Doubles handle = manifold?

[northernone]

My first thoughts were: "I think it's hard to hurt the metal by lifting doubles (even LP125s) in mid-manifold. Brass is pretty strong. If there's any real risk to this, it seems more likely that it would come from O-ring deflection and the possible acceleration of O-ring failure."

But that's just yet another opinion on ScubaBoard, so I thought to myself:

"Self, wouldn't it be interesting to know how much the manifold deflects when you lift it in the center"?

Into the basement I go, to fetch the dial indicator!

Drat and double drat! The rods on the magnetic base do not reach from the side of the tank to the manifold in any orientation. Hmmm. What to do? Ah! Two sets of Vise Grips to the rescue! A small set of VGs to clamp to the band spacer, and a large set of VGs to clamp to the small set. The mag base on the indicator is stable enough on the large VG to get a reading. Eureka!

I place it all on a set of doubles, and it's stable enough to try. Excellent! I even have a set of LP112s and LP108s side by side, one with a Blue Steel manifold and the other with an OMS "captured O-ring" manifold, so I can try both styles. Ready to go! Or, so I thought...

Have ye ever tried to read a dial indicator with a vertical face when it's below you and you're trying to life doubles one-handed, Lassies and Laddies? It Cannot Be Done. OK, so I could have rigged a mirror. And Superman would have no problem. Hell, maybe I'm just a wimp. But since Superman isn't handy and rigging a mirror is getting a bit beyond the pale, it's SuperSpouse to the rescue!!! Flashlight in hand to brightly illuminate the face of the DI, she reports that the manifold on both sets deflects little enough that it does not move the needle enough to see it move as I lift each set, one-handed, in the center. That means neither one deflects anywhere near a thousandth of an inch when lifted in the center; in fact, less than .0005" and probably less than half of that since the DI has a 2" face and it's easy to read.

I was a bit surprised. I'd expected it to move around a *little*, at least. But if I have less than .001" of deflection, I am pretty sure that I am not hurting the brass at all. Further, it leads me to expect that the O-rings are not being disturbed enough in their glands to come to any harm. An engineer might point out the error of my ways, if there is one, I suppose. (And if any are reading, and my conclusions are in error, please chime in!) I don't think it's worth doing again with a tenths-reading DI.

And yes, before someone asks, both sets were full. Of 18/38, if it matters. I'll confess, too, that I carry two sets by the manifolds this way from time to time. It's easier when you're balance from side to side, after all. But now I feel a lot better about it and, to be honest, I didn't feel all that bad about it before tonight.

Superb. Thank you for taking time for this.

 

[JamesBon92007]

I'll admit that I've lifted my steel 50s by the manifold but only to move them a foot or two, and it was with two hands next to each tank. My set had a handle on the side and that's how I carried them.

I have a set of steel 72s but it's a Mickey Mouse setup that attaches to the existing valves and there's no way to pick it up by the crossover without breaking it.

 

[Caveeagle]

I'll admit that I've lifted my steel 50s by the manifold but only to move them a foot or two, and it was with two hands next to each tank. My set had a handle on the side and that's how I carried them.

I have a set of steel 72s but it's a Mickey Mouse setup that attaches to the existing valves and there's no way to pick it up by the crossover without breaking it.

Haha. ...steel 50s. That's cute.

But seriously, I've been lifting double 95s, 104s and 108s. ..(with strong fills)for years.

I just don't see how this is an issue.

 

[oldschoolto]

I'll admit that I've lifted my steel 50s by the manifold but only to move them a foot or two, and it was with two hands next to each tank. My set had a handle on the side and that's how I carried them.

I have a set of steel 72s but it's a Mickey Mouse setup that attaches to the existing valves and there's no way to pick it up by the crossover without breaking it.

Another guy with old school 72's and a cheater bar doubles... I love mine...

Jim...

 

[Akimbo]

It depends on the manifold. OMS used to make an isolation manifold that used DIN fittings on both sides of the isolation valve and on the post valves that was more than strong enough. US Divers (now Aqua Lung) made a one-piece double manifold for the military that was also very strong.

In an ideal world, I would like to see an isolation manifold made from a one-piece forging like the image above. IMO, it is better to have a fixed center-center distance and shim the bands than attempt to make the manifold width adjustable.

