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Foam Proportioning

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ChrisSam

Mechanical
Joined
Feb 28, 2020
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Hi Everyone.

I am a Mechanical Engineer working for a Fire & Safety company for the Oil and Gas.
I have been doing some foam proportioning tests, according to NFPA 11, and every time i do it, the foam proportion fails.

Synopsis of the Bladder tank:
1200 Horizontal bladder tank with 1 1/2" water inlet piping and 1 1/2" foam outlet piping to a 4" proportioner or ratio controller (RC) with 0.700 inches orifice size. There is a pressure reduction valve upstream of the bladder tank which takes 96 psi to the bladder system. The type of foam used is 3x6 AR AFFF foam.

Test:
I have used flow rates of 570 gpm and 950 gpm and both times these foam proportion have failed. I am using a conductivity meter and also refractive meter. Both show that the foam is proportioning at 5.2% and 6% as it should be. The tests are also conducted with the system water which has a pH level of 7.5.

Please lend some assistance.

Thank you.
 
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