TRAC Style ‘A’
The TRAC Style ‘A’ (Failsafe) temperature regulator is a self-sensing and self-actuated temperature regulating valve that automatically controls liquid or steam flow in response to temperature changes in the controlling medium. The regulating valve requires no external power source to operate or to detect temperature changes in the controlling medium. The TRAC Style ‘A’ is suitable for shipboard service.
Failsafe is a term invoked by the military specification to differentiate this type of equipment from the standard (non-failsafe) design. It describes the failure mode that the system designer must consider as safest for the system. For most applications where the TRAC Style ‘A’ (Failsafe) temperature regulator is specified, the valve is intended to fail cold. The failsafe temperature regulator will fail in the full open or full closed position (depending on valve action) with no means to adjust the valve to an intermediate position. If adjustment to an intermediate position after thermostatic element failure is a system requirement, then consider the TRAC Style ‘B’ temperature regulator.
The TRAC Style ‘A’ Temperature Regulator is available in three types of valve action:
DIRECT ACTING: Direct acting valves are used for heating services where a rise in temperature tends to close the valve. A direct acting valve is generally used for controlling the temperature of any steam-heated systems such as hot water tanks, steam tables and sterilizing equipment.
Body and trim categories: single seat (cone disc), balanced single seat, double seat direct acting – union end or flanged end connections, and double seat reverse acting – union end or flanged end connections
Fails closed (in a heating system, the valve fails cold)
Applicable specification: MIL-V-19772A / MIL-DTL-19772B TYPE II CLASS 1 (Failsafe)*
REVERSE ACTING: Reverse acting valves are used for cooling services where a rise in temperature tends to open the valve. A reverse acting valve is generally used for controlling the temperature of cooling system recirculating lines, heat exchangers, environmental air cooling, etc.
Body and trim category: double seat reverse acting – union end or flanged end connections
Fails open (in a cooling system, the valve fails cold)
Applicable specification: MIL-V-19772A / MIL-DTL-19772B TYPE II CLASS 2 (Failsafe)*
THREE-WAY: Three-way valves are used for mixing hot and cold liquids to deliver liquid to the outlet at a predetermined temperature, or to divert the inlet flow of liquid to a heat exchanger or bypass based on the controlling condition.
Available with either union end or flanged end connections
Three-way valves for mixing service fail cold (hot seat shut)
Three-way valves for diverting service will fail to cooler (bypass seat shut)
Applicable specification: MIL-V-19772A / MIL-DTL-19772B TYPE I (Failsafe)*
*The military specification type and class generally associated with each type of valve action is included with each valve description. Departures from the military specification valve are available. These modifications include, but are not limited to, changes in body material, trim material, end connections and rated pressure.