Design D t
An Air Maintenance Device should be permanently
connected to all dry pipe sprinkler systems to avoid the
possibility of false valve “trips” which may result from
small piping leaks gradually lowering system air
pressure.
An Air Maintenance Device may also be utilized to
automatically control the air supply to the piping system
of an air supervised preaction system or to the pilot lines
of a dry pilot actuated deluge valve.
There are several methods of providing a constant and
controlled supply of air to a sprinkler system as follows:
Air Compressor nd Air M inten nce Device Model
(AMD-2)
The air compressor is connected electrically and
mechanically to the trim of the dry pipe valve, through an
Air Maintenance Device equipped with a pressure switch.
The air pressure switch continuously senses the air
pressure in the piping system and turns the compressor
on if the pressure drops below the cut-in setting and turns
the compressor off if the pressure rises above the cut-out
setting. The cut-in pressure is usually set at the design
air pressure for maintaining the dry pipe valve in the
closed position. The cut-out pressure should be set
approximately 10 psi above the cut-in pressure.
Note: If the dry pipe valve is equipped with an
accelerator, this method of air maintenance is not
recommended. The accelerator is sensitive to a 3 to 5 psi
air pressure drop at a rate of approximately 1 psi in 10
seconds - see AMD-1.
Air Compressor with Air Receiver T nk nd Air
M inten nce Device (Model AMD-1)
The compressor-tank unit is equipped with an integral
pressure switch that controls the pressure in the tank,
maintaining the tank pressure at a level 10 to 15 psi
above the designed air pressure demand of any dry pipe
system supplied by the air compressor tank unit. The
compressor-tank unit is mechanically connected to the
trim of the dry pipe valve, through an Air Maintenance
Device equipped with an air pressure regulator. The
pressure regulator continuously regulates the incoming
air (from the air receiver tank) and maintains the outgoing
air pressure at the pressure setting of the regulator,
usually within an accuracy of 1 psi. The outgoing air
pressure setting is field adjustable from 5 to 75 psi. If the
dry pipe valve is equipped with an accelerator, this
method of air-maintenance is recommended.
AMD-1 Includes Non-Listed Pressure G uge
The AMD-1 includes a non-listed pressure guage for use
with the regulator. Gauge ships uninstalled. To install,
remove the 1/8” plug on the regulator and install the
pressure gauge into the open port.
Pl nt Air Supply nd Air M inten nce Device (AMD-1)
The plant air supply is mechanically connected to the trim
of the dry pipe valve through an Air Maintenance Device
equipped with an air pressure regulator. The pressure
regulator continuously regulates the incoming air and
maintains the outgoing air pressure at the pressure
setting of the regulator, usually within and accuracy of 1
psi. The outgoing air pressure setting is field adjustable
from 5 to 75 psi. The minimum pressure in the plant air
supply must be greater than the design air pressure
required by the dry pipe system since the air pressure
regulator will only regulate pressure downward.
Inst ll tion
Gener l
The Air Maintenance Device must be installed in the air
supply line leading to the dry pipe valve trim, preaction
system piping or dry pilot system piping. The air flow
through the Device must be in the direction shown by the
arrows on the units.
Note: The minimum pipe size is 1/2” diameter, although
3/4” diameter piping will provide a more rapid initial
system fill.
Note: In particularly humid environments, a manual
desiccant air dryer (P/N AD3400) should be properly
installed between the compressor and the dry pipe valve
to remove moisture from the compressed air supply.
Condensed moisture that is allowed to back up into the
compressor cylinder may cause compressor damage.
Cold room / freezer room installations must have a
pre-packaged Dry Air Pac TM which includes an AMD-1.
Consult factory for correct installation procedures.
Model AMD-1 (Pressure Regul tor) (see Fig. 1)
Step 1. Close the 1/4” ball valves (#8) and open the
bypass valve (#7) in the Air Maintenance Device and
open the air supply valve in the dry pipe valve trim.
Step 2. Open the air supply control valve from the plant
air system or air receiver tank to pressurize the system.
Step 3. When the system is pressurized, check the air
pressure gauge to verify the the pressure is at the design
pressure requirement for the system.
(Continued)
AMDMSTR.3
01/16/13
