Older cylinder

[Gerard Doherty]

I bought 2 old cylinders of a guy, more to help him get rid of them than anything. Says he hadn't used them in the last 10 years.

I am trying to decipher the markings on them to establish if newer modern pillar valves would fit. But I am struggling with the markings. Any ideas?

 

[tmassey]

I am far from an expert, but I’m pretty sure those are not SCUBA tanks. I can be fairly confident in saying those are not DOT 3AA tanks, nor are they DOT 3AL tanks (or any of the modern special permit tanks). Which means for all practical purposes in modern usage, those are not SCUBA tanks.

I can’t tell what the tanks are, so I can’t say if you’re going to be able to put a 3/4” NPS SCUBA yoke or DIN valve on those. However, I would find it extremely unlikely. And if they are anything other than 3/4” NPS, don’t bother: it’s hard enough dealing with tanks designed to be scuba tanks that don’t use 3/4” NPS, let alone something repurposed. So unless they actually have a 3/4” NPS thread, it’s going to be at best impractical to use them as scuba tanks, and most likely impossible.

it’s very hard to tell what those tanks are just from that bit of lettering. If those tanks are any kind of real metal, I would expect stampings into the tank. Seeing as they’re stamped into the collar, I wonder if those are composite tanks of some sort? Or some other balloon-lined lightweight tank? Which leads me to believe that they might be expired SCBA bottles? But honestly, all of that is just speculation.

I’m hoping that some wise ScubaBoard sage will be able to give us actual wisdom: I too am now very interested to find out what these are.

 

[Waterwulf]

Most likely SCBA tanks and possibly synthetic, not metal.

 

[MarkA]

What country? UK?
You can make out some markings. IWKA is a manufacturer. WC is water capacity (the volume). TP is test pressure. Is the date 2.75?

The ones I have seen with this type of pillar valve were tapered threads so unlikely to be M25.

 

[iain/hsm]

I bought 2 old cylinders of a guy, more to help him get rid of them than anything. Says he hadn't used them in the last 10 years.

I am trying to decipher the markings on them to establish if newer modern pillar valves would fit. But I am struggling with the markings. Any ideas?

The cylinder is IWKA Germany The pillar valve MDE Leicester and the cylinder was to a British HOT standard better known as Home Office Specification T. The thread once you remove it if you can will more than likely be 3/4BSPP and if you cant remove it you need to empty the cylinder first before trying.
And if its taper then try 1 inch Briggs thread or 3/4"taper to BSPT and if smaller try .715 taper as a 1 in 8 taper and 14TPI

By now I guess your in denial about being the proud owner of scrap.

Britain adopted the metric system in 1965. We are now in 2025, 99% of us don't know our weight in Lbs and ounces unless you are a mother with a new born baby. I cant give explanation for this.

94% of us don't know our height in feet and inches apart from one member of our anatomy.
And for reasons I won’t pretend to understand, the slightly older scuba diving demographic in Britain know more about navigation in the English channel in small rubber boats than old scrap cylinders.

After this, it goes downhill.

 

[MarkA]

The cylinder is IWKA Germany The pillar valve MDE Leicester and the cylinder was to a British HOT standard better known as Home Office Specification T. The thread once you remove it if you can will more than likely be 3/4BSPP and if you cant remove it you need to empty the cylinder first before trying.
And if its taper then try 1 inch Briggs thread or 3/4"taper to BSPT and if smaller try .715 taper as a 1 in 8 taper and 14TPI

By now I guess your in denial about being the proud owner of scrap.

Britain adopted the metric system in 1965. We are now in 2025, 99% of us don't know our weight in Lbs and ounces unless you are a mother with a new born baby. I cant give explanation for this.

94% of us don't know our height in feet and inches apart from one member of our anatomy.
And for reasons I won’t pretend to understand, the slightly older scuba diving demographic in Britain know more about navigation in the English channel in small rubber boats than old scrap cylinders.

After this, it goes downhill.

Thank you for the compliment "slightly older". And you are right as I probably know more about navigation in small rubber boats than old cylinders.

Find it interesting that the United Kingdom signed up for the metre convention in 1884 6 years after the USA. In the 6% that knows my height in feet and inches as it hasn't changed for a long time (also know it in metres). In the 99% though that only knows my weight in Kgs.

Learnt something about that pillar valve. Made by MDE and likely to be 3/4BSPP. Know that that valve hurts the back of your head more than a modern one.

 

[tursiops]

I bought 2 old cylinders of a guy, more to help him get rid of them than anything. Says he hadn't used them in the last 10 years.

I am trying to decipher the markings on them to establish if newer modern pillar valves would fit. But I am struggling with the markings. Any ideas?

One of the pix shows some stamped markings on the sidewall of the tank. Can you provide pictures of those markings?

 

[iain/hsm]

Thank you for the compliment "slightly older". And you are right as I probably know more about navigation in small rubber boats than old cylinders.

I did think to write senile old duffers with beards and sandals but thought better of it as the present demographic may think I was making reference to our current islamic visitors arriving in small rubber boats from France known as undocumented migration. While the BSAC need to take reference. (British `Sub Aqua Club) as they too are well known for beards and sandles while the women within the BS-AC wore beards and candles The BSAC were a bit like PADI only with cheaper subscription rates for the UK working classes.

Learnt something about that pillar valve. Made by MDE and likely to be 3/4BSPP. Know that that valve hurts the back of your head more than a modern one.

MDE or Midland Diving Equipment have made pillar valves since the very beginning interestingly the one in the photo made from brass and (if) its indeed a 3/4 BSPP would fit both versions of the 3/4 BSPP cylinder thread A thin cross section 0-ring for cylinders that were threaded with a counterbore (stepped) or groove and a sightly larger (fatter) 0-ring with a larger cross section for cylinders cut with countersunk
as per the European cylinders.
MDE also were the first company to market Aluminium diving cylinders manufactured by Luxfer Cowlick Nottingham under another home office standard HOAL 1 that then became HOAL 4 Then HOAL 2 then HOAL 3 before British standards came out and the Home office standards were superseded.

Steel cylinders back then in the UK were also under Home Office standards like the OP's cylinder
HOT the T stands for high tensile thin wall T light weight cylinders for the likes of firemen and the another standard was HOS the S was for as heavy as heck.

MDE were also the UK and Europe distributor for US Divers sports diving equipment and the KMB-10 Commercial Divers Band Mask. In addition to packaging Bristol Pneumatic compressor blocks known as the MDE Whirlwind range and supplied and maintained the US Divers Conshelf XIV Supreme regulator for the Royal Navy.

 

[iain/hsm]

One of the pix shows some stamped markings on the sidewall of the tank. Can you provide pictures of those markings?

You sure it's not just bird poop or a camera flare. As stamping the side wall of a HOT spec thin wall cylinder would result in an instant fail. The brass collar was the only area allowed for stamping they were replaceable if you knew what you were doing. Although at the time as now few scuba shop hydro folk knew how.

 

[tursiops]

You sure it's not just bird poop or a camera flare. As stamping the side wall of a HOT spec thin wall cylinder would result in an instant fail. The brass collar was the only area allowed for stamping they were replaceable if you knew what you were doing. Although at the time as now few scuba shop hydro folk knew how.

You seem to know a lot about bird poop. You decide.