28
SF
-
2: ADJUST SHURFLO PRESSURE SWITCH
The Shurflo feed pumps are equipped with a high pressure cut out switch (EL
-
FP
-
PS). This is
the small black unit on the end of the wetted end of the pump head (PL
-
PMP
-
SFPH) where the
two
red wires connect. If the pressure switch is not properly adjusted the pump may cut out
each time the Clark pump cycles and the feed pressure spikes. When this happens the produc-
tion will drop and an unusual noise will be heard when operating on two pumps, but the sys-
tem will function normally during one pump operation on either pump. The points in the
switch will fail fairly fast if set too low because of the constant arcing from cutting out each
time the Clark pump shifts.
For all systems except the Gulfstream the feed pump
pressure switches should be set as fol-
lows.
On the very center of the switch is a small
5/64”
Allen screw.
Run the system on pump
one and close the brine discharge valve (1/2 way 90 deg), or kink the discharge hose, to block
the flow.
Watch the pressure gauge and adjust the pressure switch to shut off at 125 psi.
Re-
peat for pump two. Turn the Allen screw clockwise to increase the cut off set point.
Gulfstream models could experience seal failures in the manifold if pressurized too high. For
this reason the pump should be removed from the system and the switch adjusted using a
separate pressure gauge. If replacing a feed pump or pump head for a Gulfstream model ar-
range to preset the switch before installation.
Pressure Switch
Adjusting Screw
