(8) Releasing the signal air pressure allows the spring to push the stem and
diaphragm back up to close the valve.
c. Foot Control. The foot control is actuated by foot pressure on the cover,
which depresses the stem assembly in the valve bore. This moves the fluted surfaces
of the stem below the inlet O-ring seal, allowing air to flow to the outlet. When foot
pressure is released, the stem returns, sealing the inlet at the O-ring. Any pressure
from the outlet side of the valve is then exhausted as the fluted surfaces move above
the outlet O-ring seal. Refer to figure 4-4.
Figure 4-4. Foot control.
UNIT OPERATION AND CHECK OUT PROCEDURE
Prior to operating the dental operating unit, perform the following check out
a. Turn the dental operating unit ON.
Turn the alternating current (ac) power ON.
Turn the air closet valve ON.
Turn the water closet valve ON.
Turn the vacuum system ON.
b. Verify that there are adequate delivery pressures in the dental unit. Check
the filters monthly to ensure there are adequate delivery pressures in the dental unit. If
necessary, clean the filters at the air and the water utility module. The optimum system
pressures for all A-DEC units are as follows.
80 pounds per square inch (psi) for air.
40psi for water.