Hydro testing dive cylinders - Taper thread HOT type (Non IDEST)

Tackle Sack

New member
Hi All,

I posted a thread on FB about this and thought it would benefit some folk that might not have access to the CDG group on FB.

I have some old taper thread IWKA HOT cylinders, 21 cubic ft and 30 cubic ft. 2840 psi working pressure.  Sorry I?m too old to tell you the metric capacity 😁.  I bought them in the early 1990?s and, then, everyone quoted cylinder capacities in cu ft. 

They are nice and light and great for longish transits to short sumps, or for a back up stage tanks.  But it seems that the current Dive Shop cylinder testing regime; IDEST, will not touch them. 

It was suggested I approach a tester of industrial cylinders, specifically a well respected company, CTS, who are based in Liverpool.  http://www.ctsukltd.com.  Thanks for the tip Chris J.

I contacted CTS who confirmed they can test HOT IWKA taper thread cylinders 👍

I dropped them off today and the costs are as follows

Taper thread Hydro test = ?15
Parallel thread test = ?16 (?1 for the new ?O? ring!)
Zinc & paint ?18

There is a 2 week lead time.

My cylinders were a bit battered so needed Zinc and pant.

The testing CTS carry out conforms to UKAS and Arrowhead standards.  They were quick to mention that these testing standards exceed the IDEST requirements 😮.

See weblinks I found

https://www.gov.uk/government/news/ukas-accredited-cylinder-inspection-and-test

https://arrowheadindustrial.com/

They might pass, might fail, but at least they will test them. 

GW
 

PeteHall

Moderator
That's half the price of an IDEST test!

While this will obviously give you peace of mind (assuming they pass), will a dive shop be happy to fill them?
 

Tackle Sack

New member
Hi Pete,

I did pose this question to the guys at CTS, and they said that some shops might not like it.  But they do a lot on dive cylinder testing and they were flat out testing divers bottles post lock-down.  So compressor shops must accept them.

Anyway, the times I have purchased a ?fill? at dive shops they charge it quick and hot leaving me with, at best, 210b of a 232 cyl.  Or worse, forget to fill it and still charge me!  Yes this has happened.

G

 

PeteHall

Moderator
I've been getting fills at the South West Maritime Academy at Cromhall Quarry recently. The fills are usually quite generous and not too expensive. The last 300bar fill I had was still a solid 300 when I got in the water.  :)

It also helps that they less than a mile away from home.

I'll ask them what they think of industrial testing next time I'm up.
 

mrodoc

Well-known member
Make sure the taps have been threaded appropriately if removed for testing. The late Phil Luxford in Cornwall describes cylinders, recently tested, being given to him that blew their taps off shortly after filling. The taps had been replaced and were wrongly threaded. One tank circled the compressor room before launching through the roof and landing on a car door in his camp site next door. He survived unscathed.
 

Tackle Sack

New member
Yup.  Nothing worse than having to pass some perfectly serviceable tools or equipment for calibration, or testing, only for the human error factor to mess it up!
 

PeteHall

Moderator
By way of update, I was at SWMA (Cromhall) this morning for a few fills and asked the question about industrially tested cylinders.

The response was that legally, a cylinder must be tested, but the law says nothing about idest, so a dive centre should fill a non-idest tested cylinder. Some places apparently can get a bit funny about it though.

Interestingly, he also recommended CTS as the cheapest place to get a test done (and he's an idest tester).
 

mrodoc

Well-known member
Takes me back to the 70's when my father and I took some tads in to be filled at Kingsbridge Water Sports. They were really funny about filling despite being in test, on the grounds that they were very old (ex 2nd world war). Admittedly they had had some dodgy tanks left including one that had had a patch welded on it!!  Move forward to now and I am still getting a cylinder filled that I bought new in 1990 and it passes its test regularly.
 

Pitlamp

Well-known member
PeteHall said:
By way of update, I was at SWMA (Cromhall) this morning for a few fills and asked the question about industrially tested cylinders.

The response was that legally, a cylinder must be tested, but the law says nothing about idest, so a dive centre should fill a non-idest tested cylinder. Some places apparently can get a bit funny about it though.

Interestingly, he also recommended CTS as the cheapest place to get a test done (and he's an idest tester).

I think the problem may be that a quite different area of legislation gives traders the right to refuse to sell something if they so wish. The IDEST regime (or, as some say, "cartel") would argue their stance is based on the health & safety of the employees who have to fill cylinders. I'm not totally convinced though, provided cylinders are in test to our national specifications. It has been argued that it's great for sales of new cylinders.
 

Pitlamp

Well-known member
Incidentally I have complete faith in my local test house (which is IDEST). The bloke running the show is good and he's looked after CDG members for a long time. On the rare occasions when he's failed a cylinder of mine (bearing in mind I get several tested each year) I'm happy to accept his judgement. After all, none of us would want to be next to (or strapped to) a cylinder which fails in use.
 
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