Steel HP tank 3500 vs 3442???

[spectrum]

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!

You have a pretty good handle on it, here are a few more details.

If you stay with apples to apples you are talking about Pressed Steel Tank (PST) brand cylinders. They got Private Branded for USD/Aqualung, Sherwood, Genesis and probably more. Even on those you can usually make out the 'Pst" symbol in the original hydro. They are essentially the same as what went on to be the PST E series cylinder. The changes were going to the common 3/4 pipe thread and shaving a few atmospheres off of the rating to get them under 3500 PSI and into the realm of Yoke connections.

If you find some of these 3500 PSI cylinders and care to dive in a DIN configuration the going price is about half of what an XS Scuba X-series cylinder is selling for. Getting them at that price in hydro/VIP is a good deal.

Pressed steel is for all intents and purposes out of business. Some E7-80 cylinders did surface recently but they are not making much if anything. Meanwhile Worthington introduced a clone of the E series. This is marketed mainly by XS-Scuba as the X series.

Beyond this there are some other cylinders out there notably Faber that are differently proportioned and significantly more negative. I'm not sure if they did 3500 PS versions though.

I bought my E series cylinders in 2005 and the E series had been out a few years.

My 3500 PST (USD) 100s are from 1998 So the switch was was probably between 1999 and 2003

Pete

 

[walesjoseywales]

SPECKS FROM TDI SHOWS NOT MUCH DIFFERENCE IN WIEGHT..PST E7-100 3442 PSI 100 7.25 Galv 24.12 33 -1 -8.5
PST 100 3500 102 7.25 Galv 23.94 34.1 -1.3 -8.8
SHOWS 1.1 POUND DIFFERENCE 33-34.1 WHEN EMPTY