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Cabin Humidifier/Lower Altitude Pressurization Question?

Posted: Sun Jan 20, 2019 1:19 am
by NateGreat
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?

Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Posted: Sun Jan 20, 2019 1:55 am
by alfa164
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.

Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Posted: Sun Jan 20, 2019 2:05 am
by travaz
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?

Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Posted: Sun Jan 20, 2019 3:14 am
by Starlionblue
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.

Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Posted: Sun Jan 20, 2019 4:07 am
by travaz
OK Thank You for the info.

Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Posted: Sun Jan 20, 2019 9:14 am
by Tristarsteve
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.

Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Posted: Sun Jan 20, 2019 12:17 pm
by BravoOne
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.

Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Posted: Sun Jan 20, 2019 3:10 pm
by SteelChair
Does anyone know which airlines chose to get the option for humidity and those who didn't? And on which types?

Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Posted: Sun Jan 20, 2019 3:54 pm
by BravoOne
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?

Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Posted: Sun Jan 20, 2019 4:40 pm
by CosmicCruiser
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?

Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Posted: Sun Jan 20, 2019 4:41 pm
by SteelChair
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

Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Posted: Sun Jan 20, 2019 5:01 pm
by BravoOne
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.

Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Posted: Sun Jan 20, 2019 11:27 pm
by Starlionblue
There is a "Cockpit Humidifier" as an option on the A350. Nothing for the cabin though. Same as the 787 one mentioned by BravoOne.

Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Posted: Mon Jan 21, 2019 11:03 am
by BravoOne
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?

Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Posted: Mon Jan 21, 2019 12:32 pm
by expat92
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

Re: Cabin Humidifier/Lower Altitude Pressurization Question?

Posted: Mon Jan 21, 2019 1:32 pm
by BravoOne
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.