Page 3 - Submittal Form - For Sizing

The SPM DUPLEX models consist of two pump/motor assemblies with a pre-piped, common discharge manifold.
One pump/motor unit operates continuously, with the second providing backup service if the main pump fails.
Either automatic (SPM-DA models) or manual (SPM-DM models) controls are available.
The duplex automatic series are designed specifically for buildings where a constant supply of oil must be assured:
hospitals, apartment buildings, schools and other commercial/industrial buildings. The SPM-DA models consist of
two identical supply pump and motor sets mounted on a rigid channel iron base. Central to the base is a pedestal
which supports the control panel. On the side of the control panel is a selector switch that identifies either Pump #1
or Pump #2 to serve as the lead pump set. The other pump set then automatically becomes to lag pump set.
Should the lead pump lose pressure, for any reason, it will automatically be turned off and the lag pump turned on.
Simultaneously, an audible alarm will be activated to notify as service person that a pressure failure has occurred
and attention must be given to the SPM-DA unit. The control panel is equipped with a lead-lag switch to permit
manual alternation of the pumps to provide even wear on each pump.
The duplex manual series is designed for commercial and industrial structures where an oil supply is required only
during occupancy, and a qualified person is always present to perform the manual switching. It is not recommended
for structures with water sprinkler systems that are unoccupied for long periods of time. The SPM-DM consists of
two identical supply pump and motor sets mounted on a rigid channel iron base. Central to the base is a pedestal
upon which is mounted a selector switch only. If the active pump set fails, it must manually be turned off and the
inactive unit turned on.
Motors on standard pump sets are 1725 RPM, single phase 60 hertz units and must be specified for operation at
or 230 AC volts. Single phase 50 hertz motors are available on special request. Special pump sets are also
available with 1725 RPM, three phase 50 or 60 hertz motors. Contact the factory for information. Both frequency
of operation and AC voltage must be specified (230 or 460 AC volts).
Many other features are available such as oil spill pans under pump sets, indicator lights, pressure regulating
valves, etc. Contact the factory at (502) 695-4400 for information on these features and others that may not be
The basic premise for the control of an automatic duplex system is that a faulty supply pump will not develop
adequate pressure to supply fuel oil. By continuously monitoring pressure and issuing an indication when a
decrease in pressure occurs, it is able to switch from the lead pump, which has developed a fault, to the lag pump.
Pressure monitoring is accomplished by using a Honeywell
Pressuretrol model L404F having a variable pressure
range (10-150 psi) and a variable differential range (10-22 psi).
A three position “SELECTOR” switch mounted on the right side of the control panel is used to select “PUMP 1” or
PUMP 2” as the lead pump. Center position on the selector switch turns the control unit “OFF”. Just below the
selector is a “TEST” push button. While the automatic duplex system is operating, pushing the test button will turn
off the lead pump and turn on the lag pump. At the same time an audible alarm signal is sounded. Switching the
selector switch to the “OFF” position and then back to the original setting will restore the control back to its original
operating condition.
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