PB3 User Instruction
Page 21 of 39
3.5.1 Suction and discharge piping
These units are furnished for a particular service condition. Changes in the hydraulic system may affect
performance adversely. This is especially true if the changes reduce the pressure at the suction or if the liquid
temperature is increased.
Suction and discharge piping should be of ample size, be installed in direct runs, and have a minimum of bends.
Eccentric reducer shall be flat on top (FOT).
It is desirable to have at least (7) diameter of straight pipe between the first elbow and the pump suction. Elbow
in the piping to pump’s suction nozzle should be of the long radius type.
Seven (7) diameters of straight pipe should be used between two elbows in series and the pump suction.
Elbows in more than one plane should not be used without splitters.
Splitters are placed in the elbow in the mean radius line perpendicular to the plane of the elbow.
Caution
Provision must be made to support piping external to the pump to prevent excessive
nozzle loads, maintain pump/driver alignment and avoid pipe- induced vibrations.
Install a check valve and a gate valve in the discharge pipe of the pump. When the pump is stopped, the check
valve will protect the pump against excessive pressure and will prevent the pump from running backward. The
check valve should be installed between the gate valve and the pump nozzle in order to permit its inspection.
The gate valve is also useful in priming and starting the pump.
Keep the suction pipe short and direct. Use a suction pipe equal to or one size larger than the pump suction
nozzle. Keep the suction pipe free of all air pockets. A spool piece should be installed in suction line so that the
suction screen may be installed and removed.
Caution
Operation at low flows results in pump power heating the liquid. A bypass may be
required to prevent vaporization and subsequent pump damage. Mechanical damage
may result from continuous operation at flows less the minimum flow of design
operating point.
WARNING
When pump is equipped with manifolded vent and drain lines, each line must be
equipped with an individual valve to prevent any liquid from a high pressure line
flowing into a low pressure line. These valves must be kept in the closed position
during pump operation.
3.5.2 Suction strainer
In a new installation, great care should be taken to prevent dirt, scale and welding beads from entering the
pump. Even when piping has been previously flushed, it is difficult to break loose the oxides and mill scale,
which will become free when the pipe heats and cools several times. PUMPIRAN pumps are provided with
running clearances ranging typically from 0.12 mm (0.005 in.) to 0.80 mm (0.030 in.), depending on the service
