2-6 motor. The pump is mounted on the floor near the
b. Controls and Instruments.
water tank to which the pump inlet is connected.
The pump outlet is connected through a filter to the water
(1) Electrical controls. Operation of the air
supply line in the laboratory compartment. At the top of
compressor is controlled by the air compressor circuit
the tank is a capped fill pipe and a curved vent tube.
breaker switch on the main control panel (fig. 1-4). The
The side of the tank is equipped with a quantity sight
motor starter-relay box is mounted on the utility
gage. Both pump and tank are provided with drain plugs.
b. Controls and Instruments.
(2) Pressure switch. A pressure switch is
located within the compressor to cut on and off
(1) Electrical controls. Operation of the water
automatically at the required pressures.
pump is controlled by the water pump circuit breaker on
the main control panel (fig. 1-4). The motor starter-relay
(3) Unloader pilot valve. An unloader pilot valve
box is located in the utility compartment.
automatically controls the unloaders on the compression
(2) Sight glass. The sight glass on the water
cylinders according to the predetermined setting of 80
tank is used to indicate the height of the water in the
psi (36.3 kg/sq cm) maximum and 60 psi (27.2 kg/sq cm)
The unloader pilot valve is
(3) Outlet valves. The water supply line has
connected to the tank pressure and actuates the
seven outlet valves, two on the left wall of the laboratory
compartment, four on the right wall, and one in the fume
(4) Safety valve. A safety valve, located on the
air-receiver tank, is set to blow off if the tank reaches the
(4) Tank gate valve. When closed, this valve
maximum working pressure of 100 psi. The valve
prevents water under pressure from flowing into the tank;
ordinarily requires no attention after being set at the time
when open, it provides a means of filling the water tank.
(5) Inlet gate valve. This valve, when open,
(5) Air pressure gage. The air pressure gage,
allows water to flow from the external source; when
located on the air compressor, shows the air pressure
closed, it prevents water from being pumped out.
maintained by the air compressor during operation.
(6) Pressure switch. A pressure switch located
(6) Air compressor gage. The air compressor
in the water supply line to the sink automatically breaks
gage, mounted on the control panel, shows the air
the electrical circuit to the pump when the sink faucet is
pressure within the air supply lines of the laboratory.
closed. The pump automatically starts when the faucet
c. Operation. The air compressor is designed to
operate through a pressure switch without damaging the
(7) Check valve. A check valve prevents water
air compressor or the piping and valves. However, if
under pressure from reaching the pump when the
continuous operation should occur, the pressure switch
external water supply is in use.
should be checked for malfunction. Operation of the air
(8) Air bleed valve. An air bleed valve is located
compressor is as follows:
on the top of the water tank to prevent pressure buildup
(1) Make sure all air supply line valves are
while pumping from the tank or filling it. An air bleed
valve is located on top of the sight gage to prevent
on control panel to ON position.
(9) Drain plug. Both the water tank and the
(3) When required pressure within the air
water pump are equipped with drain plugs to remove
receiver tank is reached, open the compressed air
water from the system during transit or storage.
release valve to the air supply lines.
compressor circuit breaker in the OFF position.
(1) Open the sight gage air bleed valve and
2-5. Water Pump.
check the water level in tank. Replenish if necessary.
(2) Make certain all valves on the water supply
a. Description. The water pump, storage tank, and
and water return lines are closed.
other units that make up the pressure water system fig.
2-3) are located
on the floor
at the rear
of the utility
compartment. The water pump is a centrifugal pump
vac, single-phase electric