Brian,
My approach would be as follows:
1) Refer the AHJ to section 4.6.2.3.1 of NFPA-20, 2010, which states
[emphasis mine]:
/4.6.2.3.1 Where the maximum flow available from the water supply cannot
provide a flow of 150 percent of the rated flow of the pump, but the
water supply can provide the greater of 100 percent of rated flow or the
maximum flow demand of the fire protection system(s), the water supply
_*shall be deemed to be adequate*_. In this case, the maximum flow shall
be considered the highest flow that the water supply can achieve
/
2) Follow the requirement in 4.6.2.3.2 which requires that a sign be
added to the pump room, to advise any future testing personnel that the
available water supply does not allow for testing to 150 percent of
rated capacity:
/4.6.2.3.2 Where the water supply cannot provide 150 percent of the
rated flow of the pump, a placard shall be placed in the pump room
indicating the minimum suction pressure that the fire pump is allowed to
be tested at and also indicating the required flow rate./
3) Similar language is provided in section 4.6.5.1, and 4.6.5.2 of
NFPA-20, 2010 [emphasis mine]:
/4.6.5.1 Except as provided in 4.6.5.2, the head available from a water
supply shall be figured on the basis of a flow of 150 percent of rated
capacity of the fire pump.
4.6.5.2 Where the water supply cannot provide a flow of 150 percent of
the rated flow of the pump, but the water supply can provide the flow
demand of the fire protection system, the head available from the water
supply _*shall be permitted*_ to be calculated on the basis of the
maximum flow available as allowed by 4.6.2.3.1.
/
Seems to me from reading this, that his concerns of the pump running up
to 150% of capacity drawing his municipal main down to 18.7 psi has been
addressed by the NFPA-20 committee.
sincerely,
--
PARSLEY CONSULTING
Ken Wagoner, SET
760.745.6181 voice
760.745.0537 fax
[email protected] <mailto:[email protected]>e-mail
www.ParsleyConsulting.com <http://www.ParsleyConsulting.com>website
IMPORTANT NOTICE: This correspondence is not a Formal
Interpretation issued pursuant to NFPA Regulations. Any opinion
expressed is the personal opinion of the author and does not necessarily
represent the official position of the NFPA or its Technical Committees.
In addition, this correspondence is neither intended, nor should it be
relied upon, to provide professional consultation or services.
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