NateGreat
Topic Author
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Cabin Humidifier/Lower Altitude Pressurization Question?

Sun Jan 20, 2019 1:19 am

What’s the deal with the systems onboard planes such as the Airbus A350, Boeing 787, and future Boeing 777X that allow the cabin to be pressurized at a lower altitude, and humidity to be pumped into the cabin? Are those systems something that can be retrofitted onto older planes such as the Airbus A330, Airbus A330neo, and Boeing 777-200/300?
 
alfa164
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Joined: Sat Oct 06, 2012 2:47 am

Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Sun Jan 20, 2019 1:55 am

NateGreat wrote:
What’s the deal with the systems onboard planes such as the Airbus A350, Boeing 787, and future Boeing 777X that allow the cabin to be pressurized at a lower altitude, and humidity to be pumped into the cabin? Are those systems something that can be retrofitted onto older planes such as the Airbus A330, Airbus A330neo, and Boeing 777-200/300?


Older planes were forced to fly with a lower humidity not only because of the higher altitude pressure, but also because moisture caused corrosion in their (non-composite) skins. The newer aircraft using composites avoid that problem.

Adding humidity to older frames would limit their lifetime severely.
I'm going to have a smokin' hot body again!
I have decided to be cremated....
 
travaz
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Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Sun Jan 20, 2019 2:05 am

Is the humidity increased by introducing water vapor from some sort of tank or is it taken from the outside air? I know at altitude the air is very dry. So how is the humidity increased?
 
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Starlionblue
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Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Sun Jan 20, 2019 3:14 am

travaz wrote:
Is the humidity increased by introducing water vapor from some sort of tank or is it taken from the outside air? I know at altitude the air is very dry. So how is the humidity increased?


There is no moisture added. You actually answered your own question: "...at altitude the air is very dry". The moisture content in the air decreases with decreasing pressure. Thus, a higher pressure cabin has more humidity.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
travaz
Posts: 853
Joined: Wed Jun 13, 2001 1:03 am

Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Sun Jan 20, 2019 4:07 am

OK Thank You for the info.
 
Tristarsteve
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Joined: Tue Nov 22, 2005 11:04 pm

Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Sun Jan 20, 2019 9:14 am

Swedish firm CTT make humidity control systems

https://www.ctt.se/cair-vip/how-it-works/

Sole source supplier on all nextgen widebodies

Boeing 777X – Humidifier for FD, OFCR, OFAR, Cabin Zone 1 & 2

Boeing 787 – Zonal Drying™ standard and Crew Humidifier 0ptional

A350 – Cair™, Crew Humidifier and Zonal Drying™ optional

A380 – Crew Humidifier optional

allproducts-A350

Was standard on B787 but no longer.
 
BravoOne
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Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Sun Jan 20, 2019 12:17 pm

Had a humidifier for them main cabin of a privately owned 757. To say it was maintenance intensive is an understatement. Don't know who manufactured this system.
 
SteelChair
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Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Sun Jan 20, 2019 3:10 pm

Does anyone know which airlines chose to get the option for humidity and those who didn't? And on which types?
 
BravoOne
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Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Sun Jan 20, 2019 3:54 pm

SteelChair wrote:
Does anyone know which airlines chose to get the option for humidity and those who didn't? And on which types?


On what airplane are you asking about?
 
CosmicCruiser
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Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Sun Jan 20, 2019 4:40 pm

BravoOne wrote:
Had a humidifier for them main cabin of a privately owned 757. To say it was maintenance intensive is an understatement. Don't know who manufactured this system.


it's my understanding that originally the MD-11 had a humidifier and Fedex disabled it for the exact reason you mention. Just as it disabled drooped ailerons. Any FX maint guys here?
 
SteelChair
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Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Sun Jan 20, 2019 4:41 pm

BravoOne wrote:
SteelChair wrote:
Does anyone know which airlines chose to get the option for humidity and those who didn't? And on which types?


On what airplane are you asking about?

Someone posted that it was optional on 787, 350, 380
 
BravoOne
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Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Sun Jan 20, 2019 5:01 pm

I see nothing that would indicate a humidifier system is available for the 787 cabin. Flight deck, yes, (optional) Cabin, no.

The environmental control system provides a relative humidification level within the passenger compartment of 12
percent to 16 percent during normal cruise operation. The air purification system includes ozone removal, high-efficiency particulate air (HEPA) filtration for particulates, and gaseous purification for contaminants.
HEPA-type filtration for particulates is effective at filtering viruses, bacteria, and fungi. The gaseous purification
technology has an absorbent that is integrated with the HEPA filters on the lower recirculation system.

Flight Deck Humidification
The relative humidity within the flight deck is approximately 1 to 2 percent during normal cruise operation. Partial
provisions are supplied for installation of a flight deck humidification system.
 
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Starlionblue
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Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Sun Jan 20, 2019 11:27 pm

There is a "Cockpit Humidifier" as an option on the A350. Nothing for the cabin though. Same as the 787 one mentioned by BravoOne.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
BravoOne
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Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Mon Jan 21, 2019 11:03 am

CosmicCruiser wrote:
BravoOne wrote:
Had a humidifier for them main cabin of a privately owned 757. To say it was maintenance intensive is an understatement. Don't know who manufactured this system.


it's my understanding that originally the MD-11 had a humidifier and Fedex disabled it for the exact reason you mention. Just as it disabled drooped ailerons. Any FX maint guys here?


Never saw or heard of this on any MD11?

On the 747-400 flight deck you could see a white substance all over the overhead CB panels that was deposited by the humidifiers. Not sure if this was an accepted condition, or if it was due to other circumstances when operating this system?
 
expat92
Posts: 18
Joined: Mon Jan 21, 2019 11:03 am

Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Mon Jan 21, 2019 12:32 pm

BravoOne wrote:
I see nothing that would indicate a humidifier system is available for the 787 cabin. Flight deck, yes, (optional) Cabin, no.

The environmental control system provides a relative humidification level within the passenger compartment of 12
percent to 16 percent during normal cruise operation. The air purification system includes ozone removal, high-efficiency particulate air (HEPA) filtration for particulates, and gaseous purification for contaminants.
HEPA-type filtration for particulates is effective at filtering viruses, bacteria, and fungi. The gaseous purification
technology has an absorbent that is integrated with the HEPA filters on the lower recirculation system.

Flight Deck Humidification
The relative humidity within the flight deck is approximately 1 to 2 percent during normal cruise operation. Partial
provisions are supplied for installation of a flight deck humidification system.


Am I missing something? Is this level healthy for the pilots? The internet would suggest not but it is the internet!!!

"Humans can be comfortable within a wide range of humidities depending on the temperature—from 30% to 70%—but ideally between 50% and 60%. Very low humidity can create discomfort, respiratory problems, and aggravate allergies in some individuals." source:wikipedia.

expat92
 
BravoOne
Posts: 3587
Joined: Fri Apr 12, 2013 2:27 pm

Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Mon Jan 21, 2019 1:32 pm

Dunno. Have many hours flying jets and haven't suffered any issues from it yet. I think the key word here is "some" so take it for what its worth.

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