Steel HP tank 3500 vs 3442???

[BoneCrusher]

I have read alot where Steel HP tanks changed from a rating of 3500 that used a 7/8UNF thread that required the DIN valve to a rating of 3442 with a 3/4NPS tread that could use a valve convertible for DIN/Yoke.

Does anyone know when this happened? Are only 3/4NPS (3442 rating) only being made since then?

Or, do I have this completely screwed up!

 

[Puffer Fish]

Not sure of all the details, but the current 3,442 psi tanks are all the chrome Moly steel ones...much lighter and with far better buoyancy.

I think the pressure difference is silly, but if it allowed them to use the convertable valves (which I have on all of mine)... then it is somewhat understandable....still silly, but understandable.

Using Yoke with them, by the way, is asking for an o-ring blow out...

 

[mike_s]

the big difference I've seen in them is the amount of negative buoyancy in the 3500's compared to the 3442. ((which is what Puffer's talking about with the "far better buoyancy".

go look at some of the old HP100's that were 3500 psi, they'd be -14 pounds negative when full.

yeah the valve difference is big also, but I've never used my convertible valves with the yoke in.

 

[DA Aquamaster]

The choice of valves was purely a Sherwood choice with their "genesis" tanks. The DOT has never specified that you need a certain valve or thread at 3500 psi versus 3442 and the 3/4" thread is more than strong enough. Initially I think they sold a lot 7/8" valves with their tanks in the same way Sony sold a lot of Betamax recorders. But they have also pretty much gone the way of the Beta format (or VHS for that matter).

I think the 3442 psi service pressure to stay under the 3500psi "high pressure" definition is pretty stupid and that was again a Sherwood definition, not a DOT definition - DOT would consider 1800 psi to be "high pressure", so all scuba tansk are "high pressure."

Purists will still call 3500 psi tanks "HP" tanks and 3442 psi tanks something else, but for all practical purposes and for general use to distinguish them from 2250 psi/2475 psi and 2400 psi/2640 psi "LP" tanks it makes sense to call them both HP tanks.

 

[BoneCrusher]

So, is it safe to say, if I am looking at used tanks, it would me better to get 3442 tanks than outdated 3500 tanks? It sounds like the 3500 tanks are becoming a thing of the past, due to their bouyancy characteristics and valve restrictions.

 

[drdaddy]

So, is it safe to say, if I am looking at used tanks, it would me better to get 3442 tanks than outdated 3500 tanks? It sounds like the 3500 tanks are becoming a thing of the past, due to their bouyancy characteristics and valve restrictions.

Years ago I began with Aluminum 80s and a yoke. When they got emptier, they would float. I got HP steel 3442s, 80s and then 100s. I love them. They all have convertable valves that would take DIN, but I continue with yoke as all of my son and I (and most of my friends that I loan a tank to) use yokes. When I switched to steel I took weight off my weightbelt and when they are empty they still are negative buoyant (don't float when empty).

The steel HP 3442 are the only tanks being sold around here.

 

[Rainer]

So, is it safe to say, if I am looking at used tanks, it would me better to get 3442 tanks than outdated 3500 tanks? It sounds like the 3500 tanks are becoming a thing of the past, due to their bouyancy characteristics and valve restrictions.

Having a convertible valve just doesn't matter to me (all DIN).

I have some 3442 HPs and some 3500 HPs. I like both. If you plan to double some up, the newer, lighter ones are nicer. If you're using them as singles, in cold water, having the extra neg buoyancy on your back isn't a bad thing; it has to be carried somewhere. The 3500 cylinders I have are -3 or -4 compared to the 3442 PSTs.

 

[Mitten Diver]

Mike,

I have 2 HP3500 PST tanks and 2 E8 3442 tanks. The 3500's were my original tanks didn't have the 3442 until about maybe 5 years or so ago. I would have bought 2 more of the HP 3500's if they were available at the time. Instead I ended up with the E8-130's. I was a little nervous at first about buying such a big tank, but couldn't be happier now.

The one difference between the two tanks valves is that the valve on my PST tanks let my din reg seat all the way inside the valve where the E8 has a shorter thread that only allows me to thread the din in about 85% of the way. Not a problem though as the oring is still captured in the valve and the valve is still tight on the tank.

 

[micklock]

I have some 3500 hp 80's, original hydro 1998 that are hot dipped galvinized. I've seen older tanks at the dive shop that were cold rolled with a smooth surface and very heavy, are the Worthingtons made today lighter than the ones I have?

 

[mike_s]

So, is it safe to say, if I am looking at used tanks, it would me better to get 3442 tanks than outdated 3500 tanks? It sounds like the 3500 tanks are becoming a thing of the past, due to their bouyancy characteristics and valve restrictions.

it depends on what your diving needs are....

for example, if you're diving a drysuit or a 7mm, you might want that tank that is more negative to offset the extra lift of that suit..