Thermo Valve copper crush ring

[tmassey]

I understand that the copper crush rings in Thermo valves are single-use. Does anyone have a generic/bulk source of these, or alternatively, the dimensions? I'm hoping that I can find a bulk source for these rather than paying scuba prices each time I might need to clean and lubricate a valve!

I've found SCUBA sources for these, but at $1.20 each (plus 4 x the price for shipping!), that's pricey. It's like buying individual o-rings from a SCUBA shop -- I don't do it! I know that it can be possible to re-anneal the rings, but in this case, the savings is not big enough to bother, and even moreso if I can find the generic equivalent.

Thank you for your help!

 

[tmassey]

OK, so I thought I would see what I could do to further this. I bought 3 x copper crush gaskets from Northeast Scuba Supply. It says that they fit Sherwood, Thermo and others. So, I figured I would measure one before I put it on.

When I got them and compared to the one I pulled off the valve, they are noticeably different.

WARNING: I am not a QC engineer. My calipers are very low-end and I'm not skilled in their use. Please do not stake your life on my measurements! (But the difference in ID is not a mistake: they're quite clearly different.) Also, all of these are measurements: none are mathematical conversions. The metric measurements are probably the most accurate (finer gradations on that); the standard measurements are accurate to well less than a 64th, but just don't offer the same precision as the metric. And the thinner ring was hard because it's not even round, so the fact that it varies by 0.3mm doesn't surprise me: I can make it vary by simply measuring different diameters of the "circle" (oval, really).

The dimensions I measured for the new ones I received: 5/8" OD | 17/32" ID | 1/32" Thickness or 15.3mm OD | 13.2mm ID | 0.8mm Thickness.

However the old, used one that I took off the valve had a quite different ID: 5/8" OD | 7/16" ID | 1/32" Thickness or 15.6mm OD | 11.0mm ID | 0.8mm Thickness.

So, which one is right? Does anyone have a Thermo rebuild kit where they could measure the dimensions? I'd love to know what other people have in their possession...


So I went ahead and put together the valve with the parts that I have: a new stem, a new teflon packing, a new o-ring (both of these from a valve rebuild kit), and a new copper gasket (which I got from Northeast Scuba Supply). Everything fit back together. The new teflon packing was *much* tighter in the bonnet than the old one: I have a feeling that this may contribute more to being leak-free than the new copper gasket...

In any case, I put a tank checker on the valve, opened the valve, closed it and left the valve pressurized for an hour. Dead-on where I left it. So that valve is solved...

But I'd love any feedback you might be able to give me regarding your copper crush gaskets!

 

[Pao]

It is a "crush" washer. Perhaps it expands/gets flattened during assembly? But that 2.2 mm difference in ID seems a bit too much to be explained by expansion. Maybe you can re-measure it come service time?

 

[tmassey]

I'm sure it does get flattened. Relatively--it's not toothpaste. And physics says that unless the thing started twice as thick as it ended, it wasn't the crushing that widened it... You can see/feel an indentation in the copper, but it's not overly changing the dimensions...

 

[tmassey]

I've found some more information about crush washers and dimensions! eBay to the rescue.

eBay seller maxdive2007 has both types of crush washers. His items have actual dimensions and even describe why there are two different sizes:

Thinner/Narrower: OD: 16mm | ID: 13.2mm | Thickness: 0.6mm BG06-2C

Thicker/Wider: OD: 16mm | ID: 11.2mm | Thickness: 0.8mm BG06-1C

The item descriptions also mentions why there are two sizes. The thicker one will not allow the valve seat to be removed without removing the copper gasket. The thinner one allows the seat to be removed without removing the gasket. (Of course, seeing as they're not supposed to be reused, who cares if you have to remove it!)

It sounds like as long as the thing is no bigger than 16mm OD and an ID between 11 and 13mm or so, it'll probably work. I'm pretty impressed with how close this corresponds to my actual measurements -- particularly if that OD is nominal, which it is very likely to be.

They're even somewhat reasonably priced: $7 for 10 shipped (but slow boat from China -- plan ahead).

