Simplex STS DAY TANK, Manual

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Overflow-
Return Pump
And Controller
Added To Day
Tank, Option
390
Normally the Day Tank operates automatically to control the fuel
level between the 50% and normal full level, which is set at the
position of the overflow or vent fitting on the tank. An overfill can
occur if the control switch is left in the Manual position, if there is
a leak in a control valve permitting gravity or siphon flow of oil
into the tank, or if there is a control failure. In the event of an
overfill, float switch FS4 will close, activating the High Level
Alarm L.E.D. lamp on the control panel. In addition, the fill pump
will be disabled. The tank should not fill above this point, which is
approximately 1.0” above the normal full level but 1.0 - 2.0” below
the top of the tank. With the addition of option 390, the overflow-
return pump will be activated by the overflow alarm circuit and
will operate as described below.
Above 70% level, float switch closes and arms the overflow-return
controller, illuminating the “overflow return armed” indicator and
enabling the overflow pump test push-button. Upon activation of
the overflow alarm by float switch FS4, as described above, the
over flow pump contactor will be energized, and the overflow
pump will run. The contactor is latched-in via 70% level float
switch and the tank will be pumped
down to the 70% level. This is
intermediate in the normal
operating range of 50% to full and
the tank should remain at this level;
the refill pump will not start until
the tank reaches the 50% level. As
the overflow pump is running, the
“pump running” L.E.D. will be
illuminated.
To test the overflow-return pump,
press the Test pushbutton. This
pushbutton is armed only above the
70% level, when the L.E.D. is
illuminated. The overflow pump
will pump-down the tank to the 70%
level. If desired, the tank can be
refilled to normal full by pressing
the test pushbutton on the control
panel.
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