Dump Valve(SMACCS)
Thread Starter
Joined: Jul 2014
Posts: 1
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From: Korea
Dump Valve(SMACCS)
Hi Guys,
When I was looking at the Pack system of B747 Freighter, I found something I couldn't understand exactly.
You may find Dump Valves(SMACCS) in Pack's(No.1 and No.3)
The question is Why Freighter needs Dump valve.
Manual just said Dump valve restrict airflow to Pack's But I just thought FCSOV has this function(Shut off) and I found this valve is related to fire protection system for main deck cargo.
I know that fire in main deck cargo can be removed with depressurizing it.
can anyone explain that to me?
When I was looking at the Pack system of B747 Freighter, I found something I couldn't understand exactly.
You may find Dump Valves(SMACCS) in Pack's(No.1 and No.3)
The question is Why Freighter needs Dump valve.
Manual just said Dump valve restrict airflow to Pack's But I just thought FCSOV has this function(Shut off) and I found this valve is related to fire protection system for main deck cargo.
I know that fire in main deck cargo can be removed with depressurizing it.
can anyone explain that to me?
Joined: Mar 2009
Posts: 273
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From: Kerikeri, New Zealand or Noosa Queensland. Depending on the time of year!
It is a long time since I last flew the B-747 but if my memory serves me correctly the purpose of the Dump Valve is to over ride the control of the Out Flow valves and drive them to the full "Open" position, thereby depressurising the aircraft.
Joined: Apr 2004
Aviation Qualifications: LAME
Posts: 2,279
Likes: 186
From: Dorset UK
Don't know about the 747F, but IIRC on some A300B-4 cargo conversions, (the ones done at Bristol), when a main deck smoke warning occurred, the main deck air supply was shut off and a dump valve opened to divert some of the air into the lower cargo bays to avoid over pressure in the ducts.
Hope this helps.
Hope this helps.
