Bulletin 71.4:98 November 2009
W6155
TYPE 98H
W6157
TYPE 98LD
W6158
TYPE 98HD W6156
TYPE 98L
Figure 1. Typical 98 Relief Valves
The 98 Series (Figure 1) is used for backpressure or relief applications in liquid, gas, air, and steam service. The Types 98L, 98H, and 98HH are directoperated and spring-loaded. The Types 98LD and 98HD use additional pressure loading to maintain relief differential pressures, backpressures or for remote setpoint adjustment. The Type 98HM is a direct-operated, spring to close regulator for backpressure or relief applications in liquid, gas, or steam service. The regulator requires no external power to operate and features a sensing line connection for sensing pressure externally from the regulator. A seal washer for the set screw can be included when applications require pressure loading of the spring case (not available on NPS 1-1/2 and 2 bodies (DN 40 and 50)).
Typical applications include backpressure on pumps, maintaining differential pressure across lubricated seals, steam header pressure, fuel and oil lines, air supply systems, pump bypass applications for API general and special purpose lube and seal oil systems, relief other process and industrial uses. Diaphragms come in stainless steel, Monel®, Hastelloy® C, or elastomers, and body is available in cast iron and steel as well as stainless steel, Hastelloy® C, and Monel®. Corrosionresistant trims are available. Diaphragm is isolated pusher post assembly provides positive guiding for improved shutoff.
Hastelloy® C is a mark owned by Haynes International, Inc. Monel® is a mark owned by Special Metals Corporation.
D100153X012
Small size allows easy installation in limited spaces.