TM 10-4610-215-24
TM 08580A-24/2
2-53. HIGH- AND LOW-PRESSURE SWITCH.
a. General. The ROWPU is equipped with two switches that will shut off the unit when operating pressures
reach certain limits. The high–pressure switch shuts off power to the unit when the pump discharge pressure
reaches 1250 pounds per square inch (psi) (88 kg/cm2). It also turns on the R.O. PUMP HIGH–PRESSURE
warning lamp. This switch is mounted on the back of the control panel at the upper right side.
The low-pressure switch cuts off power to the unit when the pump suction pressure drops below 10 psi (0.7
kg/crop), and turns on the R.O. PUMP LOW–PRESSURE warning lamp. This switch is mounted on the back of
the control panel at the upper left. This paragraph describes removal, inspection, cleaning, repair, and installation
of the high–pressure and low–pressure switches.
b. Removal of High–pressure Switch. (Figure 2–56)
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
WARNING
ELECTRICAL HIGH VOLTAGE
Electricity can cause serious injury or death. Be certain that all
power is removed before performing maintenance on electrical
equipment.
ROWPU piping and equipment can contain extremely high
pressure during and after operation. If this pressure is not
relieved before working on these pipes or equipment, serious
injury or death may occur. Be sure to open all drains and vents
before beginning any disassembly.
Open VENT VESSELS valve and VENT PULSE DAMPENER valve.
Remove four screws (1) from high–pressure switch (11), gasket (3), and cover (2).
Remove cover (2) and gasket (3) from high-pressure switch (11).
Remove sealing grip (4) from high-pressure switch (11) in accordance with paragraph 2-63.
Unscrew coupling nut and disconnect pressure tube (5) from elbow (6).
Remove elbow (6) from high–pressure switch (11).
Remove two nuts (7), two lockwashers (8), and two flat washers (9) from screw (10).
Remove two screws (10) from high-pressure switch (11) and control panel.
Remove high–pressure switch (11) from control panel.
c. Removal of Low–Pressure Switch. (Figure 2–57)
(1) Open VENT CARTRIDGE FILTER valve.
(2) Remove four screws (1) and four lockwashers (2) from low-pressure switch (11), gasket (4), and
cover (3).
(3) Remove cover (3) and gasket (4) from low-pressure switch (11).
(4) Remove two screws (12) from terminal lugs (13) and switch (14).
(5) Remove sealing grip (5) from low-pressure switch (11) in accordance with paragraph 2-63.
(6) Unscrew coupling nut and disconnect pressure tube (6) from elbow (7).
(7) Remove elbow (7) from low-pressure switch (11).
(8) Remove two nuts (8) and two lockwashers (9) from screw (10).
(9) Remove two screws (10) from low-pressure switch 11) and control panel.
(10) Remove low-pressure switch (11) from control panel.
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