Halton FRH combines an exhaust valve with adjustable pressure loss and a fire damper for circular ducts. FRH prevents the spread of fire and flue gases into ventilation ductwork. The release temperature of the fuse in the fire damper is +50°C or +74°C.

FRH can also be used to adjust airflow rate and  as a measurement facility.

Ravenscroft provides Halton ULA supply air and exhaust valves for  ceiling and wall installation with adjustable pressure loss.

ULAs can be installed without an installation frame directly into ductwork or a hollow-core slab. 

In supply air application the desired flow pattern is directed using an internal sector plate. The desired pressure loss and airflow rate can be adjusted in an exhaust air application, by removing the sector plate and adjusting the front panel position.

The valve throttles the exhaust airflow and attenuates the duct noise. The pressure drop is dependant on the position of the central cone. The desired exhaust airflow rate is adjusted during the balancing of the airflows in a ductwork system. After the adjustment the valve is locked at the required adjustment position.