Design Criteria
In planning the installation, considera-
tion must be given to the disposal of
the large quantities of water that may
beassociatedwith drainingthesystem
or performing a flow test.
Valves installed in the vertical position
must have the flow going up. Valves
installedinthehorizontalpositionmust
bepositionedso thatthe drainconnec-
tion points down.
Thesprinklersystemdesignermustbe
aware that the configuration of the pip-
ing network and its tendency to trap
pockets of air (such as in the case of a
peaked-roof gridded system) can af-
fect the performance of the alarm sys-
tem. Although a slight amount of
trapped air is desirable to prevent sig-
nificant pressure increases due to
thermally induced expansion of the
water, a large quantity oftrapped air in
a system may result in the possibility
of an intermittent alarm.
The possibility of an intermittent alarm
condition is a consequence of the fact
that the flow out of the system through
the test valve or a single sprinkler is
very small relative to the flow that can
be passed through the valve. This dif-
ference increases with valve size. If
the system were free of trapped air,
flow in would equal flow out and the
Clapper would always stabilize at
some open position (as needed to ac-
commodate the required flow). With
trappedairinthe system,however,the
Clapper first opens wider since the
system initially demands greater flow
until the air pockets are compressed
(back to nearly the supply pressure),
and then it will tend to return closer to
the Seat Ring. If the volume of the air
pockets is excessive, flow into the sys-
tem can be momentarily reduced to
nearly zero (once the air pockets are
compressed) and the Clapper may
close, causing flow to the alarms to be
shutoff.
Once the Clapper has closed, suffi-
cient water must flowout of the system
before the Clapper will again open. A
repetition of the above described con-
dition is termed an intermittent alarm.
Using a vent (which can also serve as
an end-of-line Inspector’s Test Con-
nection) piped from the top of a cross
main or end of a branch line at the
point most remote from the alarm
valve, and filling the system slowly in
accordance with the steps described
in the Setting Procedure section, can
prevent an excessive amount of air
from being trapped.
Installation
NOTES
Proper operation of the Model AV-1-
300 Alarm Check Valves depends
upon the trim described in this data
sheet being installed in accordance
with the following instructions. Failure
to follow the appropriate trim installa-
tion instructions may prevent the de-
vice from functioning properly as well
as void listings/approvals, and the
manufacturer’s warranties.
The Alarm Check Valves must be in-
stalledinreadilyvisible andaccessible
locations.
It is recommended that provision be
made for viewing the alarm line drain
water by locating the main drain outlet
in a readily visible area.
Wet pipe fire protection systems must
be maintained at a minimum tempera-
ture of 40°F/4°C.
Step 1. Trim the Alarm Check Valve in
accordance with Figure 4, 5, or 6, as
applicable. Apply pipe thread sealant
sparingly to male threads only.
Step 2. The Alarm Vent Trim illus-
trated in Figure 8 must be installed if a
water motor alarm is not to be used.
Step 3. Plug unused alarm connec-
tions.
Step 4. Suitable provision must be
made for disposal of alarm line and
system drainage water. Drainage
water must be directed so that it will
not cause damage or result in danger-
ous conditions.
Step 5. The alarm line drain must be
arranged so that there will be no dan-
ger of freezing.
Step 6. The check valve in the exter-
nally mounted bypass around the wa-
terway Clapper must be installed with
its arrow pointed up, and the drain
check valve must be installed with its
arrow pointing towards the drain.
Step 7. It is recommended that a vent
connection (which may also be used
as an end-of-line Inspector’s Test
Connection), be piped from a cross
main or branch line at the point most
remote from the alarm valve. The vent
line should be connected to the top of
a cross main or to the end of a branch
line and be located at the highestlevel
of a multi-level installation.
The vent connection can be used to
bleedoff excessive air from the sys-
tem, and therefore, minimize the pos-
sibility of a false alarm due to a tran-
sient surge in supply pressure. The
contraction/expansion associated with
an excessive amount of trapped air
could also cause the waterway Clap-
per to cycle open and shut during an
inspector’s test or during a discharge
by a single sprinkler.
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