Liquiflo
Installation, Operation & Maintenance Manual
Poly-Guard
®
Series MAG-DRIVE Gear Pumps
Models P1 thru P9, Close-Coupled
8
Section 3: Pump & Motor Installation
3.1
Installation of Pump, Motor & Base
Refer to the Hydraulic Institute Standards for proper installation procedures of the base, pump and motor.
1)
The pump inlet should be as close to the liquid source as practical and preferably below it.
Even
though gear pumps have self-priming and lift capability, many issues can be avoided with a flooded suction
arrangement.
NOTE:
The Poly-Guard Series pumps are close-coupled and no alignment procedures between the pump and motor are
required.
3.2
General Piping Requirements
Refer to the Hydraulic Institute Standards for piping guidelines.
1)
All piping must be supported independently and must line up naturally with pump ports.
2)
Piping that handles both hot and cold liquids require proper installation of expansion loops and joints so that
thermal expansion of the piping will not cause misalignment.
3)
Suction and discharge piping should be the same size or larger than the inlet and outlet ports.
This is
especially important for viscous services when the pipe diameter has a large effect on friction losses and
NPSH available.
4)
Piping runs should be designed to minimize friction losses.
The suction line should be as short and
direct as possible, especially for viscous fluids and/or high flow rates. Sharp bends or restrictions in the piping
should be avoided. Long sweep elbows should be used when turns are required. Valves should be ball type,
which offer minimal resistance to flow when fully open.
5)
The piping should be arranged to allow the pump to be flushed and drained prior to the removal of the pump for
servicing. Valves and unions should be installed to allow the pump to be isolated during maintenance.
6)
Gasket materials used with flanged connections must be chemically and thermally compatible with the fluid and
operating temperature.
7)
The piping system should be thoroughly cleaned prior to installation of the pump.
3.3
Relief Valves
A positive displacement pump should have a pressure relief valve (PRV) installed in the discharge line
.
Operating a gear pump against a closed discharge valve will result in over-pressure and likely failure of the pump or
system. Install the relief valve between the pump discharge port and the discharge isolation valve. Ideally, the relief
valve should bypass the discharge line back to the supply tank. Where this is not feasible, piping the relief valve back
to the suction side of the pump will prevent immediate pump failure from over-pressure. However, continuously
running in this condition will cause heating of the fluid.
Caution!
Do not use the pump to support the piping or allow the piping to apply stress to
the pump ports. This can distort the alignment of the pump housing with internal
parts and lead to rapid wear or malfunction.
