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Discussion of diving methods and equipment available prior to the development of BCDs beyond the horse collar. This forum is dedicated to the pre-1970 diving.
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ScubaLawyer
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Reducer bushing sourcing question

Mon Jul 15, 2019 8:43 pm

I know the subject has been discussed before on here but i can't find the discussion so I'm asking again.

I'm replacing the reducing bushings on my old USN 1800 psi 38's. I have a NOS 1/2" tapered manifold I'm going to install.

I know McMaster-Carr sells the 1 3/8" bushings (at least that is the socket size) but I can't seem to find the correct M-C catalog number to order them.

I recall someone on here supplied that catalog number a while back. Would you be so kind as to provide it again?

Thanks,

Mark
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

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captain
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Re: Reducer bushing sourcing question

Tue Jul 16, 2019 10:11 am

Captain

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ScubaLawyer
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Re: Reducer bushing sourcing question

Tue Jul 16, 2019 11:06 am

Thanks Capt. Tom!

Assuming my 1941 dated tanks pass hydro I'll be posting pics of my rebuild. Mark
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

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SurfLung
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Re: Reducer bushing sourcing question

Tue Jul 16, 2019 11:32 am

Another Choice...
- I didn't like the stainless bushing because it is just too long and sticks too far out from the end of the tank. McMaster has other versions. I found (in my emails) that I ordered a few different ones (some galvanized) and settled on a black steel "High Pressure Steel" fitting. I think this is as close to the original bushings in material and length. Its rated to 3000 psi... Which is the 5/3rds Hydro pressure I should never even come close to with my 1800 psi Twin 38s. So these are what I've put on the latest Twin 38 projects. Here's the link:

https://www.mcmaster.com/4513k348

Here's a photo with the Stainless Reducer I think is too long. Might not be the same as Captains link...
Image
- I am re-doing this tank after being convinced the wire wrap (USN ShatterProof) had to come off. Sure enough a little corrosion had started where the wrap was trapping moisture. I'll be using the black steel fitting instead of stainless and protecting the exterior with Galvalite paint.
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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ScubaLawyer
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Re: Reducer bushing sourcing question

Tue Jul 16, 2019 1:52 pm

Thanks Eben. I'll check those out too.

M
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

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ScubaLawyer
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Re: Reducer bushing sourcing question

Tue Jul 23, 2019 5:00 pm

Couldn't decide as between Captain and Eben's suggestions so I got both cause they're cheap. (The bushings. Not Captain or Eben :) )

Jumping the gun a tad as hydro is this week on the 38's. Fingers crossed!

M

Image
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

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ScubaLawyer
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Re: Reducer bushing sourcing question

Mon Aug 12, 2019 11:32 am

ScubaLawyer wrote:
Tue Jul 16, 2019 11:06 am
Thanks Capt. Tom!

Assuming my 1941 dated tanks pass hydro I'll be posting pics of my rebuild. Mark
UPDATE. One tank with an initial hydro date of 10/1941 passed hydro no problem. The other tank with an initial hydro date of 10/1942 failed hydro. The guy that does my hydros is very vintage savvy and he was really bummed it didn't pass. If it would be possible for it to pass he would have done so. Currently looking around for an equivalent round-bottom USN 1800 psi ALFCO tank. I have the NOS 1/2" npt tapered manifold, new reducer bushings, new burst discs and bands but just one lonely 38 cu ft tank. Hate to sink any more $ and time into this project but I'm a glutton for punishment. If anyone gets a line on a replacement tank kindly let me know. Haven't decided yet between going forward and just abandoning the project. Such is life. :) