American Fire Sprinkler Association
12750 Merit Dr., Suite 350 Dallas TX 75251
Ph: (214) 349-5965 Fax: (214) 276-0908
------------------
Technical Update
January 30, 2009
------------------
“Is it the intent of 5.14.6.5 and Figure A.6.3.1 of NFPA 20 to require
flexible couplings for strain relief when the interconnecting suction
piping is installed approximately 6 ft below final grade in accordance
with NFPA 24?”
We have reviewed NFPA 20, 2007 Edition that you indicated as the
applicable standard. Our informal interpretation is that strain
relief is provided by the joints in the ductile iron pipe.
The Handbook for Stationary Fire Pumps commentary indicates the
purpose of strain relief is to prevent damage to the pump suction
flange. A series of grooved couplings in the suction pipe provides
flexibility should the pump or tank foundations begin to settle and
should also provide for limited movement due to expansion and
contraction. Your situation is a firewater reservoir with the fire
pump house located at a lower level with 60 ft length of underground
pipe. Each connection of the ductile iron pipe will provide 1 to 3
degree angular movement depending on the manufacturer and that
flexibility meets the intent of 5.14.6.5 for strain relief. If the
drop between the firewater reservoir and the pump suction drops 20 to
30 ft, the change in elevation may reduce the angular movement of the
piping. Then consider a flexible coupling inside the fire pump house
on the suction flange to remove any question of strain on the suction
piping.
-----------------
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 © 2009, American Fire Sprinkler Association. All Rights
Reserved
--------------------------
If you’d rather not receive future faxes from AFSA, fax your removal
request to Amy Sweeney at Efax (214) 242-3155 or call toll free (888)
839-4830 or send e-mail request @ [email protected]. Please
include your company name and the specific fax numbers(s) at which you
do not wish to receive faxes from us. Our failure to comply with your
request may be unlawful.
_______________________________________________
Sprinklernotes mailing list
[email protected]
http://lists.firesprinkler.org/mailman/listinfo/sprinklernotes
