Page 85 - Webster Service Manual

SPM Duplex Automatic Models
SPM Duplex Automatic units consist of two SPM Series
pump/motor assemblies and an electrical control panel.
They are designed for use in maintained pressure sup-
ply systems
if system pressure falls below a pre-
set level, the control automatically switches from the pri-
mary pump/motor unit to the secondary unit. If the backup
pump/motor unit also fails to reach or maintain preset
system pressure, the control also shuts of f the backup
A pump selector switch allows the two pump/motor units
to be manually alternated for even wear on each pump.
Pump pressures can be set at a range from 10 psi to
psi. See Correct Supply Line charts, for maximum
discharge head.
Tank to Pump Connections
Units should be set for two-pipe operation. Preferred
installation calls for a separate suction line from tank to
pump for each pump/motor unit. If system failure occurs
because of a gross leak in the suction line of the primary
unit, the second unit can still provide backup service.
The correct suction line size can be determined by
referring to the charts Generally , the return line should
be sized the same as the suction line. Low pressure
drop, swing type check valves can be installed in the
suction lines, assuring that pumps are full of oil, ready
for service. Check valves in return lines allow removal
of inactive pump for servicing. Use of shutoff valves in
return lines is not recommended.
Be certain all plugs
and connections are secure and leak-tight.
+ Not supplied by Webster