I have to agree with Justin's definition of Low-level: It is referring to the area being protected - the low areas at the floor where a flammable liquids pool fire would exist. I'm sorry, but I don't have the source of that definition.
I don't want to speak for the US Air Force, but I believe they have moved to the Hi-ex system for a few reasons (they are well aware of the other options and have consciously selected Hi-Ex): 1. Environmental problems relating to AFFF and its disposal 2. Cost of AFFF foam and the amount used in any discharge - accidental or otherwise. Hi-ex systems use much less concentrate and usually have little problems with disposal 'down the drain'. 3. Relative reliability of Hi-ex vs AFFF through monitor nozzles. Too often the monitors get obstructed. I don't think the Viking grate system was out when they switched to Hi-Ex, but that system still has the drawbacks listed above. 4. Hi-ex is generally 'drier' than AFFF discharge, so the damage potential to aircraft or components through contact with the discharge is reduced. FYI - the hi-ex requirements of the air force include 1 meter deep foam throughout the protected space within 4 minutes; and 90% of the plane's silhouette covered to any depth within 1 minute. Mark A. Sornsin, PE Fire Protection Engineer Ulteig Engineers, Inc. 3350 38th Avenue S. Fargo, ND 58104-7079 Direct: 701. 280.8591 Fax: 701.280.8739 Cell: 701.371.5759 [email protected] www.ulteig.com Confidentiality Notice This message may contain privileged and confidential information. If you think, for any reason, this message may have been addressed to you in error, you must not disseminate copy or take any action in reliance on it, and we would ask you to notify me immediately by return email to [email protected]. -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of DerBlitzkrieger Sent: Saturday, May 30, 2009 2:10 AM To: [email protected] Subject: Low level foam systems Hello, I'm reviewing the design and installation for a Group I aircraft hangar of Type I construction. The plane being worked on is a C-130J-30 and its wing area doesn't excced 3000 ft², so I only need a sprinkler system, and a low level low- or high-expansion foam system. My problem is, I cannot find a definition for what a low-level foam system is. IE, max foam generator height, etc. I've checked NFPA 11, 16, 409, and the glossary of terms. That's somewhat academic, as the system designer opted instead to go with a roof level high expansion foam system using blower type generators, and using the sprinkler system to actuate the system. This seems like the total flooding roof level system would be a better protection route than anything a low-level system could provide. What do you think? And what exactly makes a low-level foam system low-level? I would appreciate any insight into this. Thanks, Ben Young, CET Fire Protection Construction Lead DynCorp AFCAP _______________________________________________ Sprinklerforum mailing list http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
