Three-way valve
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A three-way temperature-control valve has been added to the range of valves produced by Spirax-Sarco. It is known as the Sarco TW and is designed for low-pressure hot-water systems; it can, for example, be used to
process hot-water supplies and the cooling systems of diesels and compressors, including brine systems. Hydraulically operated and having packless glands, it is available in sizes of }in. to 3in. dia. With the exception of the 3in. size, the valves are operated by standard thermostats; because of its greater valve travel, the 3in. valve requires a modified thermostat system.
The lin. and 4in. valves have gunmetal bodies with either screwed or flanged connections, while 2in. and 3in. sizes have cast-iron or gunmetal bodies with flanged connections. Based on the Sarco Type 58 diesel diversion valves, the working unit in the TW range consists of a gunmetal piston sliding in a PTFE-sleeved silicon-rubber 0-ring. The piston seats on a machined face at each end of its travel.
Maximum body pressure and temperature limits are 275 psi (19 bar) 250deg F (120deg C) respectively for the gunmetal valves and 150 psi (10.5 bar) 250deg F (120deg C) for the cast-iron units. Maximum differential pressures are 50 psi (3.4 bar) for the lin., 1 in. and 14in. sizes and 40 psi (2.7 bar) for the 2in. and 3in. sizes. The valves can be used on both heating and cooling applications within their pressure and temperature limits.
Made by: Spirax-Sarco Ltd, Charlton House, Cheltenham, Glos.