Oxygen Systems (was O2 Flows w/Switch Off)

[Paul Sharp]

Yesterday while doing some testing (just up to FL 200 but enough to need to use the O2 system) on my 1967 T337B, I noticed that the oxygen flows when the masks are plugged in even if the O2 system lever is in the "Off" position. Is this normal? Or does it indicate that the lever isn't working? Or ???

[kevin]

Paul,

It is not normal for oxygen to flow with the valve off. Your regulator probably needs to be overhauled. If you have all your masks unplugged, oxygen should not flow even with the valve ON. But with the valve off, your most likely culprit is the regulator.

Blue skies,

Kevin

[rick bell]

my p73 ox switches were mis-labeled. spent a lot of time looking for leaks,but to no avail. we finally checked the physical positon
of the switch to verify what direction open and close were. the label was backward, so when it said closed it was open and it would drain the bottles within 4 or 5 days

[Paul Sharp]

Mine isn't flowing with no masks plugged in. And when it's "Off" it doesn't leak out.

The basic inquiry is why it flows in the "Off" position when you plug in a mask and look at the flow indicator. Sounds like that shouldn't be happening either. I'll have to have the mechanics look at the valve and see if it really is turning off when you flip the lever that direction.

[WebMaster]

My system is out of inspection, needs a new pressure test, but here's my fundamental question. I have found one pilots mask for the plane, but no other units. How hard/expensive is it to find the canulas, where can I get them, and realistically, how often do non-turbo people use them? I am out of throttle at 7000, and have only flown 8000 on my trip to the Bahamas. We are here in the midwest, where there are no mountains or things to fly around.

[Bob Cook]

Larry

You may want to consider removing the oxygen bottles and plumbing on your next annual. You can save a lot of weight. Depending on the size of bottles, you are carrying around another 50 or more pounds (guessing). Check your equipement list for weight.

I put in a four place sky-ox system to replace the VALUE-JET cannisters. The total system was about 450$ and included a quick-doning mask. U can buy new oxy-saver cannulas from sky-ox to fit the 337 cessna outlets. check their web site. They use less oxygen than normal cunnulas.

I flew a 310 at 12k ft quite often and never seemed to have any difficulty (when younger).

It is nice to have insurance during the summer when you need to climb out of the "crap" to see where you are going (best reason for oxygen).

Normally asperated ? takes too much time.....

Bob

[Keven]

Bob:

Does the sky ox system fit in the place of the normal oxygen system in the skymasters? I.e., would I use the same plumbing behind the headliner, or does it go someplace else?

I've still got the plumbing and carriers, but no oxygen cans installed right now. I was going to get it back up to speed with cans, but just haven't gotten around to it yet.

You're right, it does take awhile to get up that high in normally aspirated, but there have been a handful of times already just in the past year that I could have really used it, i.e., ice, communication improvement, excessively improved winds, etc.

Thanks,

Keven
________
Medical Marihuna Dispencary (http://dispensaries.org)

[Bob Cook]

Keven
1)portable systems : see below.
2) confused when you say "cans". Think you mean oxygen "bottles".
3) additional info;
In the P versions you could go for the canisters that are one-time usage for 20 minutes. It costs about 1000 dollars to replace them. The rear is slightly larger with three outlets. I removed the generators per a manidory SB whereas all canisters must be replaced within 10 yrs.
BTW these were made by SCOTT. During the annual we removed one and fired it off. The surface temp of the cannister rose to 240 deg. F. I was concerned about these creating a fire. Apparently a couple of Malibu's were lost because of the temps.

The other factory option was a built in system. I saw back last fall where someone such as preferred had some oxy tanks for sale but the upkeep and weight is a pain. You need to have them pressure tested and the "plane" refills are not cheap!
Skyox and others have some light weight aluminum bottles. My "D" sized bottle is located in the base of a centre console between the seats (out of the way).

With the skyox or equivilant you can carry it as a portable and they have a carriers for the back of the seat. just do a web search on AVWEB for the info. In the long run it was cheaper and easier to handle. I use oxgen at night or when I am tired and need to wake up and feel refreshed. Does great for poor vision at night. I recommend use of oxygen at night above 8k ft.

It is nice to climb out of the "crap" regardless of type! This includes getting away from VFR weekenders playing with their new GPS's ....... <G>.

Bob

[SkyKing]

Bob,

Can you tell us the model number, etc., of the SkyOx system you opted for?

I have one of those center consoles between the seats too and I think there's room for a slim aluminum bottle like you've installed -just the perfect thing for a whiff at night or on a long trip before landing.

SkyKing

[jcthomas]

I just flew my 1969 T337D from Seattle to Indiana, PA. I removed the old system bottles, and they are heavy, because I was advised it is very expensive to replace the parts to get them approved.

