Sprinkler Devices

Air Release for Wet Sprinkler SystemsAR-1 with FM Logo

The FM Approved UNITED Fire Systems Model AR-1 Fire Sprinkler System Air Release is a device for releasing the trapped air from the high point of a wet sprinkler system.

Trapped air in a wet sprinkler system significantly increases internal corrosion by greatly increasing the dissolved oxygen levels in the water. Concentration levels of dissolved oxygen in the trapped air can be as high as 40 PPM. Corrosion rates respond linearly to the dissolved oxygen level.

Typical problems caused by this oxygen are the formation of tubercles and corrosion deposits. If not corrected, trapped air can lead to pipe blockages, leaks, and pipe failure.

Using an FM Approved UNITED Fire Systems AR-1 air vent at the system high point allows oxygen rich air to vent from system.

Air in the system migrates to the vent. The vent automatically closes when water reaches the vent. Water leakage from the unit’s outlet should be minimal. If desired, installer-supplied polyethylene tubing may be attached to the outlet using the supplied elbow and push-to-connect tubing fitting.


  1. Unit is factory assembled – do not disassemble.
  2. Unit must be mounted upright as shown.
  3. Inlet union may be used to facilitate installation and properly position unit.


The 2016 edition of NFPA 13, Standard for the Installation of Sprinkler Systems, requires a method to vent trapped air in all new wet pipe sprinkler systems. The language of this requirement is:

7.1.5 Air Venting. A single air vent with a connection conforming to 8.16.6 shall be provided on each wet pipe system utilizing metallic pipe. Venting from multiple points on each system shall not be required.

8.16.6 Air Venting. The vent required by 7.1.5 shall be located near a high point in the system to allow air to be removed from that portion of the system using one of the following methods:

  1. Manual valve minimum 1/2” size
  2. Automatic air valve
  3. Other approved means.

Data Sheet

Data Sheet – UFS-700 Rev 1.04 Air Release Model AR-1UFS-700

Instruction Sheet

UFS-701 Rev 1.03 Instruction Sheet – UFS AR-1 Air Release PN 31-100013-001UFS-701

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