Inlet seal does not fully close.
(a) Test procedures for early design pre-regulators are (with the
adjusting screw, spring, and piston still removed) to apply pressure at the inlet and
verify that there is no air leakage from the pre-regulator.
(b) Test procedures for current design pre-regulators are to install a
new pre-regulator and re-test the unit.
If there is no leakage, clean and lubricate all parts and reassemble.
Re-test the unit.
(d) If there is any leakage, clean and inspect the inlet seal area. If any
parts are defective, replace the pre-regulator with one of the new design. Re-test the
b. No Pressure from the Outlet. A possible cause for this is that the pre-
regulator is improperly adjusted. The test procedure is to try adjusting the pre-regulator
by turning the knob clockwise.
If this results in pressure at the outlet, adjust the pressure.
(a) Turn the knob clockwise to increase pressure.
(b) Turn the knob counterclockwise to decrease pressure.
When adjusting to decrease pressure, you must relieve the pressure in the
system before reading the gauge because the pilot-operated regulators are
not self-relieving. Do this by running a handpiece or depressing the syringe
(2) If adjustment does not result in pressure at the outlet, check for air
pressure at the supply.