This procedure is used to verify that the Model A Preaction
Valve will remain set if the electric detection system operates
but the sprinkler system remains in its normally pressurized
condition.
3. Open the Inspector’s Test Connection but be prepared
to close it, as well as the Accelerator Control Valve (Fig.
8), if applicable, immediately after verifying the following:
a. If the system is equipped with an Accelerator, verify
that the time to Accelerator trip is essentially the
same as in previous tests, and verify that the Differ-
ential Chamber Pressure Gauge (Fig. 7) decreases
to a pressure below 20% of the water supply pres-
sure.
b. Verify that the Low Pressure Alarm Switch (Fig. 7)
and its associated alarms operate properly. The
Low Pressure Alarm Switch should operate at the
previously established pressure (refer to Installa-
tion section, Step 7).
Close the Inspector’s Test Connection, and, if applica-
ble, close the Accelerator Control Valve.
4. Close the Differential Chamber Supply Control Valve
(Fig. 7).
5. Close the System Shut-Off Valve (Fig. 1) after the sys-
tem air pressure has been restored to normal.
6. Manually restore the electric fire detection system to a
normal condition in accordance with the manufacturer’s
instructions. The Solenoid Valve will then be de-ener-
gized and returned to its normally closed position.
7. Open the Differential Chamber Supply Control Valve.
8. Open the Main Control Valve (Fig. 1) one turn beyond
the position at which water just begins to flow from the
Main Drain Valve.
9. Close the Main Drain Valve (Fig. 7).
10. Close the Air Supply Control Valve (Fig. 7).
11. Open the Dry Pilot Actuator by partially opening the Trip
Test Flow Valve (Fig. 1) to relieve air pressure at the in-
let to the Actuator. Verify that there is no leakage out the
Dry Pilot Actuator.
NOTES
During this procedure, the Dry Pilot Actuator is opened;
however, the Solenoid Valve should remain closed and the
Model A Preaction Valve Differential Chamber should remain
pressurized.
This procedure is used to verify that the Model A Preaction
Valve will remain set if the Dry Pilot Actuator operates due to
loss of system air pressure and the electric detection system
remains in a normal condition.
12. Open (energize) the Solenoid Valve by operating the re-
leasing panel, and verify the following:
a. Verify that the Model A Preaction Valve operates,
as is indicated by a discharge of water from the Trip
Test Flow Valve and the Automatic Drain Valve. The
Automatic Drain Valve may or may not close de-
pending on the amount of flow past the partially
open Main Control Valve.
b. Verify that the Waterflow Pressure Alarm Switch
(Fig. 7) and its associated alarms properly operate.
c. Verify that the Water Motor Alarm, if applicable,
properly operates.
NOTE
This procedure simulates opening of both the Dry Pilot Ac-
tuator (loss of system air pressure) and Solenoid Valve
(operation of the releasing panel) to verify automatic system
operation.
13. Reset the Model A Preaction Valve in accordance with
the Setting Procedure section.
SERVICE RECOMMENDATIONS
Drop In Water Supply Pressure Below Normal Range
NOTE
If the water supply pressure is significantly reduced be-
low the normally expected static pressure range (as
could occur in the case of a water main break or repair),
and there is a subsequent drop in the differential cham-
ber water pressure below its normal range (due, for exam-
ple, to a leak in a piping connection to or from the differ-
ential chamber or, a leak in the differential chamber
check valve caused by dirt or debris in the check valve
seal area), a preaction valve such as the Model A could
inadvertently trip, if its water supply pressure is quickly re-
stored.
A drop in the water supply pressure to below its normal
range (as in the case of an interrupted water supply condi-
tion) constitutes an emergency impairment as defined by
NFPA 25. Should this condition occur, immediately close
the main control valve and utilize the following proce-
dure to reset the system:
1. Prior to the water supply pressure being restored to the
closed main control valve, note the pressure indicated
by the differential chamber pressure gauge and,
whether the pressure is within the normally expected
range.
2. If the differential chamber pressure is below the normal
range, check for and correct any source of leakage from
the differential chamber, prior to resetting the system.
3. After the water supply pressure is restored to the main
control valve, reset the Model A Preaction Valve in ac-
cordance with the Setting Procedure section.
NOTE
For fire protection systems subject to an emergency im-
pairment caused by an interrupted water supply condi-
tion, it is recommended that consideration be given to in-
stalling a low water supply pressure switch, with the
appropriate alarm/indications, to monitor the water supply
pressure.
Leakage From Vent Fitting (23 - Fig. 6); and
Annual Inspection of Differential Valve Disc
(36 - Fig. 2)
The Differential Valve Disc is to be inspected at least an-
nually, or when leakage is present from the Neutral Cham-
ber Vent Fitting.
When removing the Differential Housing Cover to gain ac-
cess to the Differential Valve Disc, first loosen all of the
Differential Housing Bolts, and then replace the top two
Differential Housing Bolts with 6 inch long stud bolts as
shown in Figure 11. The lower two Differential Housing
Bolts and Cover can then be removed while the Differen-
tial Housing remains temporarily supported by the stud
bolts.
Remove the Differential Housing Cover (27 - Fig. 2) and
then remove the Differential Valve Plunger Assembly for
cleaning and inspection. Carefully clean the seating sur-
face on the Differential Valve Seat (30 - Fig. 2), as well as
the counterbore where the Differential Valve Plunger O-
ring (34 - Fig. 2) seats. Carefully clean and inspect the Dif-
ferential Valve Plunger O-ring and Differential Valve Seat.
Do not unnecessarily remove the grease from the Differ-
ential Valve Plunger O-ring. Verify that the O-Ring is lubri-
cated with Grease (41 - Fig. 2). Use only Dow Corning
FS3452 Flurosilicone Grease for lubricating the Differen-
tial Valve Plunger O-ring.
With reference to Figure 2, replace the Differential Valve
STAR SPRINKLER INC.
2-4.1.10
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OBSOLETE
