Technical data
33.
2.5.2 Model EPS10 Pressure Switch
The System Sensor Model EPS10 pressure switch is used for single interlock preaction systems and
Reliable Type D Double Interlock Preaction Systems using pneumatic pressures between 7 psi (0.48)
and 10 PSI (0.7 bar). The EPS10-1 Series (one SPDT switch) and EPS10-2 (two SPDT switches) feature
field adjustable pressure sensitivity between 4 and 20 psi (0.3 and 1.4 bar) and are used for low pres-
sure supervision. For Type D Double Interlock Preaction Systems, the EPS10 is also used for system
activation when cross-zoned with the supplemental detection system. Switch transfer occurs upon the
loss of approximately 3 psi (0.21 bar). Although factory set, the adjustment wheel requires no special
tools and can be used to adjust the nominal value of the “window” at which the switches activate.
2.6 Quick-Opening Device
NFPA 13 requires that water be delivered to the inspector’s test within 60 seconds of valve operation on
double interlock preaction systems over 500 gallons and on dry pipe systems over 750 gallons. A quick-
opening device or accelerator can be installed on the system to help achieve the water delivery time. Dry
pipe systems that do not exceed 500 gallons capacity are not required to meet a specific water delivery time
when provided with a quick-opening device.
2.6.1 Model B-1 Accelerator with Trim for Model DDX Deluge Valve
The Reliable Model B-1 Accelerator is a normally-closed valve that is highly sensitive to the rate of
pneumatic pressure change in the system. The top chamber is filled to normal pressure with system air
or nitrogen, and is designed to accommodate minor fluctuations in pressure. The device retains normal
pressure in the top chamber when pressure drops as a di-
rect result of one or more sprinklers opening. Upon this sig-
nificant pressure decay, the top chamber exerts a downward
force across the diaphragm assembly, forcing the valve to
open and allowing system pressure to discharge to atmo-
sphere. Operation of the accelerator speeds up the purging
of pressure from the pneumatic side of the LP Actuator and
opening of the Model DDX Deluge Valve. Simultaneously,
pressure passes through the accelerator and closes the in-
tegral Accelo-Check preventing water and water-borne de-
bris from entering the device. This increases reliability of the
accelerator and reduces maintenance that otherwise would
be required after each operation.
Approvals and technical data for the Reliable Model B-1
Accelerator can be found on Reliable Automatic Sprinkler
Company Bulletin 323. Additional information can be also
found on bulletins for those systems that can benefit from the
addition of a quick-opening device.
2.7 Alarm Devices
An essential element of any automatic fire protection system is the ability to provide audible and visual no-
tification upon detection of a fire and/or release of the system. This section is intended to provide the user
with the most common types of alarm devices; it is not intended to convey all the requirements of NFPA 72 or
other applicable codes. Responsibility for the actual design of any fire alarm system rests with the engineer
of record, certified layout technician, and/or the Authority Having Jurisdiction.
2.7.1 Model C Mechanical Alarm
The Model C Mechanical Alarm, also called a water mo-
tor gong, is a hydro-mechanical alarm usually mounted on
an outside building wall and energized by water flowing
through a primary system control valve. When the system
control valve is operated, water flows from special porting
through the ¾” strainer and ¾” piping that connects to the
water motor alarm. In the motor, water passes through a
nozzle directed against the Pelton wheel blades causing the
Pelton wheel to rotate. The striker assembly is connected
to the Pelton wheel by a drive shaft that also rotates caus-
ing the striker to impact against the gong, producing a con-
tinuous piercing alarm. After impinging against the Pelton
wheel the water drains through an outlet in the motor body.
Figure 38
B-1 ACCELERATOR
WITH DDX TRIM
Figure 39