American Fire Sprinkler Association
12750 Merit Dr., Suite 350 * Dallas TX 75251
Ph: (214) 349-5965 Fax: (214) 276-0908
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TECHNICAL UPDATE
DECEMBER 6, 2007
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"WHEN HYDROSTATICALLY TESTING NEW UNDERGROUND PIPING CAN THE PRESSURE
DROP BELOW 200 PSI? OUR TEST DROPPED TO 192 PSI BEFORE PUMPING IT
BACK UP TO 200 PSI IN ORDER TO DEFINE THE AMOUNT OF LEAKAGE."
We have reviewed NFPA 13, 2002 edition that you identified as the
applicable standard. Our informal interpretation is that the test can
drop below 200 psi.
The confusion on the issue is probably stemming from the standard
being a little casual in their description of the test in
10.10.2.2.1. In this section it says "shall maintain the pressure
without loss for 2 hrs". I believe the committee, in an effort to
better coordinate the text with that for above pipe, inadvertently
included the above text. I say this since it is physically impossible
to apply the allowed leakage in 10.10.2.2.4 without a minor loss in
pressure. Underground pipe has slip-on joints as well as other
components such as valves that allow leakage. Although also worded a
bit odd, 10.10.2.2.4 (4) tells us that in evaluating the amount of
leakage we must use a calibrated container to determine the volume of
water and that we must pump the pressure back up to the specified
amount in order to complete the test. For instance, if your test
started at 220 psi due to a higher operating pressure, you couldn't
pump the system back to 200 psi when determining the amount of leakage.
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Technical Update is prepared by the Technical Services Dept. of the
AFSA: Vice President of Engineering and Technical Services Roland
Huggins, a PE registered in fire protection engineering; Phill Brown,
a NICET IV certified automatic sprinkler technician and NFPA Certified
Fire Protection Specialist (CFPS) and Tom Wellen, a degreed fire
protection engineering technologist. This is provided with the
understanding that the AFSA assumes no liability for this opinion or
actions taken on it and they are not to be considered the official
position of the NFPA or its technical committees.
Copyright (c) 2007, American Fire Sprinkler Association. All Rights
Reserved
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