Spare Air ? Fact or Fiction

[Bryan]

As most of you know 99.9% of the dive boat operators will not allow you to dive without a pressure gauge and a secondary air source on your double hose.

Many of you are using Dacor Valves with the HP port that allows you to use a pressure gague. Or a Trieste and I 'm still working on the banjo fittings!!!

When it comes to the required safe 2nd/Octopus,if you have a hookah port you can use an adaptor and attach one. If you don't have a hookah port you then have to use a pony bottle, doubles with a manifold that allows you to attach a seperate regulator. Or perhaps a Spare Air setup
www.spareair.com/

These have been around for years but I have no direct hand knowlege of anyone actually using one in an out of air situation. Will dive operators accept one as your only source of sharing air? I"ve heard good and bad about them. Please share your thoughts an or experience with the device.

[JES]

Bryan,

I personally own one but have never had to use it.

I'm not sure what the dive operators will or will not accept but I have heard that TSA may or may not allow you to travel with one. This has been discussed on other Scuba websites at length.

I'm sure that you noticed the stories of the divers who have used their Spare Air on the website you included - www.spareair.com/product/storyby.htm#savedmylife

On an informational note: The Navy & Marine Corps issued the Spare Air to its helicopter aircrew and it was called the HEED (Helicopter Emergency Escape Device). The HEED was carried as a part of the aircrew’s survival equipment and did in fact save many lives from many in-water mishaps. However, the HEED was only rated to 1800 psi and was eventually replaced by the current emergency breathing device called the HABD (Helicopter Aircrew Breathing Device). The HABD is manufactured by US Divers and has a separate 1st (with a small SPG) on the cylinder connected by a hose to a 2nd stage and it is rated for 3000 psi.

Regards,

Joe

[JES]

Here is a link to a picture of the HABD.

www.specwargear.com/images/survivalgear-HABD-1.jpg

[Terry]

Bryan,
I also own a Spare Air (3.0) and fortunately so far have never had to use it. I have on many occasions during a dive pulled it out of the holster and tested it, and have always been well satisfied with it's performance. I do quite a few solo dives and it's always nice to know that I have some form of backup system to get me safely to the surface should the need arise. Safe Diving To You! Terry Stevens

[Deleted]

I avoid the Spare Air, simply not enough air, and of course, not "vintage". I picked up a couple of USD Survivair tanks on ebay, fitted them with "taco clips" and D rings, and use a very vintage Calypso or Conshelf for my reserve. Gives 2X the gas as a Spare air, maybe more + a decent regulator. I also use the Hookah port on my DHs to inflate a USD 70s vintage horsecollar. Have a couple of Sherwood Selpac doubles manifolds that permit me to use the single hose right on the manifold. Anyone out there also had trouble with the unions on USD doubles manifolds leaking and if so how do you fix them? John

[seakrakken]

I'm not trying to be funny but, Aqualung did fix that problem with the leaking unions on the doubles manifold. They made a single piece manifold which eliminated all those headaches. Yes it is vintage and yes they were very proud of them. I have one on Ebay right now for a whopping $100. Mind you though it is NIB. These retail for nearly$500. For anyone who may not know what one looks like this is a link to the Ebay Auction in progress.
cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=7117738964&ssPageName=STRK:MESE:IT

[Deleted]

What is the procedure for attaching the one piece manifold to tanks? I have a couple of Sportsways as well as others that have O rings at the unions that seem to be quite an improvement over the USD design. John

[seakrakken]

Well it's not unlike installing a doubles manifold that's multi-piece. Except in this case the tanks screw onto the manifold not the manifold onto the tank, being carefull not to twist the manifold while screwing on the tanks. Once they're on then tighten up the tank bands.
Below I'm posting a pic of the manifold I mentioned earlier and a page from the Aqualung Parts Catalog which gives a good parts breakdown drawing.

