sprinklernotes
Water Delivery Times for Dry-systems
You asked the following questions: “In performing the timed water delivery test
for dry systems, are you required to have a constant and steady stream of water
discharging through the inspectors test connection to pass the test?” In
response to your question, we have reviewed NFPA 13, 2016 edition as the
applicable standard. Our informal interpretation is water is just needed to
initially discharge from the test connection outlet.
It is nearly impossible to meet a water delivery time requirement for dry pipe
sprinkler systems if you have to discharge a constant stream of water to the
test connection and purge all of the air from the system in a timely manner.
The annex section of A.25.2.3.2.3 tells us the test criteria is based on the
first evidence of waterflow to the inspector’s test and air can be mixed with
water for several minutes until the air is completely purged from the system.
Additionally, in the 2016 NFPA 13 Handbook there is a FAQ on page 1091
discussing this very topic titled, what is meant by “first evidence of
waterflow” and the answer is as follows. “The measurement of the time for water
to be discharged from the inspector’s test connection is based on the first
evidence of waterflow, because it would be subject to interpretation if waiting
was required to determine when a steady flow rate was achieved. During testing,
the water discharging from the inspector’s test connection will initially be
erratic, with spurting and momentary stoppages, due to mixing with air that is
still in the system.” One thing to keep in mind, if it were a real fire event
and more than one sprinkler activated the air would be purged from the system
at a faster rate that it would from just a single outlet.
