2.
Operation
• Model A-2 Pressure Maintenance Device
(Refer to Figure 1)
The Model A-2 Pressure Maintenance Device (PMD) is de-
signed for use where a source of compressed air (plant air
system, tank-mounted compressor with a pressure control,
etc.) or nitrogen cylinder (equipped with a regulating de-
vice) is available (refer to the section in this technical bulle-
tin titled “Installation”). The regulator in the Model A-2 PMD
reduces higher pressure air or nitrogen to a level required
by a dry pipe valve, dry pilot line, or a deluge valve based
preaction system. The Model A-2 PMD will maintain a con-
stant pressure in the system regardless of any pressure
fluctuations from the compressed air or nitrogen source.
Basic functionality of components (refer to Figure 1): The
strainer’s (Item 2) function is to prevent any foreign matter
that may be present in the air supply, from traveling to the
regulator (Item 1) and the check valve (Item 3), thereby en-
suring their normal operation. The check valve’s function is
to prevent the reverse flow of water resulting from a dry pipe
or deluge valve’s operation, from reaching the regulator.
The globe valves (Item 4) allow for the servicing (if needed)
of the strainer (Item 2) and regulator (Item 1) without having
to shut down the sprinkler system. The ball valve (Item 5)
permits the rapid restoration (quick-fill) of the required sys-
tem air pressure after service or operation. The ball valve
(Item 5) must be closed and the globe valves (Item 4) must
be open for proper automatic operation.
• Models B-1 Pressure Maintenance Device
(Refer to Figure 2)
The Model B-1 Pressure Maintenance Device (PMD) is
designed for use in conjunction with the Reliable Model A
Tankless Air Compressor in order to maintain the correct
air pressure in a dry pipe valve or dry pilot line (refer to the
section in this technical bulletin titled “Installation”). The Re-
liable Model A Tankless Air Compressor is controlled on or
off by the air pressure level present in the dry pipe valve or
dry pilot line via wiring between the compressor’s motor and
the contacts of the Model B-1 PMD’s pressure switch.
Basic functionality of components (refer to Figure 2): A drop
in the sprinkler system’s air pressure causes the contacts of
the pressure switch (Item 1) to close, thereby activating the
air compressor . When the pre-adjusted level of air pressure
is restored, the pressure switch’s contacts re-open, thereby
deactivating the air compressor. The pressure switch (Item
1) is also equipped with an unloader valve that automati-
cally bleeds off the air compressor’s outlet pressure each
time the contacts of the pressure switch open. This protects
the air compressor’s motor from overloading during start-
up. Like the Model A-2 PMD, the Model B-1 has a strainer
(Item 2) for contamination control and a check valve (Item
3) to prevent reverse water flow. The ball valve (Item 5) and
globe valves (Item 4) are also identical in configuration and
function as with the Model A-2 PMD. Likewise, the ball valve
(Item 5) must be closed and the globe valves (Item 4) must
be open for proper automatic operation
Adjustment
• Model A-2 Pressure Maintenance Device
(Refer to Figure 1)
The pressure regulator (Item 1) is factory set to maintain
a nominal system air or nitrogen pressure of 30 psi (2,1
bar). In order to change the outlet pressure, loosen the
locknut at the top of regulator and turn the adjustment
screw clockwise to increase pressure. To decrease the
pressure, turn the adjusting screw counter clockwise.
The resulting pressure can be determined at the sprinkler
system air gauge once the air flow through the device
has ceased, or at the optional gauge location. Shown on
Figure 1.
Note: The locknut of the regulator (Item 1) must be tight-
ened after adjusting in order to prevent an accidental
change in the pressure setting.
Adjustable Outlet Pressure Range:
5 psi to 100 psi (0.34 bar to 6.9 bar)
Maximum Inlet Pressure: 175 psi (12 bar)
• Model B-1 Pressure Maintenance Device
The pressure switch (Item 1) is factory set to maintain a
nominal system air pressure of 35 psi (2,4 bar). In order
to change the setting, remove the pressure switch’s cov-
er and follow the directions contained within the switch.
Electrical Rating:
Single Phase: 120 Volts AC; 2 hp
240 Volts AC; 3 hp
600 Volts AC; 5 hp
Three Phase: 240 Volts AC; 5 hp
600 Volts AC; 5 hp
115-230 Volts DC; 3 hp
Adjustable Outlet Pressure Range:
14 psi - to - 60 psi (1,0 bar - to - 4,1 bar)
Maximum Inlet Pressure: 175 psi (12 bar)
Listings and Approvals
1. Listed by Underwriters Laboratories, Inc. (UL)
2. Listed by Underwriters’ Laboratories of Canada. (ULC)
3. Certified by FM Approvals.
4. NYC MEA 258-93-E.