I purchased a 24 cu Nelson O2 system. I can carry the tank with hand it is so light. The tank straps onto the back of the seat or anywhere else you want to put it.

Three of us used it for almost six hours at FL 150 and 170 and there is almost a half of tank left. I chose this tank based on an article comparing tanks in Aviation Consumer.

The old tanks are sitting in the hangar.

[Paul Sharp]

I agree on the Nelson stuff. I have bought lots of components from them and found them excellent as well as good for their "oxy-miser" cannulae and etc. They sold out to Oregon Aero or something like that, but same stuff from same designer, etc. Their oxy-miser stuff includes a measurement device with the oxy-miser canula scale on one side and a regular mask scale on the other side so you can read off/set the flow accordingly.

As for the factory system, mine works fine (except for the question I asked that started this thread), and I like having the Nelson portable hanging on the pax seat because if you're at 25,000 and something goes wrong with the O2 system, you don't want to be making some headlong dive to get back to thicker air. Whenever I go that high (my '67 T337B is certificated to 33,000), I hook up a spare mask to the Nelson protable and have it ready so that I only have to twist the knob and slip on the mask.

[kevin]

Paul,

Do you use a pressure demand mask at higher altitudes? I seem to remember something about them being required above 25K or some such...

My P only goes to 20 legally. I envy your altitude capability...

Kevin

[Bob Cook]

I believe the cannulas are good to 20k ft or perhaps 18, above that you need the mask. The sky-ox has adapters for all AC. What I have is a plug then tubing which goes to an oxygen flow meter with a shut off valve then tubing then the quick doning mask. The mask is about 100 dollars. I can turn on the oxygen flow and regulate from my lap. The flowmeter shows with cannula on one scale and mask on the other. The scale goes to 40k ft or higher. Will take a couple of pics and send it to you. You can reduce the flow on any of the cannulas to save oxygen if need be. The pilot can remain concious <G>. Lower rates keep the pax quieter.....

Just make sure there are no leaks in the system.

Kevin,
your aircraft can go higher, you need to dump the pressurization or the cabin will rise to whatever the upper deck air will provide. The "P" ceiling is based on cabin pressure not going above 10k ft. Unless you had an oxygen bottle you can't go higher! Certification was based on getting back to 12k ft in a xxx minutes. The oxygen generators are only good for 20 minutes.

Another reason to have an oxygen bottle. Nelson, skyox, I do not think there is that much difference. I selected skyox because of the cannula design and the flowmeter with shut off. Pain to go to the bottle and mess with the flow rates. It is better to have it in your lap where you can "play" with it to save oxygen if need be.

Bob

[jcthomas]

The Nelson system and I am sure the Sky Ox use the same cannula system. You save a lot of O2 using them. However the key is the type of flow meter you have.

I purchased flow meters with my system that will go to FL250. However, once your above 180FL the cannulas are no longer useable. They supply you with plastic masks to use at that level. The masks cannot be used if you have a thick beard or anything that would cause a leak. If you have a thick beard, then you will have to purchase the more expensive rubber mask. Without the mike built in they are not to expensive. With the mike, it is about 400.00.

My tank is very light and easy to use. Put the cannula on, plug the other end into the tank (snaps in) and turn on the valve, adjust the flow meter to your altitude by turning a vlave and watching the FL ball go to the altitude you choose.

John

[Mark Hislop]

Bob:

You mentioned that the P model can go higher. I know that physically it can go higher. However, I was under the assumption that legally I can't go higher, even with oxygen, because it would violate the certification. Or do I have the option of dumping the prssurization and using the manufacturer's O2 system (tanks, not generators)?

Mark

[Paul Sharp]

The diluter demand and pressure demand masks are not "required" by regulation to my knowledge, but are recommended for above 25,000 feet.

Cannulae are approved only for up to 18,000 feet. Above that you are required to use a mask.

The Nelson systems all include the adjustable flow meters inline, where each user can see and adjust as necessary without messing with any flow control at the regulator.

It seems that one can dump the pressurization on a P model and safely take it higher than 20,000 with an oxygen system and masks. The trick would be the legal argument about certification. If anything happend I bet lawyers would have a heyday.

[James Bennon]

Overhauled front engine, had combustion heater checked and was returned from C & D Associate's as not repairable--we re-installed --now we can get nowhere near Max differential at altitude, rechecked seals on heat ex changer, what are we missing????---work perfectly before we overhauled front engine---1973 Pressurized T337G??
A. any suggestions as to where to look---service manual not much help
B. Where is a good Skymaster shop -- we are located ion West Virginia??

Jim Bennon

[Ernie Martin]

Jim, some may miss this post because of the thread title (Oxygen). Consider putting it in a different or new thread under Pressurization. Also, in one post the combustion heater came back as repairable but in the next post as non-repairable; which is it?

Ernie Martin