Installation
Ampco Pumps Company
Page 9
Ampco Pumps Company ZP3 Manual M-004 Rev A 10.15
Check/ Isolation/ Relief Valves
Check valves should be used on the inlet side for any application when the product is lifted
(Figure 8). This is to ensure a full inlet and is especially important with low-viscosity fluids. If
the system has liquid under a vacuum, such as closed tank applications, it is important to have
a check valve on the discharge side to prevent backflow during initial start-up (Figure 9).
Figure 8: Check Valve (Inlet Side)
Figure 9: Check Valve (Discharge Side)
When shut down time is not possible, a bypass system may be installed with a backup pump in
parallel series to allow production to continue while maintenance is performed on the down
pump. Isolation valves may also be used on both the inlet and discharge sides of the pump to
shut down the flow of product to the pump. This will allow for maintenance and removal of the
pump without draining the entire system and risking the loss of product.
CAUTION:
Ampco’s ZP positive displacement pumps are designed with
extremely tight tolerances allowing only low slip internally between rotors and
pump housing. DAMAGE will occur if the pump is operated with discharge or
inlet lines closed. DO NOT operate pump with lines closed.
In order to prevent damage to the pump, it is recommended a relief valve be installed on the
pump’s discharge side. The relief valve can either divert flow into a drain or back to the inlet
side (Figure 10).
Figure 10: Relief Valve Examples
Check Valve
Foot Check Valve
Check Valve
Closed Tank
