Negative Buoyancy Tanks

[Lost Yooper]

FHD,

What kind of tanks are you using? This seems a bit odd as most people with LP steels and shell dry suits need a little bit of weight with empty tanks (in the form a V-weight, cannister light, weightbelt). I would have opted for a lift bag rather than double bladders for it's multi use.

With double LP PST 95's, crushed neoprene shell suit, 200g underwear, I need an 8lb V-weight with empty tanks.

Mike

 

[Warhammer]

Originally posted by Tavi
I believe that the 3300 PSI Tank has a DIN valve (anything over 3000 psi does). Is your regulator DIN? If you haven't bought one yet, these are things to keep in mind.
I have a DIN regulator, and a DIN to yoke adapter. I dive steel tanks near home (DIN valves) and use the adapter on vacations (rental aluminum 80's).

So many choices :bonk:

PS. there are no stupid questions :nono:

It depends on the tank. For example a Luxfer S100 is rated at 3300 PSI and comes standard with a yoke fitted valve, whereas the Luxfer S080N is also rated at 3300 PSI and comes standard with a DIN fitted valve. Most yoke valves, and most reg's A-clamp fittings, are rated for 232 BAR which is 3365 PSI. You also have 2 different types of DIN valves, the 232 BAR and the 300 BAR (4351 PSI). What limits you to 3000 PSI on AL80 is the tank, not the valve.

 

[Tavi]

Thanks for straightening me out on that. I've seen the DIN 3300psi tanks. I haven't seen the yoke 3300psi tanks.
I know I have read and been told that anything over 3000psi is DIN.

Another case of repeating someone elses misinformation. :bonk:

 

[Warhammer]

Next time you're in a shop check and see if they any aluminum 100s. If they are Luxfers or Catalinas, then they'll be rated at 3300 PSI and most likely have yoke valves. Those tanks are the only exception to the "over 3000 PSI = DIN" rule that I can think of.

 

[Walter]

I have some Scubapro (Faber) steel slim 72's rated for 3300 (with the 10% overfill) with yokes. When we first started seeing DIN in the US (mid to late 80's) they were on 3500 PSI Genesis steel tanks. For a long time you never saw them on anything else. A DIN is a more secure fitting for high pressure, but I've seen yokes used up to 3800 PSI.

DSSW,

WWW™

 

[Tavi]

Thanks again, I'll be looking for them.

 

[scubabunny]

I've always wondered why people in the states didn't use the NB (neutral bouyant) aluminum 80 tanks. Now I understand..didn't take into account the fresh water...not to mention the COLD water!

Here, we prefer the NB80s, but then again we are diving in warm salt water where most people wear 6-1lbs. Didn't think that the S80s are bouyant in salt water....but not in fresh water.

BTW...when it comes to yoke or DIN fitting for valves, I think it all depends on what your shop orders. We carry both the Catalina C80s and the Luxfer NB80s in yoke fittings, because that is what our customers use. They have a choice in what valve to order with the tanks.