Emerson Fisher 1808 Manual

Bulletin 71.4
D100163X012
December 2019
Types 1808 and 1808A Pilot-Operated Relief
Valves or Backpressure Regulators
Figure 1. Types 1808 and 1808A Pilot-Operated Relief Valves or Backpressure Regulators
Introduction
The Type 1808 globe-style and the Type 1808A angle-style,
pilot-operated relief valves or backpressure regulators are
economical, compact devices used in gas or liquid service to
maintain pressure on oil and gas separators and in pressure
relief applications in gas distribution systems. These units
control pressures from 3 to 125 psig / 0.21 to 8.6 bar and the
set pressure is varied to individual requirements by the adjusting
screw on the pilot.
Features
• Product Longevity—The measuring element
(diaphragm) is not in the direct flow path which could lead
to unwanted wear and tear from debris in the flow path.
• Simple, In-line Field Maintenance—With the removal of
just two nuts, the actuator assembly lifts away, exposing
the trim and leaving the main valve body in the pipeline.
• Minimize Field Interference Fits and Complicated
Piping—Internal pressure registration eliminates the need
to install a control line. Most mounting orientations can be
obtained due to the minimized piping interferences.
TYPE 1808 TYPE 1808A
• Simple, Reliable Design—The simple design
has fewer parts for reliable service and minimum
spare parts inventory.
• Compact and Lightweight—Less than 12 in. / 305 mm
tall and weighs 25 lbs / 11 kg or less, these units are easily
transported and installed where space is limited.
• Versatility in Both Liquid and Gas Service—Pilot exhaust
port and standard tapped pilot spring case (Figure 2)
both come with removable vent for remote piping when
necessary. The standard tapped pilot spring case comes
complete with a gasketed closing cap that permits pressure
loading for remote pneumatic adjustment of the set pressure.
• Optional Upstream Registration for Reduced
Buildup—For gas service with the Type 6358B pilot,
upstream control line construction is available to
provide wide-open relief flow capacity with less buildup
regardless of set pressure.
• Self-Draining Body—The Type 1808A angled body
design has increased capacity and provides complete
process fluid drainage from body cavity during shut-down
period or before disassembly of the main valve.
Type 1808