F-1031, Section 2119
Page 22 of 24
Fixed Air Regulator Function
The fixed air regulator has two primary functions in the
control air circuit:
1. When the Auto-Sync is in the
“Fixed”
mode, the
fixed air
regulator controls the air circuit’s regula-
tion.
2. When the Auto-Sync is in the
“Auto”
mode, the
fixed air regulator acts as a governor or maximum
pressure limiter for the air circuit
How does the fixed air regulator work?
The fixed air regulator has 5 elements that work together
to provide regulation: inlet, outlet, disk, spring and adjust-
ment screw, Air enters the regulator through the inlet and
applies pressure to the disk. On the backside of the disk
are the spring and tension adjustment screw (the screw is
used to give the spring more or less tension). The spring
applies pressure to the disk and opposes the air pressure.
As long as the spring tension is greater than the air pres-
sure on the disk, the regulator stays closed and no air
passes through (see Fixed Air Regulator - Closed). When
the air pressure rises and becomes great enough to over-
come the spring, the disk moves allowing air to pass on
through the outlet (see Fixed Air Regulator - Open). De-
pending on how the adjustment screw is set, the spring
will apply a force on the disk in which the air pressure will
try to overcome and if the air pressure is high enough, air
passes on through.
How does the fixed air regulator operate in the air
control circuit when in the “FIXED” or “AUTO”
modes?
Fixed Mode:
The regulator basically operates as de-
scribed above. If the compressor discharge pressure is
above the fixed air regulator set point (150 psi / 10.3 bar),
then the fixed air regulator opens allowing the control air
pressure to close the air inlet valve. This will lower the
control air pressure below 150 psi (10.3 bar). When dis-
charge air pressure is below the set point (150 psi / 10.3
bar), then the fixed air regulator closes. Now the control
air pressure is not high enough to keep the air inlet valve
closed. The air inlet valve opens allowing air into the com-
pressor raising the control air pressure above 150 psi
(10.3 bar).
The fixed air regulator opens or closes as the discharge
air pressure changes to maintain the desired fixed air
pressure.
Auto Mode:
The fixed air regulator functions as a gover-
nor (or maximum pressure limiter). The fixed air regulator
is basically in parallel with the piloted balance valve. Alt-
hough the piloted balance valve is the primary regulator in
this operating mode, the fixed air regulator is in the back-
ground monitoring the discharge air pressure. If that dis-
charge air pressure exceeds the fixed air regulator set
point (150 psi / 10.3 bar), the fixed air regulator will open
allowing control air to pass onto to the air inlet valve (and
closing it). This insures the compressor cannot run at
pressures high than that set by the fixed air regulator.
Fixed Air Regulator - Open
Fixed Air Regulator - Closed
Spring & Ad
justment
Screw
Disc
Outlet
Inlet
Outlet
Inlet