But if you're willing to go a little off-book, you can get something like this:

https://www.amazon.com/uxcell-11mmx16mmx1mm-Copper-Washer-Gasket/dp/B00WW79DUM/

That's $4.46 for 20. Or you can pay $7.23 for 50. That's less than 1/10 the cost of buying them individually at a dive shop.


I'm guessing from the near total lack of response to this thread that the rest of you simply re-use the crush washer? (I know that there aren't too many of you gladly spending $2 every time you take apart a valve.) Honestly, that's what I've done in the past without issue, but I've only taken apart a valve once or twice--I didn't even know that it had to be replaced each time.

In this case, I had a bent stem, and my valve leaked even after I had replaced it and the o-ring. In the end, I replaced the copper gasket and the teflon packing at the same time and it fixed it. Comparing the old packing to the new, I think it was the packing that fixed it.

But at 15 cents each, I can treat them like o-rings and replace them any time I open the thing up. Maybe now you can too!

But if any of you have any experience or knowledge in this area, please share what you know!

 

[grf88]

The advantage of the larger washers is that screwing out the seat pulls out the washer. You don't have to fish it out with a pick that can sometimes be an issue.

 

[a878bob]

Thanks for doing the research, I know some who do reuse the copper washer, but I personally don’t. I’ll look into your sources. It would be nice to have a list of resources for the Teflon packing and the seat as well, orings are easy enough to get in bulk.

 

[tbone1004]

Thanks for doing the research, I know some who do reuse the copper washer, but I personally don’t. I’ll look into your sources. It would be nice to have a list of resources for the Teflon packing and the seat as well, orings are easy enough to get in bulk.

I need the teflon sizes as well, just haven't gotten around to measuring them yet... Unfortunately I think the seats are going to be hard to find independently

 

[grf88]

I need the teflon sizes as well, just haven't gotten around to measuring them yet... Unfortunately I think the seats are going to be hard to find independently

Not that hard:
maxdive2007 | eBay Stores

 

[tmassey]

I just spent several hours on the PTFE (Teflon) flat washer situation...

tl;dr: maxdive2007 seems to be competitive on these.

I found that in low quantities the PTFE flat washers are pretty expensive compared to o-rings or even the copper gaskets: roughly $1 each (or more) in quantities of less than 100. In that case, at $7 including shipping, maxdive2007's price for PTFE flat washers seems very reasonable. The only downside is the usually 30 days it will take to get them: plan ahead.

You wanted dimensions: maxdive2007 has them, and I've included them below. As you no doubt know, there are three sizes. One is for stems that have an o-ring. The other is a pair of parts that are used with stems designed to not use an o-ring.

For both, the ID and OD are the same. It is listed as OD: 11.2mm | ID: 6.3mm. Given that all of the other Thermo dimensions for all the other parts are Standard, and after all of the practice I got with copper gaskets described above, I am pretty confident that this translates to OD: 7/16" | ID: 1/4".

There are three thicknesses. The pair used without an o-ring are the "thick" and "thin" washers. They are listed as 0.8mm and 2.7mm, but again I'm pretty sure that this should actually be 1/32" and 0.10". The single washer used with an o-ring is the "medium" washer. It's listed as 1.7mm, which is probably supposed to be 1/16".

It turns out that 1/32" and 1/16" are standard thicknesses, and 1/4" ID (0.253" for clearance) is standard, too. What is *NOT* standard is 7/16" OD. The standard for 1/4" ID is 1/2" OD, so it won't fit. In addition, it seems that the 0.10" thickness is also harder to get.

Here is a source that can provide every size you can imagine. They even have the "thin" and "medium" washers in stock (but not the "thick"). The pricing is not outstanding: Under qty 300 and it's anywhere from $0.80 - $1.30 each.

Thin: Seastrom
Medium: Seastrom

(Above qty 300 pricing drops in half, but I'd rather pay $0.70 each qty 10 from maxdive2007...)

So, it seems that just getting qty 10 is probably the best way to go. For me, this is fine: unlike the copper gasket these are able to be examined and re-used, so I won't use nearly as many of these as the copper gaskets.