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Oxygen Systems at Clubs
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Patrick (LS6-b EH)
May 6, 2022, 1:50:10 AM5/6/22
to
Hey friends, our club is thinking about a O2 system and would like some feedback on other systems - that you're proud of.
- trailer-based
- fixed filling
- pump vs. filled bottles
Right now rely either on the generosity of a member, or a O2 cart that moves around the region and isn't always available.
Thanks for your constructive input.
Patrick
Cu Nim
- trailer-based
- fixed filling
- pump vs. filled bottles
Right now rely either on the generosity of a member, or a O2 cart that moves around the region and isn't always available.
Thanks for your constructive input.
Patrick
Cu Nim
George Haeh
May 6, 2022, 12:43:44 PM5/6/22
to
Hey Patrick,
I dropped off the ASC O2 trailer and hose box at CuNim a couple days ago. It's looking for a pull to the NATS.
You're welcome to have a look.
The tubing was replaced with hoses aka pigtails.
Somehow a 12" hose ordered for 12" between cylinders ends up 17.75" long when fittings are added which makes problems with minimum bend radius.
But it seems manufacturers don't make up hoses shorter than 12".
The cylinders are really heavy; so you need a trailer chassis up to the job.
I dropped off the ASC O2 trailer and hose box at CuNim a couple days ago. It's looking for a pull to the NATS.
You're welcome to have a look.
The tubing was replaced with hoses aka pigtails.
Somehow a 12" hose ordered for 12" between cylinders ends up 17.75" long when fittings are added which makes problems with minimum bend radius.
But it seems manufacturers don't make up hoses shorter than 12".
The cylinders are really heavy; so you need a trailer chassis up to the job.
Mark Mocho
May 6, 2022, 1:24:37 PM5/6/22
to
I've set up several Oxygen refill stations/carts over the years, starting with our hang gliding club in 1992. I think the easiest is a single cylinder with a simple transfill adapter from Mountain High. However, the single cylinder option, while relatively inexpensive, drains quickly after multiple fills, resulting in much less pressure in the target cylinder. A better solution is a multiple cylinder cascade system that allows for lower pressure cylinders in the cascade to provide the bulk gas (by volume) which is then topped off by the cylinders containing higher pressure. For example, three cylinders in the cascade might contain 800, 1,400 and 2,000 psi after several refills. You bring in a cylinder from your glider with 700 psi remaining. First you connect it to the lowest pressure cylinder (800 psi) and bring it up to an equal pressure. Then, you close the valve on the 800 psi cylinder, open the 1,400 psi bottle and top off. Finally you close the second cylinder valve and open the 2,000 psi valve and bring your cylinder to the highest pressure possible. Then you close all the valves and bleed the O2 from the fill line and disconnect your cylinder. Typically, the three cascade cylinders might now show 750, 1,200 and 1,900 psi, with yours also at 1,900 psi.
There will always be some wasted pressure, as it seems that everyone wants to refill as soon as their glider cylinder pressure drops below 1,000 psi' This means that the lowest cylinder in the cascade gets replaced to make room for a new high pressure cylinder while still containing half its contents.
Mountain High sells all of the required transfill hose kits with end connections, bleed valves and pressure gauges. They can also outfit you with connections to set up a multiple cylinder cascade. (https://www.mhoxygen.com/product-category/ground-support-equipment/?msclkid=2577c5b9cd5e11ec8312274cbcf435f3) I consider three cylinders to be the minimum needed. Four, or even five cylinders in the cascade are much more efficient at keeping the top pressure as high as possible, but at a higher expense if you are buying or leasing the cylinders. Also, the cylinders are very heavy (300 lbs.), and anything over three cylinders is a bear to move around.
For a trailer, I suggest an inexpensive flat trailer from a supplier like Harbor Freight (https://www.harborfreight.com/automotive/trailers-towing/1090-lb-capacity-40-12-in-x-48-in-utility-trailer-62665.html) You will need to fabricate a cradle system to securely hold the cylinders. You definitely don't want them coming loose and falling off while hauling it around the airport. "MythBusters" did a great experiment where they knocked the valve off a pressurized cylinder and watched the bottle blow through a concrete barrier.
Make sure the cradle you build has some leeway to handle variations in cylinder size. Most are pretty close in diameter, but length can vary by several inches. "Aviators Breathing Oxygen" is preferred for the main cylinders, as their capacity is usually higher (335 cu. ft. vs, 300 cu. ft.) and they are also generally filled to 2,200 psi. Welding Oxygen cylinders are normally 2,000 psi, And, in spite of what some people still believe, there is absolutely no difference between Aviators, Welding or Medical oxygen. Except for the price, which is determined by the expected liability (read: lawyers) involved. Medical Oxygen falls under Food and Drug Administration (FDA) rules, and requires a prescription. Welding and Aviators O2 are under Department of Transportation (DOT) protocols.
