How Does the ECS Automatic Air Vent Work?

Posted by Tim Adams on Mar 5, 2019 2:29:34 PM

Intro & Background

Since the release and adoption of the 2007 edition of NFPA 13, fire sprinkler designers and installing contractors have been permitted to install the inspector’s test connection in “any location on the fire sprinkler system downstream of the waterflow alarm."

This update to the NFPA standard provides an opportunity to locate the inspector’s test connection at the riser along the main drain, if it is installed above the flow switch. Prior to the update, inspector’s test connections had to be installed at a remote point on the system. A best practice was for the contractor to manually bleed trapped air from the sprinkler system by opening the remote test connection during filling.The NFPA 13 technical committee recognized the unintended consequence of eliminating the requirement for remotely installed inspector’s test connections and introduced an air vent requirement in the 2016 edition of NFPA 13. Section 7.1.5 requires the installation of an air vent on all wet pipe sprinkler systems that use metal pipe. Section 8.16.6 goes on to say the vent should be installed near a system high point using either a manual vent or an automatic vent.  

While the 2016 edition of NFPA 13 has not yet been widely adopted, many end users and specifying engineers see the value an automatic air vent provides and have proactively required automatic air vents on all new wet pipe sprinkler systems as part of a best practice corrosion management strategy. An automatic air vent eliminates the element of human error found common when using manual air vents by utilizing a float valve similar to what is installed on top of a fire pump to prevent cavitation.

How the PAV-W Automatic Air Vent Works

ECS PAV-W Automatic Air Vent installed on fire sprinkler pipeOur PAV-W Ejector Automatic Air Vent is a simple redundant mechanical design. Its redundant design eliminates the need for the vent to be piped to a drain, thus saving install cost. It contains a pressure gauge in line for easy inspection and maintenance that allows the end user to check for correct functionality. The simple design allows water to drain back into the sprinkler system, allowing for immediate reuse of the vent.

Upon installation and filling of the wet pipe sprinkler system, the isolation ball valve on the wet system vent should always be left open to allow migrating air to vent. When the system begins to fill, the automatic air vent will immediately begin to vent any excess air trapped in the system.

As water begins filling the system, it will eventually work its way to the vent through the outlet (welded or mechanical), passing through the Y-strainer before sealing the float chamber. The purpose of the y-strainer is to remove any debris from the water stream that could potentially harm the buoyant float device and orifice. Once the water enters the primary float, it begins to fill the chamber, simultaneously raising the buoyant float and eventually sealing the vent off.

The ECS Automatic Air Vent is equipped with a patented redundant float design, allowing the vent to be installed without being plumbed to a drain. Should a failure occur in the primary float, water will overflow into the secondary float and seal shut, preventing water from being discharged. If a failure has occurred the visible pressure gauge located in line with the floats will provide a system pressure reading that can be read from approximately 30 feet. For future use, drain and fill the wet pipe sprinkler system using standard procedures.


If you're interested in installing an ECS air vent on your fire sprinkler system, find more information on our products below. 

The PAV-W is now available for bulk-discount purchase directly from our online store!

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Tim Adams

Written by Tim Adams

Project Engineer