Fire Protection question on SFPE Ref Manu. Book

[HERO]

Hello,

On page 233, problem 3: we have a 6" pipe which contains 180 gasketed joints and three 6" bronze steated gate valves. The question asks us to determine the allowable leakage quantity during a 2 hour time 220 psig hydrostatic test.

In the old NFPA 24-2002, section 10.10.2.2.4( 1), we the use the ratio 2 qt/ht per 100 gaskets or joints to determine the leakage flow rate. For the gate valves, use 10.10.2.2.4 (2), to help us determine the allowable leakage flow rate. We then add the two leakage flow rates and multiply that number by the time factor which gives us the allowable leakage quantity.

However, in the new NFPA 24-2007 edition, when you look that same section 10.10.2.2.4, we have to determine allowable leakage quantity flow rate via equation 10.10.2.2.4 (a). Subsection 1, 2, 3, and 4 are gone! NFPA rewrote the entire code section.

My question: how do I do convert 180 gasketed joints into equivalent length of pipe? I think I’m missing something here. Any input from the Fire Protection or engineering communities is greatly appreciated!

Thank you,

Mark

 

[Capt Worley PE]

The test was written using 2002 NFPA 24, but 2007 edition is now valid, so I don't know how I'd go about choosing what to do on the test, but at the office I'd calculate it using 2007 NFPA 24 10.10.2.2.4(a).

 

[HERO]

worley,

When your engineers calculate the leakage rate, they set S = straight pipe + fittings. Am I correct?

Mark

 

[Capt Worley PE]

S is the total length of the tested pipe.