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How Many Inerting Vents (PAV-WN) Do I Need Per Fire Sprinkler System?

You'll need a single PAV-WN vent, a nitrogen injection port, and a source of nitrogen.

When performing Wet Pipe Nitrogen Inerting (WPNI) on a wet fire sprinkler system there are three (3) required system components:

  • A single PAV-WN inerting vent installed at a remote high point on the system. The PAV-WN has been specially designed to work with the WPNI process. It is equipped with a nitrogen retention device to automatically retain nitrogen during the inerting process. By retaining the nitrogen gas during the purging process, cycle times are quicker, and the amount of nitrogen gas required is less. The PAV-WN is also equipped with a gas sample port that can be used to verify proper nitrogen purity levels are being achieved. Once the WPNI process has been performed the PAV-WN vent will release trapped nitrogen gas as the system is filled with water.
  • A Nitrogen Injection Port installed at the riser above the alarm check valve or control valve for the zone. The nitrogen injection port is designed to allow the temporary connection of a nitrogen source to the fire sprinkler system when performing the WPNI process.
  • A source of nitrogen. Typically, the source of nitrogen for the WPNI process is cylinders that are delivered to the site. In instances where nitrogen is available on-site, or the WPNI project is large enough, a nitrogen generator can be used as the source of nitrogen.