Flight Crew Portable Oxygen

[737incognito]

We have 311 litres portable O2 bottle on 737 with demand regulator for constant 3 litres flow or On-demand 100% O2 but I can not find guidance on which one to chose in different non-normal situations (checked FCOM and SOP).
I guess on-demand at higher altitudes but i would like to hear some "official info" if somebody care to share.
Thanks

[Rainboe]

Should it not be left on the On demand, 100% setting? This is the pilots' oxygen we are talking about!

[737incognito]

Just to be clear - I'm talking about PORTABLE crew oxygen. I'm not sure what is it used for and when.

[BOAC]

It depends on which mask you have attached. Full face, as Rainboe says. Rebreather, t'other.

[David Horn]

Is it possible that the 3l/min is for medical purposes if necessary?

[737incognito]

It's connected to full face mask to on-demand 100% O2 outlet. I guess it can be used as reserve for normal crew O2 masks at any level for period specified in FCOM (depending on consuption depending on activity level from 7 to 71 min). I dont know what else could it be used in this configuration.
Also I was told (not confirmed) that cabin portable O2 masks can be connected to other (constant 3 litre flow) outlet. I would like to know what would be situation to use bottle in this config. I'm worried that O2 partial press would not be enough for all levels decompressions.

Finaly what would be procedure if for some reason crew O2 press. is depleted during the flight.

[Dani]

If you are talking about portable Oxy, then it's thought for the cabin. There are different brands, ours has 2 outlets, one for 4 liters/min and the other for 2. There is one mask attached and one spare. You use it for passengers who feel sick or to recover after a decompression.

The 4 liters is for adults in the beginning, you can change to 2 if they feel better. 2 is for children and infants.

Our masks are never 100%, they are mixed with ambient air, that's why they're not suitable for smoke conditions. For that you have the PBEs, eigther Scott or Dräger.

Maybe I could help,
Dani

[737incognito]

Yes we have those too, but I'm talking about cockpit.

[nitro rig driver]

We have 311 litres portable O2 bottle on 737 with demand regulator for constant 3 litres flow or On-demand 100% O2

and then later

Just to be clear - I'm talking about PORTABLE crew oxygen


A 311 litre portable bottle :confused::confused:

[737incognito]

Yes, it is charged to 1800 PSI so it doesn't take much space (just a little biger than cabin portable O2) and it is B737 standard emergency equipment.

[Lazymech]

I've never seen a portable O2 bottle in a 737 cockpit, so i don't think it's standard equipment, what's the use if there is a normal crew o2 bottle installed?

Out of interest, where do you store the portable bottle? it's not like there's a lot of space left on the 737 flightdeck

[Short_Circuit]

Flight deck portable oxy cylinders here in Oz have 100% outlets that the crew “quick don” masks connect to, masks that have their own regulator intergral to the mask. It can be used as supplemental oxy for crew, walk about oxygen for crew in smoke & has 4ltr / min outlet for pax re-breather or tracheotomy masks. I guess you would have similar.
S_cct

PS. A link from Aus CASA on oxy system specs.
http://casa.gov.au/download/orders/CAO108/10826.pdf

[737incognito]

Does anybody have a procedure for situation when Crew o2 is depleted. What would be max level to continue the flight? I know 10000' is an abvious answer, but since aircraft flying bellow FL250 do not need on-demand masks with integrated microphone (don't they?) I was studying posibility of descendin to only FL250 while ensuring portable oxygen is available to crew in case of (unlikely) decompression.

[mono]

Gonna be a pedant here and agree with Nitro rig driver.

A litre is a unit of volume. How can you have a PORTABLE oxygen bottle of 311 litres??????

I doesn't matter if it is at 14.7 psi or 1800 psi the volume will still be 311 litres that's 68 gallons??? that's an awful lot to heft around the cabin or cockpit.

The cabin bottles are 1.5/2/2.5 depending on the size. They too are pressurised to 1800 psi nominal but guess what?? they're still only 1.5/2/2.5 ltr or whatever.

Crew masks are usually 100% on demand. The pax have a constant flow setting.

[BOAC]

Pedants accepted, but this is how Boeing describe the bottle, so there!

"The portable oxygen cylinder is installed behind and adjacent to the First Officer’s seat. When charged to 1800 psi at 70° Fahrenheit (21 ° Celsius), it contains 11 cubic feet (311 liters) of free oxygen."

It has always been known (in my experience) as a '311ltr bottle'

[737incognito]

I guess it means that if you release all that O2 from the bottle to a normal pressure it would take 311 litres of space
Cabin bottles are 2 or 4 litres per minute of O2 flow. As they can be used for much more than one minute...