US/AR (Ultra Sense/Ambient Reverse-Acting) ambient sensing valves can be used to turn on glycol, air, or any other cooling media in response to ambient temperature changes to protect piping and instrumentation from overheating. Controlled by a thermostatic wax motor, the US/AR valve, will open or close over a 10°F (5.5°C) differential (i.e. 35-45°F, 90-100°F, etc.) to provide an optimal operating temperature.

As ambient temperatures rise above the desired set-point, the US/AR will automatically open allowing the media through the cooling line to cool the piping exposed to hot temperatures. Once the ambient temperature drops to 10°F below the valve’s set-point it will modulate closed (Example: a 100°FF valve would open at 100°F and close off at 90°F, keeping the process fluid between 90° – 100°F).

Typical Applications

There are many uses for these compact, self-contained, automatic flow control / ambient sensing valves. The most common application is on air or glycol cooling lines to protect facility pipelines from overheating. The valves automatically control the flow of the cooling media to keep the process lines within the specified temperature range.

In heating applications, the direct-acting, US/A valve is designed to simplify winterization procedures by turning on steam, air, gas, or liquids in response to ambient temperature changes to protect piping and instrumentation from freeze damage.

Design Features

  • Exclusive self-actuating Thermoloid® blend wax thermal actuator
  • Stainless-steel body, fittings, and plugs
  • Compact, low mass – Fast response
  • Corrosion-resistant – long service life
  • Ram-type plug for tight reliable shutoff
  • Wide choice of set points available


  • Self-operating – No external power source required
  • Protects process lines from overheating
  • Unaffected by pressure variations
  • Quick and easy installation




624 - 000100 - XXX

½” US/AR

625 - 000100 - XXX

¾” US/AR


  1. Full open temperatures “XXX” available: 040°F, 045°F, 050°F, 060°F, 070°F, 075°F, 085°F, 095°F, 100°F, 105°F, 110°F, 115°F, 120°F, 125°F, 130°F, 140°F, 150°F, 160°F, 170°F, 175°F, 180°F, 190°F, 200°F, and 210°F
    1. Closing temperature is typically 10°F below the opening temperature for Reverse Acting valves


  • Sizes: ½”, ¾”
  • Maximum Operating Pressure: 200 PSIG (13.8 BAR)
  • Maximum Valve End Temperature: 388°F (198°C)
  • Maximum Sensing End Temperature: 250°F (121°C)


US/AR Valve Product Sheet
US/AR Installation and Maintenance Instructions
Instrument and Process Temperature Control Brochure