Tiny Doubles Gas Capacity

[Lopez116]

Thanks everyone for your input and advice.

 

[Lopez116]

ok, it really depends on the dives your want to pull of with the twin set. As someone else mentioned above they would work best for one long dive. I'm sure you can do 2 dives with them granted the deeps aren't to deep. I've seen plenty of people on dive boats use a single 100 for a 60ft dive and then a shallow reef at ~30 to 20 ft. and get reasonably good bottom times.

Cost wise its a different story, getting your hands on single AL80s is pretty easy and relatively inexpensive especially if you get them used. the double 50s will be notably more pricey new or used, plus all the extra hardware. that being said if you are planning on doing solo dives weather truly alone or even with "same ocean buddies" I would consider a set of doubles.

Question, have you looked at some of your past dives you've done on open circuit and tried to calculate if the twin 50s would be a god choice as far as having enough gas is concerned?

Another thing I would consider looking at is weather your dive shop would knows how to fill and certify low pressure steels, I've had the problem here where I live that the dives shops don't understand the 2400 + rating. Not knowing how to hydro the tank for it as well as thinking that 2400 is the max pressure with the + sign (Should be 2640 psi). IF they do at least know this, then I would also ask the person that normally fills the tanks for you at the fill station if he's ok with putting a bit more air in them. This is however normally not a common practice out side of cave diving communities so you might get looked at funny by the shop guy and get an out right NO. if they are ok with it then you got your self a pretty good situation to be diving the twin 50s. Make sure to stack the burst disks on the tanks if you do intend to over fill them though, a real "cave fill" as they're called can be up words of 4000 psi some times.

I have the twin steel 50's already here from when I came over the U.S., but they've never been dived (long story). So I'd be looking at a manifold and bands only.

My SAC rate is good. I prefer one long dive over two shorter ones and on an AL 80 filled to 3200-3300, my usual shore dive is around 90 min (max depth of about 60' with another 30 min in the shallows around 20'-30'. That is essentially the profile I'd stick with, but have slightly more gas and redundancy.

I didn't think to ask if my shop was familiar with steels or what they'd fill them to. I will talk to them tomorrow most likely and see what they say. Thanks!

 

[Lopez116]

small island on the caribbean I would use aluminum bottles to not have to worry about rust. The 50's are undoubtedly better if and only if you can get 3600psi fills on them, but if I was in the caribbean I would prioritize aluminum bottles.

Did not consider corrosion, but that's a good point. EVERYTHING corrodes here!

 

[ermaclob]

I have the twin steel 50's already here from when I came over the U.S., but they've never been dived (long story). So I'd be looking at a manifold and bands only.

My SAC rate is good. I prefer one long dive over two shorter ones and on an AL 80 filled to 3200-3300, my usual shore dive is around 90 min (max depth of about 60' with another 30 min in the shallows around 20'-30'. That is essentially the profile I'd stick with, but have slightly more gas and redundancy.

I didn't think to ask if my shop was familiar with steels or what they'd fill them to. I will talk to them tomorrow most likely and see what they say. Thanks!

oh dude. if you have the 50s already then I would slap them together just for fun at that point. That's just my 0.02 cents. the bands would be the only item to look for, you can find manifolds everywhere. idk if you can get things ordered from the USA but Dive gear express sells the bands. 5.5 inch for the LP50s. Though maybe you can find these cheaper used somewhere else.

DGX Premium Doubles Bands Set w/Bolts

These DGX premium quality Heavy-Duty Double Tank Bands offer standard 8.5-inch center to center manifold spacing, so no special manifold is required. Set of two bands with bolt kits.

www.divegearexpress.com

They also sell this unbranded manifold for $99. i recently bought a set and they are pretty good quality. RIP old beat up OMS manifold. price wise for a brand new set of valves I don't think you can beat this. Unless the shipping for you is to much.

DGX Gears Premium Dual-Outlet Manifold with Isolator

The manifold consists of left and right DGX Premium modular valves with an isolation crossbar offering 8.5-inch adjustable center-to-center spacing that perfectly fits any diameter scuba cylinders using standard tank bands.

www.divegearexpress.com

 

[Lopez116]

oh dude. if you have the 50s already then I would slap them together just for fun at that point. That's just my 0.02 cents. the bands would be the only item to look for, you can find manifolds everywhere. idk if you can get things ordered from the USA but Dive gear express sells the bands. 5.5 inch for the LP50s. Though maybe you can find these cheaper used somewhere else.

DGX Premium Doubles Bands Set w/Bolts

These DGX premium quality Heavy-Duty Double Tank Bands offer standard 8.5-inch center to center manifold spacing, so no special manifold is required. Set of two bands with bolt kits.

www.divegearexpress.com

They also sell this unbranded manifold for $99. i recently bought a set and they are pretty good quality. RIP old beat up OMS manifold. price wise for a brand new set of valves I don't think you can beat this. Unless the shipping for you is to much.

DGX Gears Premium Dual-Outlet Manifold with Isolator

The manifold consists of left and right DGX Premium modular valves with an isolation crossbar offering 8.5-inch adjustable center-to-center spacing that perfectly fits any diameter scuba cylinders using standard tank bands.

www.divegearexpress.com

Gotcha! True. Might as well play with them.

Sadly, by the time we ship things here and pay duty, the total cost is about 2x the cost you pay online. I saw those DGX manifolds. They're apparently on backorder until at least Jan (According to the rep). I have relatives coming here in Dec., so may pick some up and have them come in with them!

 

[Scared Silly]

Makes me nervous....
You can greatly overfill the steel 50s, but beware of the AL any size.

Those 3200psi-3400psi fills are probably hot/warm fills that cool down to 2900psi - 3100 psi. We regularly filled to 3300 psi and they cooled to 3000psi.

 

[halocline]

If you are used to diving with one AL80 in the warm water of the caribbean, you might find yourself pretty overweighted with the 50 doubles. I assume the tanks are negative, and you can add about 8lbs more negative for the bands and manifold. So unless you use 10-12lbs at least with your AL80, be prepared to sink like a stone with steel doubles, even small ones. I used to use LP72 doubles (which are slightly positive empty) with a 3 mil wetsuit and I was always heavy. I switched to AL80 doubles and that helped considerably, but I still used them with no weight and I was overweighted in a 3 mil. Same wetsuit, single AL80 I use 6-8 lbs depending on the day.

From what I've read, you might be best served by sticking with your AL80 and slinging an AL30 or 40 as a bailout bottle. You could use it to extend your dive (don't tell anyone you heard that from me, hehe) and it would provide PLENTY of redundancy for NDL, OW diving. Way more than necessary, actually. Just a 19cft pony would certainly suffice as an emergency air source for a solo dive.

Just keep in mind that there is a very good reason that diving with multiple tanks and/or extending dive range via extra bottles is considered technical diving and has lots of specialized training. It feels nice to have an extra air source, but anything that results in greater complexity and longer bottom times does carry some increased risk.

 

[Julius SCHMIDT]

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