65
NOTES:
1. Exacerbated by a small or short nitrogen supply line between the nitrogen generator and sprinkler
system.
2. Nitrogen Generator Short Cycling Prevention Device (AG-18500 and AG-22500 only) regulator
should be fully closed unless used.
3. Nitrogen Generator Short Cycling Prevention Device (AG-18500 and AG-22500 only) is typically
not needed in most applications. Adjust as necessary, when needed.
Procedure:
1. Increase set point of AMD to prevent premature shut-off of AMD regulator.
2. If set point modifications do not prevent short-cycling, repair (clean out) or replace the erratically
operating AMD.
Procedure Option for AG-18500 and AG-22500 Only
If AMD repair/replacement unsuccessful, the AG-18500 and AG-22500 nitrogen generators include a short
cycling prevention assembly. The short cycling prevention assembly allows a controlled leak after the
sprinkler system’s AMD closes to reduce the pressurizing of the supply line to the cut-out pressure of the
nitrogen generator which reduces the potential of the nitrogen generator short cycling.
1. If needed, the short cycle prevention regulator is to be adjusted to open at 10 psig (.7 bar) above
the sprinkler system operating /AMD set pressure.
a. Normal Operation: Regulator should be closed completely
b. Short Cycle Prevention: Adjust regulator to open 10 psig (.7 bar) above the sprinkler system
operating /AMD set pressure.
1) Turn regulator clockwise to increase pressure.
2) Turn regulator counterclockwise to decrease pressure.
NOTE: The short cycle prevention assembly is not a substitute for repairing an erratically operating AMD.
The short cycle prevention assembly reduces short cycling of the nitrogen generator by increasing
the time to pressurize the nitrogen supply line.
AIR MAINTENANCE DEVICE PRESSURE ADJUSTMENT PROCEDURE
The sprinkler system air maintenance device (AMD) operating pressures are determined by the sprinkler
system valve, system water pressure and water delivery time requirements as defined by NFPA 13. The
AMD operating pressures should not need to be readjusted unless one of the above fire sprinkler system
parameters change.
The following procedure has been developed to compensate for:
1. Tolerances of the gauges used on fire sprinkler systems
2. Inlet pressure fluctuations to the AMD resulting in pressure fluctuations of the AMD.
3. Interaction between AMDs when multiple sprinkler systems are connected to a single nitrogen
generator.
NOTES:
1. When the nitrogen generator is connected to multiple dry pipe and preaction systems, the
fire sprinkler systems must operate at the same supervisory gas pressure.
2. Any changes to the AMD pressure settings must be correlated with the nitrogen generator
cut-in (turn-on) and cut-out (turn-off) pressure settings, and be authorized by and under
the direction of ECS.
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