Page 181 - Valve Selection Handbook

168 Valve Selection Handbook

The following describes a typical range of direct-loaded pressure relief
valves as offered by the industry.
Safety Valves

Safety valves, such as those shown in Figure 5-3 through Figure 5-6,
are intended primarily for the relief of steam in industrial boiler plants
and other steam systems. Their design is directed towards protecting the
spring from excessive temperature rises that might cause drift of the
spring setting and possibly spring relaxation over time. To provide this
protection, safety valves are commonly provided with an open bonnet
that allows steam leaking into the bonnet to escape directly into the
atmosphere around the valve.

Figure 5-3. Safety Valve. Figure 5-4. Safety Valve With
(Courtesy of Dresser Industries.) Cooling Spool. (Courtesy of
Crosby Valve & Gage Company,
Wrentham, MA.)