[Deleted]

I assume that after one tank is on that possibly the unit is placed on a flat surface and the second tank is tightened with a strap wrench or is hand tight sufficient?? Am following the auction and have "discovered" the hex insert in the reserve side of a USD manifold that I have been told can help sealing if adjusted properly. Thanks for the diagram. John

[seakrakken]

You presume correctly that a strap wrench, wrench and table. would be involved. I have not installed one of these before. I'm sure that rndboulder is very familiar with the procedure because he uses them for his new C-Shell. This thing is realy cool. If I could scrounge up the funds for it I would get one but, I've got too many irons in the fire. I'll paste a link to his site below.
www.flashbackscuba.com/products/cshell.html

[SeaRat]

I'm not at all sure you guys are correct about the strap wrench. Why do you need to tighten it tighter than hand tight? It has an O-ring fitting, and really does not need to be on any tighter than getting the O-ring into position.

The tanks that needed to have the wrenches tighten the valves were those with 1/2 inch tapered threads, and used teflon tape and pressure to make the seal. This is where the older USD valves, with the brass mating surfaces, came in handy, as there was a need for a wrench on those valves. This was not a problem when the tank was steel, and the valve was brass.

Current valves, with O-ring seals on three-quarters inch threads, do not need to be wrenched tight. They only need to be hand tight. Nothing aggrevates me more than to get my tank & valve back from the LDS and not be able to get the valve off by hand. That, to me, means that the threads could be compromised on the tank. The tank is aluminum alloy, and the valve is brass. I think they are either about the same hardness, or that the brass is slightly harder than the aluminum. If you use a wrench on the valve or tank, you could potentially damage the threads.

By the way, the brass mating surfaces on the twin tank USD manifold usually only need to be tightened more to stop leaks. Occasionally, perhaps they have been either damaged or there's some corrosion that needs to be taken off, either chemically (preferably), or with steel wool lightly brushed against the brass. I normally tighten the connection nuts with a wrench only as tight as I feel is appropriate, then put some air in them and take them to the pool for a leak check. If they leak (I had one side of my twins recently leak), I let all the air out (any work must be done at zero pressure (guage), then tighten the nut again with a large wrench. I am still leary about over-tightening even this connection, as it is possible to split the brass fittings and ruin the valve.

John

[seakrakken]

Thanks SeaRat! I was not aware that hand tight was enough for aluminum tanks. Unfortunately, I'm guilty of applying Blue Torque to everything. (Torque it 'till your Blue in the face!)

[SeaRat]

Hand tight is all it takes to mate a valve to any scuba tank, if the tank uses an O-ring for a seal. This is true for either aluminum or steel tanks. It is the captured O-ring that makes the seal, and not the tightness of the threads. You put pressure into the tank, and there is no way you can move the valve, even if hand tight with no pressure.

Now this discussion is making me wonder about the recall of the Luxfer aluminum tanks, and whether over-torquing the tank valve threads could have been a source for their problems.

John

[Deleted]

Local Hydro shop tells me the O ring valves should be torqued to 40 or so ft/lbs. I agree that air pressure does the sealing. I have seen several tanks that were holding air OK whose valves could be screwed out by hand when pressure was relieved. BTW, the first Al tank that blew was a Kidde. They dealt with the problem as they say it by making the necks heavier. I read somewhere that lead in the alloy "migrates" over time causing the defects. Also that even after a crack is evident on eddy testing that it takes 6-9 yrs before there is an overt failure. With doubles I guess that the bands keep the threads from backing out if all pressure is relieved. Anyone have any experience with USN round bottom tanks(doubles) sometimes called "90s"? I have a set I cant get hydo on as they dont have a DOT stamp. John

[John Ratliff]

Thanks for the info on the torquing of the valves. I still don't want to do it on mine.

Concerning the Navy 90s, these cannot be hydroed. They were made for the US Navy for one-time use, and were made before the newer aluminum was developed. They have an old process, in which both the neck and the bottom were put together differently than today's tanks (I think there is actually a plug in the bottom to form the rounded area).

I saw some in the 1980s that had been sold to a local high school as government surplus, and to be used to practice welding on in their shop. Someone recognized them as former scuba tanks, and brought them to the LDS. The LDS asked me about them, and I told them to drill the cylinders so as to make them unusable. I don't believe there are any left in active inventory in the Navy, as they would have switched to the newer designs by now. These tanks (the old Navy 90s) could be hazardous to fill at this time.

John