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The system must include a supervised system control valve upstream of
the deluge valve and a supervised system isolation valve downstream of
the isolation check valve. The downstream system isolation valve is
required to facilitate maintenance of the system and isolation of antifreeze
solution during maintenance and testing. A pressure relief valve on the
antifreeze side of the primary check valve shall be pre-set to protect the
sprinklers at 175 PSI (1 207 kPa) and piped to drain. This will handle
over-pressurization due to thermal differentials in the area of the
antifreeze piping and system operation. Consideration of location height
of PRV relative to the sprinklers must be taken into account. Calculate the
differential height and specific gravity of antifreeze at the operating
temperature of the freezer and size the PRV relief pressure accordingly.
The alarm line of the deluge valve shall be attached to an alarm pressure
switch (and mechanical water motor alarm, if required) that activates an
alarm due to activation of the system. An additional supervisory pressure
switch on the primary check valve system side is required in order to
provide a low pressure alarm in the case of antifreeze pressure loss due
to sprinkler operation without a fire condition. In this case the antifreeze
supply must be manually shut off to the low-pressure riser. There is an
isolation valve located on the antifreeze inlet line of the riser primary
check valve.
5.1.11 Alarm Test Connection
An alarm test connection is provided on the
deluge valve trim. When testing the alarm, the
downstream isolation valve and antifreeze
isolation valve must be shut before opening the
test valve.
This is a precaution in case the deluge valve
would inadvertently operate due to problems in
the trim components and cause water to enter the
system causing possible contamination of
antifreeze. After testing of the alarm, restore the
control valves to their normal operating position
and open the antifreeze supply valve.
5.1.12 Flow Test Valve (also known as Main Drain Valve)
Annual flow tests are required for
every sprinkler system. When
performing annual water flow tests
for the Pre-Primed Single Interlocked
Preaction Cold Storage System, you
will utilize the main drain of the
isolation check valve. This will allow
the primary check valve clapper to
open also. First, close the supervised
system isolation valve downstream of
the isolation check valve. Close the
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