A
Operation
Figure 22 shows a cross section of the water inlet valve in its closed position and Figure 23 shows it in its open
position The water pressure at B and C has equalized because the bleed hole opening permits water to flow from
B to C Pressure at A is atmospheric (Figure 2.2)
The valve remains closed because the higher water line pressure at C is greater than the atmospheric pressure at
A. When the solenoid coil is energized by the timer, the plunger is withdrawn from the diaphragm opening Water
in compartment C wilt then escape through the diaphragm opening causing the pressure in the compartment to fall
to almost atmoshpheric pressure, The higher water line pressure at B forces the diaphragm away from its seat,
opening the valve Water then flows through the screen under the diaphragm and out the valve.
PLUNGER
HOLE
LINE WATER PRESSURE
WASHER
ATMOSPHERIC PRESSURE£ B
FIGURE22
CLOSEDPOSITION
PLUNGER
DIAPHRAGM
B -FLOW WASHER
FIGURE23
OPEN POSI'[ION
When the solenoid releasesthe plunger, the hole in the center of the diaphragm is sealed. Water then flows through
the bleed hold in the diaphragm until the pressure in compartment C rises to water line pressure. Since the area of
the diaphragm at water line pressurein compartment Cis greater than the area at water finepressure incompartment
B, the diaphragm is forced closed. The pressure at A is always lower than full line pressure because water passing
through the valve is escaping to the open air.
22
