Doubles handle = manifold?

[northernone]

Saw some concern regarding lifting doubles by their manifold bar.

What's your experience in this? Best practice? Unnecessary concern? Something we've not thought about and are simply lucky?

Cameron

 

[KevinNM]

I don't think I've seen anyone pick it up by the manifold. I lift it by the valves or by bear-hugging the tanks when it isn't on the backplate. But the manifold is really strong.

 

[heison]

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.

 

[tomfcrist]

It depends a lot on the doubles...80’s, 72’s, 100’s??? Sure. 108’s, 120’s, 121’s....is rather get a Sherpa to lift them...lol

 

[oldschoolto]

Lifting up the full weight with one hand in the middle is not a very good idea.. Grabbing at the valve to tilt them up is not going to hurt anything.. I think its always been a common sense thing..

But, I've seen divers pull their tank/BC out from the bed of a pickup by the hoses...

Jim...

 

[broncobowsher]

So if you grab the manifold where it attaches to the tanks, right at the valves. Use two hands, one at each valve, how is this any different then picking up a single tank by the valve? You are just doing two at the same time. They are banded together, right? Are you trying to manhandle tanks that are not banded together and only connected by the manifold?

There are a lot of open ended questions about the questionable question that was asked. I can't vote, too many unanswered variables. In some cases it is the preferred method, in other cases it is the worst choice. Two point lift? Single point lift? Single point at one valve? Single point centered on manifold?

Much like jacking up a car there are a lot of places you can put a jack. Many of which are perfectly good places. In some situations one spot may be better than another. But move that jack point just a couple inches to a slightly different spot and you can just about total out a car. A quick glance and it looks exactly the same as a good spot.

 

[northernone]

So if you grab the manifold where it attaches to the tanks, right at the valves. Use two hands, one at each valve, how is this any different then picking up a single tank by the valve? You are just doing two at the same time. They are banded together, right? Are you trying to manhandle tanks that are not banded together and only connected by the manifold?

There are a lot of open ended questions about the questionable question that was asked. I can't vote, too many unanswered variables. In some cases it is the preferred method, in other cases it is the worst choice. Two point lift? Single point lift? Single point at one valve? Single point centered on manifold?

Much like jacking up a car there are a lot of places you can put a jack. Many of which are perfectly good places. In some situations one spot may be better than another. But move that jack point just a couple inches to a slightly different spot and you can just about total out a car. A quick glance and it looks exactly the same as a good spot.

Good clarification points! Thanks.

I had thought sensible options and a standard set of banded doubles.

That is likely two hands. And presumably balanced for easy of carry.

Or one hand for the strong among us, or those with small doubles. Centered for balance in that case too.

I had a pair of lp131 (now sidemount tanks) those aren't getting carried single handedly (or any way) .

Cameron

 

[Caveeagle]

I consider the term "manifold" to mean the assembly of two valves with a cross over bar. So lifting a set of doubles "by the manifold" includes a lot of possible variations.

Lifting a heavy set from the very center of the cross bar or Iso valve seems like a worst possible scenario, be even that... I really double would be a problem.

Regarding "seeing all sorts of bent manifolds at hydro time". ... boy that's sure some annecdotal analysis. How many of those fell off a bench? Or got dropped, or set down hard out of square? Both scenarios much more likely to bent a manifold out of square.

 

[TrimixToo]

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.

 

[Caveeagle]

@TrimixToo

I will add to complication this by mentioning that two of my double sets are OMS manifolds with captured o rings. So there is no way lifting from the cross over can increase load on the o-ring.