Page 27 - NG-1 1150, NG-1 1500, NG-1 2000, NG-1 3000 - Stand-Alone Nitrogen Generator System Installation Manual

Sequence of Operation
Once in service, the nitrogen generator requires no additional intervention to function properly. Generator settings should not be altered without consulting with Johnson Controls and the unit should not be powered down or bypassed for any reason other than a service or maintenance procedure as detailed in the Maintenance Section. The nitrogen generator operates in two (2) modes, Nitrogen Inerting Mode and Supervisory Gas Mode.
Nitrogen Inerting Mode
The application of supervisory nitrogen gas to a dry pipe or preaction fire sprinkler system using the TYCO Dry Pipe Nitrogen Inerting (DPNI) protocol is fundamentally different than the traditional application of compressed air as a supervisory gas. Because the DPNI protocol uses a process called “fill and purge breathing” it requires small (3-5 psig (.2-.3 bar)) supervisory pressure fluctuations in the fire sprinkler system(s) to remove oxygen before it can cause corrosion.
• The nitrogen generator and compressor will cycle on to increase the pressure in all fire sprinkler systems connected to the nitrogen generator.
• Once the high-end pressure of the breathing cycle is reached the air compressor and nitrogen generator will turn off and the fire sprinkler system(s) will depressurize gradually through the oxygen removal vent(s).
• Once the low-end pressure of the breathing cycle is reached, the air compressor and nitrogen generator automatically turn on to repeat the process.
• The high-end/turn-off pressure is determined by the pressure setting of the fire sprinkler system(s) air maintenance device (AMD) and the low-end/turn-on pressure is determined by the nitrogen generator’s integral pressure transducer.
• The air compressor and nitrogen generator are simultaneously cycling the pressure in all fire sprinkler system(s) by 3-5 psig (.2-.3 bar) during each cycle. This will result in longer run times of the air compressor and nitrogen generator than a traditional air compressor configured to supply supervisory gas.
• The DPNI “fill and purge breathing” protocol described above is performed for a fourteen (14) day period, during this time the system pressure will fluctuate between the high-end and low-end breathing pressures.
• Once the fourteen (14) day period is complete and the ball valve on the TAV-D vent is closed or the SMART vent is automatically closed, the run frequency of the air compressor and nitrogen generator is reduced.
It is important to remember that closing the vents will not affect the runtime of the air compressor and nitrogen generator. It will only affect the frequency that the air compressor and nitrogen generator will run. The nitrogen generator and air compressor are designed to run for up to two (2) hours at a time when filling all the systems with 3-5 psig (.2-.3 bar) of high purity nitrogen. If air compressor and nitrogen generator runtimes are greater than four (4) hours, contact Johnson Controls.
TFP1275 Page 26 of 84