Fill and Purge Breathing Cycle

Posted by Experts in Nitrogen Generators and Automatic Air Vents on Nov 24, 2017 6:25:45 AM

One of the most common questions regarding our dry pipe nitrogen inerting technology is about the location of our oxygen removal vent. How can we install our vent in the riser room while others can’t? Fill and purge breathing is how!

Fill And Purge Breathing

ECS accomplishes the goal of removing oxygen from dry pipe sprinkler systems using fill and purge breathing, which is a patented pressure cycling process unique to ECS. This process is electronically controlled by the nitrogen generator and occurs automatically while the fire sprinkler system remains in service. By design, fill and purge breathing does not impact the ability of the system to respond to a fire.

The simplest way to describe the process is that we use a small pressure range (3-5 psi) to pressure cycle the system until ALL OXYGEN GAS IS REMOVED. This small pressure differential creates sufficient gas mixing within the system such that the piping network acts as a tank or pressure vessel. Each sequential fill and purge breathing cycle dilutes the concentration of oxygen further and enriches the concentration of nitrogen gas in the piping network. Through extensive testing and empirical trials, ECS concluded that the oxygen removal vent could be located anywhere on the system and achieve the same result of 98% nitrogen gas throughout the system within 14 days.

After we determined we could install the oxygen removal vent anywhere on the sprinkler system, we decided to locate it at the riser. The location offers the most convenient location to install, operate, and maintain the vent and eliminates any potential leak risk over sensitive or critical areas of the building. Further, the location of the vent on the riser increases the ease of installation by eliminating the requirement to coordinate power to the end of the system where all others must locate their vent. Also, when using a gas purity analyzer, the ECS system prevents the need to run thousands of feet of ¼” tubing from the vent at the end of the system to a common location.

All other nitrogen generator providers utilize static system nitrogen pressure that requires the vent be installed at a less convenient remote location. This method maintains a high back pressure of nitrogen gas on the sprinkler system that sweeps oxygen out as the nitrogen gas follows the path of least resistance from point of injection to the vent location missing the dead ends (branch lines) in the system. The lack of gas mixing from this method results in longer dilution times, allowing more oxygen to react with system piping and requiring much more time to achieve 98% nitrogen.


The ECS Advantage:

  • Oxygen removal vent in the riser room
  • No nitrogen storage tanks
  • No refrigerated air dryers

New call-to-action