It is very easy to force cylinders into very precise center-center spacing with a couple of plastic spacers.

The valve-down doubles protector I use has a handle integrated into the design that works pretty well.

 

[rjack321]

My first thoughts were: "I think it's hard to hurt the metal by lifting doubles (even LP125s) in mid-manifold. Brass is pretty strong. If there's any real risk to this, it seems more likely that it would come from O-ring deflection and the possible acceleration of O-ring failure."

But that's just yet another opinion on ScubaBoard, so I thought to myself:

"Self, wouldn't it be interesting to know how much the manifold deflects when you lift it in the center"?

Into the basement I go, to fetch the dial indicator!

Drat and double drat! The rods on the magnetic base do not reach from the side of the tank to the manifold in any orientation. Hmmm. What to do? Ah! Two sets of Vise Grips to the rescue! A small set of VGs to clamp to the band spacer, and a large set of VGs to clamp to the small set. The mag base on the indicator is stable enough on the large VG to get a reading. Eureka!

I place it all on a set of doubles, and it's stable enough to try. Excellent! I even have a set of LP112s and LP108s side by side, one with a Blue Steel manifold and the other with an OMS "captured O-ring" manifold, so I can try both styles. Ready to go! Or, so I thought...

Have ye ever tried to read a dial indicator with a vertical face when it's below you and you're trying to life doubles one-handed, Lassies and Laddies? It Cannot Be Done. OK, so I could have rigged a mirror. And Superman would have no problem. Hell, maybe I'm just a wimp. But since Superman isn't handy and rigging a mirror is getting a bit beyond the pale, it's SuperSpouse to the rescue!!! Flashlight in hand to brightly illuminate the face of the DI, she reports that the manifold on both sets deflects little enough that it does not move the needle enough to see it move as I lift each set, one-handed, in the center. That means neither one deflects anywhere near a thousandth of an inch when lifted in the center; in fact, less than .0005" and probably less than half of that since the DI has a 2" face and it's easy to read.

I was a bit surprised. I'd expected it to move around a *little*, at least. But if I have less than .001" of deflection, I am pretty sure that I am not hurting the brass at all. Further, it leads me to expect that the O-rings are not being disturbed enough in their glands to come to any harm. An engineer might point out the error of my ways, if there is one, I suppose. (And if any are reading, and my conclusions are in error, please chime in!) I don't think it's worth doing again with a tenths-reading DI.

And yes, before someone asks, both sets were full. Of 18/38, if it matters. I'll confess, too, that I carry two sets by the manifolds this way from time to time. It's easier when you're balance from side to side, after all. But now I feel a lot better about it and, to be honest, I didn't feel all that bad about it before tonight.

Nice test!

I have seen more than one bent crossbar. These are barrel oring sealing cross bars (not the OMS face sealing design) and the left and right threads aren't aligned anymore. They were never dropped (not my tanks but I believe the owner)

So the real inquiry is "how did that happen?" My suspicion is that the tanks were bumped out of alignment while the bands were loose. The tanks have a lot of leverage in the soft brass.

 

[lowviz]

...//... So the real inquiry is "how did that happen?" My suspicion is that the tanks were bumped out of alignment while the bands were loose. ...

I saw it happen years ago at Dutch Springs. A guy got a fill and then swung the set down and one tank hit first. That meant that the bands and the manifold had to decelerate the second tank. No go, gentle hissing...

I'll lift my double 100's by the manifold but it is a gentle acceleration to get them off the ground and a gentle landing on both tanks.

 

[ajduplessis]

I often see tanks for annual VIP with bent manifold bar, don't want to find out whether it's caused by lifting by manifold. I would bear hug mine.

IMO bent manifolds are caused by impact putting them down at an angle without proper control. I have seen this happen a couple of times.

 

[lowviz]

Agree completely.

To be explicit: You can damage a manifold by holding each tank/cylinder by its neck while dropping the set at an angle that makes one tank hit first. Never touched the manifold...

 

[rjack321]

Agree completely.

To be explicit: You can damage a manifold by holding each tank/cylinder by its neck while dropping the set at an angle that makes one tank hit first. Never touched the manifold...

I believe you but have not seen this happen with modern bands.