Differential Pressure Switch
Adjusting the Differential Pressure Switch
Adjust the PolyBlend differential pressure switch only if pressure
and flow
to the system
are adequate
.
The adjustment logic is the
opposite
of what you might expect.
The
PolyBlend differential pressure switches have a red light (on the left side)
that lights up whenever source water flow is too low and the polymer
pump is disabled. The pump stops pumping when the flow is too low.
Low flow may be from lack of incoming water or from too much back
pressure on the outgoing side.
Adjustment
System Reaction
1.
Turn the PolyBlend rotameter until water flow is at
maximum
on the flow gauge.
2. Screw in the differential pressure knob until the red
alarm
light goes on.
Polymer pump is
disabled.
3.
Back off the differential pressure knob until the red alarm
light goes off.
The pump starts again. ......
4.
4a.
If you want very close
control of flow, leave the
knob at this setting.
At this setting, any loss of
flow (as observed by the
rotameter) results in the
pump being disabled.
4b.
If you want to make the
system "more forgiving"
prior to shutdown,
continue
to turn the knob
another
1-2 turns.
The further you turn the
knob, the more How can be
lost before the pump is
disabled.
Step 4 determines how
"forgiving" the system is
before it shuts down due
to
inadequate flow.
5.
To test sensitivity and operation, turn off the water at the
source or the solution at the discharge.
The float in the flow meter will fall more for the control
knob
setting described in step 41) than, for 4a (above).
As the source or discharge
is turned off, the float in the
flow meter falls and the
pump is
disabled.
6.
Set the rotameter for the desired flow.
Retest (as in step 5).
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