CLOSE loop transmits operating pressure from the
The rate-of-rise circuit is designed to trip the PRP
CLOSE port of the manual control valve(s) to the
valve and actuate the sprinkler system when sufficient
operating pressure connections of the hydraulically-
heat is absorbed by the HSDs to create a definite
operated remote control valve and the hydraulically-
pressure within the circuit over a given period of time.
operated check valve.
This pressure acts against the rear of the release
diaphragm to create the pressure differential necessary
Manual Control Valve
to trip the PRP valve. Adifferential pressure of at least 8
ounces per square inch across the release diaphragm is
The manual control valve is a rotary disk plate-type
necessary to trip the PRP valve.
valve installed to permit rapid hydraulic operation of
the magazine sprinkler valve. Most systems allow
NOTE
manual sprinkler activation and securing from either a
local operating station or a remote station. This
The gauge mounted on the front of the PRP
application uses the three-way, three-position manual
valve indicates the pressure within the entire
control valve (fig. 1-8). Applications that do not
system-not the differential pressure. At times
incorporate a remote manual control station or an
the gauge may indicate a positive pressure
automatic control feature use a three-way, two-position
within the system. This is a normal condition
manual control valve.
caused by expansion of air within the system
A locking device, in the form of a key, is installed in
due to an increase in ambient temperature. The
the control valve handle to prevent accidental operation
pressure indicated on the gauge exists on both
of the sprinkler system. The locking key is secured to
sides of the PRP valve release diaphragm.
the handle with a single-strand lead-wire seal and
fastened to the valve cover by a safety chain.
HYDRAULIC CONTROL SYSTEM
The hydraulic control system operates the valves in
the dry-type magazine sprinkler system. It uses
seawater from the firemain to actuate the magazine
sprinkler control valve.
The hydraulic control system (which is better
known as the operating pressure circuit) consists of the
control system piping, a manual control valve, a
hydraulically-operated remote-control valve, spring-
loaded lift check valves, and a hydraulically-operated
check valve (normally used with the diaphragm-
operated magazine sprinkler valve) or a power-operated
check valve (normally used with the piston-operated
magazine sprinkler valve).
Operating Pressure Circuit (Control System
Piping)
The operating pressure circuit is used to open and
close the sprinkler control valves. It connects the
manual control valves, the hydraulically-operated
components of the control system, and the magazine
sprinkler valve. The operating pressure circuit is
divided into an OPEN loop and a CLOSE loop. The
OPEN loop transmits operating pressure from the
OPEN port of the manual control valve(s) to the
operating chamber of the magazine sprinkler valve and
the inlet of the hydraulically-operated check valve via
Figure 1-8.--Manual control valve.
the hydraulically-operated remote control valve. The
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