You will also probably need a set of adapters to go from the CGA-540 fitting on the end of the refill line to accommodate other fill valve systems typically found in gliders. The most common is a "Schrader" valve, which looks like the fitting on a car tire (but isn't), a European style DIN-477 valve or a CGA-870 fitting. (Also referred to as a "Post type," "Medical," or "Puritan-Bennett.) You may also need a refill hose extension, as some gliders (notably Schempp-Hirth) have their onboard cylinders buried deep in the fuselage and are difficult to refill and worse to try to remove.
You mentioned a pump as an option. From what I understand (having little experience with industrial pressure concentrators) they require an air compressor to power the piston pump and a source of oxygen (meaning a cylinder. The one I have used is from Hydraulics International, costs about $5,000 and, with 175 psi. air pressure for the pump, can raise the available cylinder pressure about 50%. This means that you can increase the 2,000 psi in your fill cylinder to about 3,000 psi in your target cylinder. This necessarily implies some risk, as 3,000 psi is above the rated capacity of most commercially available portable cylinders. Personally, I would discourage their use.
There will always be some wasted pressure, as it seems that everyone wants to refill as soon as their glider cylinder pressure drops below 1,000 psi' This means that the lowest cylinder in the cascade gets replaced to make room for a new high pressure cylinder while still containing half its contents.
Mountain High sells all of the required transfill hose kits with end connections, bleed valves and pressure gauges. They can also outfit you with connections to set up a multiple cylinder cascade. (https://www.mhoxygen.com/product-category/ground-support-equipment/?msclkid=2577c5b9cd5e11ec8312274cbcf435f3) I consider three cylinders to be the minimum needed. Four, or even five cylinders in the cascade are much more efficient at keeping the top pressure as high as possible, but at a higher expense if you are buying or leasing the cylinders. Also, the cylinders are very heavy (300 lbs.), and anything over three cylinders is a bear to move around.
For a trailer, I suggest an inexpensive flat trailer from a supplier like Harbor Freight (https://www.harborfreight.com/automotive/trailers-towing/1090-lb-capacity-40-12-in-x-48-in-utility-trailer-62665.html) You will need to fabricate a cradle system to securely hold the cylinders. You definitely don't want them coming loose and falling off while hauling it around the airport. "MythBusters" did a great experiment where they knocked the valve off a pressurized cylinder and watched the bottle blow through a concrete barrier.
Make sure the cradle you build has some leeway to handle variations in cylinder size. Most are pretty close in diameter, but length can vary by several inches. "Aviators Breathing Oxygen" is preferred for the main cylinders, as their capacity is usually higher (335 cu. ft. vs, 300 cu. ft.) and they are also generally filled to 2,200 psi. Welding Oxygen cylinders are normally 2,000 psi, And, in spite of what some people still believe, there is absolutely no difference between Aviators, Welding or Medical oxygen. Except for the price, which is determined by the expected liability (read: lawyers) involved. Medical Oxygen falls under Food and Drug Administration (FDA) rules, and requires a prescription. Welding and Aviators O2 are under Department of Transportation (DOT) protocols.
You will also probably need a set of adapters to go from the CGA-540 fitting on the end of the refill line to accommodate other fill valve systems typically found in gliders. The most common is a "Schrader" valve, which looks like the fitting on a car tire (but isn't), a European style DIN-477 valve or a CGA-870 fitting. (Also referred to as a "Post type," "Medical," or "Puritan-Bennett.) You may also need a refill hose extension, as some gliders (notably Schempp-Hirth) have their onboard cylinders buried deep in the fuselage and are difficult to refill and worse to try to remove.
You mentioned a pump as an option. From what I understand (having little experience with industrial pressure concentrators) they require an air compressor to power the piston pump and a source of oxygen (meaning a cylinder. The one I have used is from Hydraulics International, costs about $5,000 and, with 175 psi. air pressure for the pump, can raise the available cylinder pressure about 50%. This means that you can increase the 2,000 psi in your fill cylinder to about 3,000 psi in your target cylinder. This necessarily implies some risk, as 3,000 psi is above the rated capacity of most commercially available portable cylinders. Personally, I would discourage their use.
Mark Mocho
May 6, 2022, 1:30:34 PM5/6/22
to
Somehow a 12" hose ordered for 12" between cylinders ends up 17.75" long when fittings are added which makes problems with minimum bend radius.
But it seems manufacturers don't make up hoses shorter than 12".
You CAN get pigtails made smaller, but still too long to fit between cylinders side by side. What I recommend is running the pigtails in an "S" curve. I can send a photo if you are interested. Another option is a small diameter copper line between cylinders, but it is more susceptible to damage, and if it fails, the results can be very dangerous.
