Info Scuba Cylinder Valve Installation

[Akimbo]

There's nothing very tricky involved but the ratchet strap on the fence post tip is really going to make my life simple.

You may not even have to resort to that. You might try holding the cylinder with your legs first. It works somewhere between sometimes and usually. It can be awkward for some people so enlisting a second pair of hands improves your odds. Glad it helped. Let us know how it worked and if you come up with any tips that I missed.

 

[cool_hardware52]

Ratchet Straps and utility poles can be effective, but as an alternative place the cylinder against a curb pin it in place with an auto tire. If you pick the right spot in the street, i.e. next to a curb cut for a driveway wrench access is OK, not great but OK. You may have to re-position the cylinder a couple times. This can generate a *lot* of clamping force when there is no telephone pole handy. I have an old leather welding apron I use to wrap the tanks.

Tobin

 

[Sam Miller III]

Ratchet Straps and utility poles can be effective, but as an alternative place the cylinder against a curb pin it in place with an auto tire. If you pick the right spot in the street, i.e. next to a curb cut for a driveway wrench access is OK, not great but OK. You may have to re-position the cylinder a couple times. This can generate a *lot* of clamping force when there is no telephone pole handy. I have an old leather welding apron I use to wrap the tanks.

Tobin
~~~~~~~~~~~~~~~~~~~~~~~~
Ya beat me to it !

That was the preferred method of valve removal by individuals and SoCal dive shops

Went along with the "Hawaiian Hydro's" of the same era

SDM

 

[bergersau]

You may not even have to resort to that. You might try holding the cylinder with your legs first. It works somewhere between sometimes and usually. It can be awkward for some people so enlisting a second pair of hands improves your odds. Glad it helped. Let us know how it worked and if you come up with any tips that I missed.

The post and ratchet strap worked very well, thanks.

The valve was too tight for the leg grip trick to work. It was only a little Catalina S19 that I use as my pony. The cylinder diameter is to small to grip without a secure way to clamp it in place.

 

[Akimbo]

Can anyone fill us on the history behind the Sherwood 7/8" valves? Does anyone make new cylinders for them? Is the XS Scuba 7/8-14 UNF DIN Valve the only replacement valve on the market?

 

[Hickdive]

The only thing I would add is to be beware of different neck threads.

In Europe and many parts of the world cylinder neck threads are 25mm. A 25mm thread valve will not screw into a 3/4" neck thread cylinder. However a 3/4" valve will appear to fit a 25mm cylinder. It will screw in quite loose and then tighten on the last few turns. It is then only those last couple of turns that are actually holding the valve in the cylinder and eventually they WILL fail with disastrous consequences.

In addition there are older cylinders, particularly from the UK that have 3/4" neck threads. However these are 3/4" BSP and not 3/4" NPT as used in the USA. The thread pitch is different and therefore 3/4" NPT valves cannot be used in 3/4" BSP (aka G3/4) cylinders. Cylinder fillers should be suspicious if they see new-looking valves with burst discs installed on older UK cylinders.

In short, be aware of neck thread size on both cylinder and valve and be absolutely certain they match. If in doubt get a set of ring and plug go/no-go thread gauges to double check. Bare in mind that is unlikely a valve manufactured in North America will have the correct thread for a European cylinder and vice versa.

 

[Akimbo]

The only thing I would add is to be beware of different neck threads.

Thanks for the heads-up. I understand the European Scuba cylinder valves do not have blow out plugs like those in the US. Is that correct? If true, would that be a reliable indicator of thread incompatibility?

 

[guruboy]

Can anyone fill us on the history behind the Sherwood 7/8" valves? Does anyone make new cylinders for them? Is the XS Scuba 7/8-14 UNF DIN Valve the only replacement valve on the market?

No one makes 7/8 tanks anymore.

That is probably the only source for a new valve / manifold.

 

[Couv]

I would love to see the first couple of post by Akimbo + the post by Captain + the warning by Hickdive made into a Sticky.

 

[Kovach]

First of all - Akimbo - thanks for this!
This is a very useful info, especially having in mind how many questionable theories is out there.
For me - timing couldn't be better as well, since I need to put my doubles together, probably tomorrow.
In other words - this is my first post here.

I have only one question regarding this part:

For Air Service Only:
Dow Corning Molykote 111 (previously Dow Corning Silicone 111)

For Nitrox and Oxygen Service:
Engineered Custom Lubricants: ChristoLube MCG 111 and ChristoLube MCG 129
Aerospace Lubricants: Tribolube 71

I currently have ChristoLube MCG 111-5g - but these doubles are gonna be mostly for air service. Maybe Nitrox (<40%) - but probably 95% of the fillings are gonna be air.
Is it okay for me to use this lube for air service tanks?

I've read whatever I could find on this, but I wasn't able to find this distinction.

Thanks in advance!

Regards.