TFP910
Page 18 of 20
Step 8.
Using a light, check for and
remove any debris that may have
become lodged within the Seat Ring
groove. Inspect the Seat Ring seat
for any damage. If the Seat Ring has
become dented across the seat then
the Alarm Check Valve will have to be
replaced. It is impractical to re-face a
Seat Ring in the field.
Step 9.
Check for and remove any
debris that may have become lodged
in the Clapper Facing. If a minor imper-
fection remains in the Clapper Facing,
then turn it over after thoroughly clean-
ing both surfaces with a clean cloth.
Replace the Clapper Facing if neces-
sary. Be sure to securely re-tighten
the retaining fastener for the Clapper
Washer.
Step 10.
Replace the Spring and
Waterway Clapper Assembly as shown
in Figure 1. While holding the coils of
the Spring down, re-insert the Hinge
Pin. Be sure that the Hinge Pin is
pushed all the way to the rear of the
valve.
Step 11.
Replace the Handhole Cover.
Return the Alarm Valve to operation in
accordance with the steps described in
the Setting Procedure section.
Clogged Alarm Line Drain
If water either does not flow or only
dribbles out of the alarm line drain dur-
ing an alarm test, then it is likely that
the screen protecting the Restriction
Assembly drain orifice (Ref. Figure 3)
has become clogged.
NOTICE
For variable pressure systems, a
clogged alarm line drain will increase
the likelihood of a false alarm.
First break the union downstream of
the Drain Restriction and remove the
Drain Restriction for cleaning by back-
flushing the screen. Re-install the Drain
Restriction and re-assemble the drain
line.
Loss of Excess System Pressure
For variable pressure systems, the
System Pressure Gauge normally indi-
cates a pressure greater than that
shown by the Supply Pressure Gauge.
Also, the value should be close to that
of the peak supply pressure that has
occurred after the system was placed
in service.
NOTICE
For variable pressure systems, loss of
excess system pressure will increase
the likelihood of a false alarm.
Follow the procedure indicated below
to correct a loss of excess system
pressure condition.
Step 1.
Check for signs of continued
leakage from the alarm line drain. If rust
stains and/or water deposits indicate
that continued leakage has been taking
place, take corrective action according
to the procedure described in the sub-
section entitled “Leakage from Alarm
Line Drain.”
Step 2.
If there are no signs of contin-
ued leakage from the alarm line drain,
close the main control valve, slowly
remove the plug from the supply pres-
sure gauge test valve to relieve the
supply pressure, and then slowly open
the union in the externally mounted
bypass.
Step 3.
Check for leakage past the
Bypass Check Valve. If there is leak-
age, debris may have become lodged
between its clapper and seat. Drain
the system in accordance with the
prescribed procedure and then clean
or replace the Bypass Check Valve as
required.
Step 4.
Re-assemble the externally
mounted bypass, replace the plug into
the Gauge Test Valve, and return the
fire protection system to operation in
accordance with the steps described
in the Operation section.
Step 5.
If there are no signs of leak-
age past either the Alarm Check Valve
Clapper per Step 1 or the Bypass
Check Valve per Step 2, inspect the
sprinkler system for leakage.
Excess Pressure Due to
Thermal Expansion
Wet pipe sprinkler systems subject
to ambient temperatures in excess of
100°F (38°C) can experience significant
increases in system pressure due to
the thermal expansion of the water. In
particular, a gridded wet-pipe system
with a relatively small air pocket and
no relief valve can be subjected to an
increase of more than 100 psi (6,9 bar),
due to an increase in ambient tempera-
ture of approximately 50°F (28°C).
As necessary, install a pressure
relief valve, in accordance with the
requirements of the authority having
jurisdiction, to automatically relieve
the excess pressure that could other-
wise be created in wet-pipe systems
exposed to significant increases in
ambient temperature.
False Alarms
Follow the step below when repeated
false alarms occur in a variable pres-
sure system.
Step 1.
Check for and correct the
cause of continued leakage out the
alarm line drain.
Step 2.
Check for and clean a clogged
alarm line drain.
Step 3.
Check for and correct the
cause of a loss in excess system
pressure.
Step 4.
Drain the sprinkler system and
re-fill it using the steps described in the
Setting Procedure section.
Intermittent Alarms
If the pressure alarm switch gives a
steady signal, but the water motor gen-
erates an intermittent alarm, check for
binding in the water motor alarm drive
shaft.
If the water motor alarm and/or the
pressure alarm switch provide an
intermittent alarm, it is likely the conse-
quence of an excessive amount of air
being trapped within the sprinkler sys-
tem. Drain down the sprinkler system
and refill it using the steps described in
the Setting Procedure section.
A discontinuance of an alarm may also
be caused by the Clapper closing due
to a sudden drop in supply pressure
or the shut-off of a pump in the supply
line. These types of problems can only
be corrected by maintaining a steady
supply pressure.
