left side and the other on the right side). There is a
mounting bracket supplied with each vacuum valve.
Figure #9 (“Vacuum Valve Interfaces”) illustrates the
plumbing interface details. Elevation of the valve is
very critical, as is the positioning of the nozzles.
Maximum height above the water supply line the valve
should be installed is 12” (30 cm). Never install the
vacuum valve below the water feed lines.
The water flow rate through this valve is limited to
24 gph which limits the number of AFE nozzles it
supplies to 16. If more than 16 nozzles are to be
installed, then the system must be broken into zones
using multiples of 16 (or less) nozzles with each zone
controlled by its own vacuum valve. One control panel
can control multiple zones by “T”ing off the single
control panel air pilot output.
Air pressure from the control panel is used to open
the water safety valve permitting water to enter the
vacuum valve which controls the water feed to the
nozzles. Figure #8 (“Vacuum Valve Operation”)
explains the operation of this water regulator. The
vacuum valve assembly has three sub-components.
As illustrated in Figure #9 (“Vacuum Valve Interfaces”)
First, the safety valve interfaces directly with the
primary water supply with its only duty being opening
or closing on command from the control panel. Loss
of pilot air pressure below 10 psig will automatically
close this valve to prevent water proceeding beyond
this point. In series with and downstream of the safety
valve is the water regulator used as the first stage of
water pressure reduction. The water regulator
reduces the supply water pressure to a range between
5 and 10 psig. This is set manually at installation but
system performance is not sensitive to the exact
setting as long as the pressure is within this range.
The second stage of water pressure reduction is
the vacuum diaphragm which drops the pressure to
that of the room. Output is through one exit port on
each of its two sides. This permits the nozzle to draw
water from the supply as it is required rather than
having pressure force it into the nozzle. This
siphoning action of the nozzle is controlled by the pilot
operated air regulator.
On top of the vacuum valve is a thumb wheel
adjustment for adjustment of the AIRFOG droplet size.
The adjustment changes the availability of water to the
nozzles. Thus a reduction in available water for the
same air consumption results in smaller droplets and a
finer spray. This adjustment can be used to reduce
the water throughput if there is a problem with water
droplets reaching the floor.
PILOT OPERATED AIR REGULATOR
The pilot operated air regulator controls the air
feed to the nozzles and is illustrated in Figure #11
(“Pilot Air Regulator”). This pilot regulator is an analog
flow controller rather than a simple On/Off valve. The
greater the pilot air pressure, the greater the air
pressure fed to the nozzle supply network. This
means that the Control Panel is able to demand a
proportional opening of the Air Regulator simply by
varying the pilot pressure. There is a linear 1:1
relationship between the pilot pressure and the output
pressure drop. A pilot air pressure of 25 psig (172.5
kPa) will drive the air regulator to have an output of 25
psig (172.5 kPa). A pilot pressure of 50 psig will drive
the air regulator to have an output of 50 psig. The pilot
air pressure range is from 0 to 70 psig.
The four ports on the pilot operated air regulator
are the pilot air pressure input from the control panel,
the primary air supply input feed, the output air feed to
the nozzles and to gauge port used to feed pilot signal
- 8 -
Outlet Connection
Plastic 3/8" O.D.
Tube Connection
Pressure Gauge
Water Safety Valve
Pilot Inlet
Connection
1/4" O.D. Tube
Water Inlet
Connection
3/8" O.D. Tube
Wall Bracket With
1/4" Mounting Holes
Pressure Regulator
Set To 5-7 PSIG
Fine Adjustment
Knob
View from above showing Fine
Adjustment Knob and Wall Bracket
Figure #9
Vacuum Valve Interfaces
Outlet Port
Pilot Operated
Air Regulator
Pilot Line from Control Panel
Inlet Port
Figure #10
Pilot Air Regulator