But it seems manufacturers don't make up hoses shorter than 12".
Eric Greenwell
May 6, 2022, 3:31:03 PM5/6/22
to
cylinders. Would something like this work?
https://factorysupplyoutlet.com/manifold-rigid-pigtails-cga-346-3000-psig-copper-5-16-in-1-ea-ea/
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications
George Haeh
May 6, 2022, 4:12:11 PM5/6/22
to
Hi Mark,
We perforce S bended the pigtails, but some bends are more cramped than others. Please send photos of your arrangement to George dot Haeh at Gmail dot come.
Which manufacturers will make up shorter pigtails?
We perforce S bended the pigtails, but some bends are more cramped than others. Please send photos of your arrangement to George dot Haeh at Gmail dot come.
Which manufacturers will make up shorter pigtails?
Mark Mocho
May 6, 2022, 4:25:53 PM5/6/22
to
Eric- That's the general idea, but they have to fit the proper nipple and nut needed for a CGA-540 socket on the oxygen cylinders. The ones in your example have a 5/16 NPT fitting- relatively uncommon. Plus, they need to have a socket with the proper seat to seal correctly. And then that fitting has to mate with the CGA-540 fittings. And if you are running three cylinders, you need a couple of "T" fittings, and so on. Easiest method to get what is needed from end to end is to call Eric at Mountain High and have him set up a kit for the application. Lots easier than hunting around the internet and welding supply houses trying to source the individual items, especially for someone that is unfamiliar with the requirements of a transfill system.
I had Matheson Tri-Gas make some shorter pigtails, but if I remember correctly, it took several weeks. And that was before the panicdemic that made oxygen equipment just about unavailable. Cramer-Decker used to ship aluminum cylinders within a couple of days. They are now estimating FIFTY WEEKS!
I had Matheson Tri-Gas make some shorter pigtails, but if I remember correctly, it took several weeks. And that was before the panicdemic that made oxygen equipment just about unavailable. Cramer-Decker used to ship aluminum cylinders within a couple of days. They are now estimating FIFTY WEEKS!
Jay Campbell
May 7, 2022, 9:41:55 AM5/7/22
to
Western Enterprises is a good source for all of your re-fill/transfill needs, but if you are looking for schraeder-type fittings, the regular soaring supply houses have those.
Try going to http://westernenterprises.com/.
You can then select "Pigtail Generator" from the menu on the left and specify material, end fittings, and length. Once this generates a part number, you can order through your favorite welding supplier. All Western products come "cleaned for oxygen service" so no worries about the safety of their products.
Try going to http://westernenterprises.com/.
You can then select "Pigtail Generator" from the menu on the left and specify material, end fittings, and length. Once this generates a part number, you can order through your favorite welding supplier. All Western products come "cleaned for oxygen service" so no worries about the safety of their products.
Richard Pfiffner
May 7, 2022, 11:01:22 AM5/7/22
to
On Saturday, May 7, 2022 at 6:41:55 AM UTC-7, campbe...@gmail.com wrote:
Transfiller equipment.
http://www.craggyaero.com/mh_transfillers.htm
Richard
www.craggyaero.com
Transfiller equipment.
http://www.craggyaero.com/mh_transfillers.htm
Richard
www.craggyaero.com
2G
May 10, 2022, 10:55:32 PM5/10/22
to
https://www.ebay.com/itm/333402663405?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=333402663405&targetid=1263433204774&device=c&mktype=&googleloc=9033822&poi=&campaignid=14859008593&mkgroupid=130497710760&rlsatarget=pla-1263433204774&abcId=9300678&merchantid=6296724&gclid=Cj0KCQjwmuiTBhDoARIsAPiv6L9Cfhkz3yIujGm9Qho5VeBsFLVCOLKg_Xfqm1RtQudi4HNIZ2qYEOoaAm7dEALw_wcB
You need to have a bleed valve because uncoupling the hose from the tank under pressure will damage the O-ring.
Tom
Dan Marotta
May 11, 2022, 1:01:50 PM5/11/22
to
I've been uncoupling my transfill hose for 5 years or so without a bleed
valve and had no problems with o-rings. That said, a bleed valve would
make it easier!
I think the trick to not damaging the o-ring is to release the pressure
very slowly. I loosen the hose very slightly, just until I can hear a
hiss and then let it drain completely. It doesn't take long, but
there's no big blast of O2, either.
Dan
5J
valve and had no problems with o-rings. That said, a bleed valve would
make it easier!
I think the trick to not damaging the o-ring is to release the pressure
very slowly. I loosen the hose very slightly, just until I can hear a
hiss and then let it drain completely. It doesn't take long, but
there's no big blast of O2, either.
Dan
5J
Dan Daly
May 11, 2022, 4:32:19 PM5/11/22
to
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