air re-circulation

[nooluv]

Can anybody tell me how often the air in the passenger cabin re-circulates during a short flight? How often is the cabin renewed with clean air?
Is it different on long haul?

Thanks

[Knold]

It varies with aircraft type and systems equipped.
Some planes take in new air all the time. These are usually the older ones.
Some planes recirculate used air and ads only a smaller amount of new air. This is more common on newer planes.

[SQ Fugitive #2]

During long haul flights most a/c aircon packs run at a reduced rate in order to reduce fuel usage. Bleed air from the engines continualy enters the cabin to pressurise the aircraft but the aiconditioning packs operate at a ruduced flow which is automatically controlled on the 744.
On aircraft like the 737 the aircon packs operate at a constant flow.
In all cases cabin air is reciculated throughout the aircraft continually. (Except in the event of cabin or aircon smoke where it is switched off)

[BOAC]

nooluv - found using search (http://www.pprune.org/forums/search.php?s=) (links bar top right)

this thread (http://www.pprune.org/forums/showthread.php?s=&threadid=12116&highlight=recirculation)

[expedite_climb]

On the 757 the complete cabin air is refreshed approx every few minutes.

[Capt Claret]

Dibble&Grub posted a link on this very subject, in response to a SARS related thread on Dunnunda.

The article is very interesting and the link is reproduced below.

http://www.boeing.com/commercial/cabinair/ecs.pdf

[nooluv]

Thanks everyone for the info!

mal.com-nooluv.......