Date: Tue, 6 May 2003 22:07:04 +0100 From: "**-**" <m.faulksnopsamternet.com> Subject: Re: Okay, why?
"Paul Halliday" <pjghnopsamyonder.co.uk> wrote in message news:BADDABEE.5FF1%pjghnopsamyonder.co.uk... > Okay, so the classic 900 heat vent control is powered by vac and has a > canister to hold vac when the car is in turbo. Why? Why not use a mechanical > setup, or an electric powered motor? > > How far back into Saab's history does this innovation (if that is the word) > go? Is this setup still used on new/er Saabs? Which other cars use this > setup? > > Inquisitive minds need to know. > > Paul > > 1989 900 Turbo S > http://saab.go.dyndns.org/ > To give you a pure aircraft engineering answer, A conventional switch/motor always runs the risk of creating a spark in an oxygen rich enviroment this can lead to catastrophic fire (Certain US Space Program Anyone?). With pneumatics there is no risk of a spark. Admitantly under the dash of your C900 isn't oxygen rich or flammable but its nice to have. Matt