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Anonymous Poster	air space 04/30/2009 8:45 AM
	How does sufficient air flow created in airplanes which is required for human breathing?
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PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#1 Re: air space 04/30/2009 10:12 AM
	In an airliner, the pressure in the cabin is maintained at the equivalent of 5000ft altitude, and an agreeable temperature for the occupants. The air is circulated and changed at a controlled rate. __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
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lyn Guru Join Date: Oct 2008 Posts: 42355 Good Answers: 1693	#2 Re: air space 04/30/2009 10:21 AM
	It never ceases to amaze me how some of you guys can understand a totally unintelligible string of words pieced together by some of the Guests who seem to have only taken up the language yesterday. Hats off.
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edignan Guru Join Date: Jun 2006 Location: Borrego Springs Posts: 2636 Good Answers: 62	#3 In reply to #2 Re: air space 04/30/2009 10:41 AM
	We are totally guessing and I am frequently answering the wrong question even with native english speakers __________________ "If you want to get somewhere else, you must run at least twice as fast as that!"
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bhrescobar Guru Join Date: Jan 2007 Location: Porto Alegre - RS - Brazil 30deg01'39.73"S 51deg13'43.45"W Posts: 831 Good Answers: 28	#5 In reply to #3 Re: air space 04/30/2009 1:11 PM
	Indeed... __________________ Humm... suspicious you are...
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edignan Guru Join Date: Jun 2006 Location: Borrego Springs Posts: 2636 Good Answers: 62	#4 Re: air space 04/30/2009 10:49 AM
	Giant air compressors are run off the engine's bleed air (called air packs) which are fed into the cabin as a constant flow, then pressure so you can breathe it is maintained by an outflow valve that releases it. No aircraft are strong enough or tight enough to maintain sea level atmosphere, so the cabin is allowed to climb generally to as high as 8,000ft, then slowly repressurized as you descend. __________________ "If you want to get somewhere else, you must run at least twice as fast as that!"
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bhrescobar Guru Join Date: Jan 2007 Location: Porto Alegre - RS - Brazil 30deg01'39.73"S 51deg13'43.45"W Posts: 831 Good Answers: 28	#6 In reply to #4 Re: air space 04/30/2009 1:19 PM
	... if there's no problem in between, that's why there are the emergency oxygen equipment... I just would like to make clear that the air is compressed and bled directly from the engines compressors (specifically at two different stages, depending on the engine operational regimen in the moment), passes through pressure and temperature controlling devices like valves and heat exchangers, and made available to the pneumatic system. Then, one of the clients of the pneumatic system is the air conditioning system, that have those conditioning air packs, that regulates air flow and temperature sent to the cabin. And then, there are the outflow valves, that control the amount of air being exhausted from the fuselage in a certain amount: if more air flows in the cabin than is exhausted, pressure builds up. If more air is exhausted than admited, pressure drops. Of course, computers controll all those stuff, and there are stand by and manual backup systems. A lot of variations exist, depending on aircraft size, engines architecture, the age of the aircraft project, number of engines, etc. Newer concepts like those new GENX engines, do not use engine bleed to improve fuel efficiency. This is new to the market, and it seems that new models will use autonomous electric driven compressors to pressurize the cabin. __________________ Humm... suspicious you are...
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edignan Guru Join Date: Jun 2006 Location: Borrego Springs Posts: 2636 Good Answers: 62	#7 In reply to #6 Re: air space 04/30/2009 1:36 PM
	Newer concepts like those new GENX engines, do not use engine bleed to improve fuel efficiency. This is new to the market, and it seems that new models will use autonomous electric driven compressors to pressurize the cabin. Cool update - thanks! I've been away too long obviously. So Brazil and aviation implies you are affiliated with either TAM or Embraer? Not to pry.... __________________ "If you want to get somewhere else, you must run at least twice as fast as that!"
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bhrescobar Guru Join Date: Jan 2007 Location: Porto Alegre - RS - Brazil 30deg01'39.73"S 51deg13'43.45"W Posts: 831 Good Answers: 28	#8 In reply to #7 Re: air space 04/30/2009 7:29 PM
	Ok, I can update you a little further so... Talking about operators currently in Brazil, there are TAM (airbus family including large body), Gol (Boeings B-737 NG and classic), Azul (brand new ERJ 170 and 190), Trip (heavy turboprops like ATR42), Passaredo (heavy and light turboprops like ATR's and EMB120), and minor ones, TAM and Gol being the bigger ones. Azul is coming up to shake them in a near future. TAM has a little heavier maintenance facility. The rest do not. I am myself an ex-VARIG airlines - remember this name? Well, a lot of people from VARIG is currently working with Azul. Some remaining ones are still working in the ex-maintenance facilities of VARIG, currently owned by TAP Portugal. Check out www.tapme.pt and follow the link for the brazilian facility. Well, there I am... third company, same place, same job. First worked as shop engineer and system manager for pneumatics, then went to APU's, and now accumulating with turboprop engines. But I see per your previous posts that you're also involved in some kind of aerospace stuff. How do you like it? Regards. __________________ Humm... suspicious you are...
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edignan Guru Join Date: Jun 2006 Location: Borrego Springs Posts: 2636 Good Answers: 62	#9 In reply to #8 Re: air space 05/01/2009 8:46 AM
	Ah, when I reached it was for heavy maintenance or manufacture - wasn't thinking about operators. Ehhh, avionics is like the military - military is 90% boredom, 10% fighting for your life Avionics there is a feast on the table, or famine everywhere I generally work by project, and airframes launch new airframes to compete - so there is rarely just one new airplane coming out; there is the first, and whatever is going to compete, and then some new opportunities being filled by other aircraft. So one year we can't meet demand for new systems, next year wondering if unemployment pays well But overall it has been tons of fun! __________________ "If you want to get somewhere else, you must run at least twice as fast as that!"
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bhrescobar Guru Join Date: Jan 2007 Location: Porto Alegre - RS - Brazil 30deg01'39.73"S 51deg13'43.45"W Posts: 831 Good Answers: 28	#10 In reply to #9 Re: air space 05/01/2009 7:27 PM
	I see. Another avionics... I have a few friends here that work exactly as you mentioned. They do special projects and certifications for things like on board entertainment system, TCAS installation, avionics upgrade... Besides they work only in times to times, they still do great results in their workgroup. Myself dealing with mechanics and specifically maintenance (not only engines do wear, but people has a special talent to damage them by ignoring manual instructions or striking the propeller with something...), I would tell you that I am 100% fighting, and always wondering if the payment will cover the bills... After all, yes, I agree: lots of fun. Specially when you have to explain to other people the numbers in the business. Even other engineers sometimes just are not able to understand prices, power scales, sizing, I always have good moments while trying to buy some equipment to build something for a test setup or so, and sellers look at me with that interrogation in the face. I really hope I am able to continue working with it. Good to hear from you, and best wishes in these hard times economy is facing. __________________ Humm... suspicious you are...
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edignan Guru Join Date: Jun 2006 Location: Borrego Springs Posts: 2636 Good Answers: 62	#11 In reply to #10 Re: air space 05/04/2009 8:51 AM
	And you too, (best wishes and good luck). Thank heavens for the FAA, or maintenance would be having to "justify" itself in the boardroom to the bean counters. __________________ "If you want to get somewhere else, you must run at least twice as fast as that!"
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Users who posted comments:

bhrescobar (4); edignan (5); lyn (1); PWSlack (1)

You might be interested in: Breathing and Ventilation Air Systems, Air Velocity Flow Sensors, Gas Flow Meters

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