. Unless specifically agreed prior to
purchase of the pump from your supplier, suspended solid matter must be kept out of the pump by a
suitable inlet strainer. The strainer mesh size should be less than 0.5mm, with an open surface area at
least 2.5 x nominal cross-sectional area of pump inlet bore. The strainer must be inspected regularly
and cleaned when necessary.
