A/c train
Topic Author
Posts: 674
Joined: Sun Jun 10, 2001 7:57 am

Cabin Condensation

Tue Jun 12, 2001 1:23 am

When we last went to Florida, after we had landed and arrived on the Apron I noticed some condensation , almost like water Vapour or steam coming out from just below the overhead bins, now I know that some cabin air is recirculated but some is new air, but what is going on, is it something to do with the heat in Florida? it looked like it was almost being sprayed out, this was an A330 by the way,
cheers
A/c
 
crjmech
Posts: 257
Joined: Wed Jun 07, 2000 6:31 am

RE: Cabin Condensation

Tue Jun 12, 2001 2:20 am

Like the saying goes, "It's not so much the heat as it is the humidity." If the air entering the a/c system is high in water vapor content, the moisture will condense as it is compressed by the ACMs and appear as a fog-like vapor. The same principle causes the "smoke" often seen streaming from the wingtips of airliners as they land.
Thou shalt mind thine altitude,lest the ground reach up and smite thee.
 
crjmech
Posts: 257
Joined: Wed Jun 07, 2000 6:31 am

Disregard Last Transmission!

Tue Jun 12, 2001 3:07 am

What was I thinking? The condensation I described is driven by a decrease in temprature which is sometimes due to a drop in pressure, not an increase as I said earlier. The vapor you saw in the cabin was probably due to the crew setting the packs at a relatively cold temp, causing the water in the humid Florida air to condense and form fog. The example of the wingtip vorticies is also due to a drop in temprature, this time driven by a corresponding decrease in air pressure over the wing (remember Ma and Pa Bernoulli's boy). An example more readily apparent to those of us in the maintenance dept. is the fog that forms in the cabin while "dumping" the pressure built up during a ground pressurization run. Sorry for the earlier numb-skullery and if this explaination is full of holes, let me know 'cause I'm starting to get a little confused myself!
Thou shalt mind thine altitude,lest the ground reach up and smite thee.
 
JT-8D
Posts: 423
Joined: Sun Dec 31, 2000 11:34 pm

RE: Cabin Condensation

Tue Jun 12, 2001 3:21 am

CRJ, nice save dude. My buddy and I had to pressurize an md-80 to leak ck a door. We took it to about 6 psi. I asked him to take it easy on the way down, he just grinned, and pulled the handle back to auto. Dumped the cabin in about 3 seconds. I wasnt sure if the fog I saw was due to the pressure reduction, or my brain exploding--lol. PS, dont forget about ma and pa Boyles little boy, or his pal Charles. They both have pressure related rules named after them. Bet they where fun at parties..JT
 
VC-10
Posts: 3546
Joined: Tue Oct 26, 1999 11:34 am

RE: Cabin Condensation

Tue Jun 12, 2001 5:51 am

Once, on a very rare hot day at LHR I felt sorry for the cleaners so I put the packs on, turned the trim air off, and turned the cabin temp selector to full cold. Guess what - in less than a minute I had it snowing inside the cabin ! Needless to say, but I will anyway, I didn't leave too long in that condition.
 
N312RC
Posts: 2586
Joined: Mon Aug 28, 2000 10:58 am

RE: Cabin Condensation

Tue Jun 12, 2001 7:04 am

That has happened on just about every Delta flight ive been on out of Florida. Always wondered. Thanks!
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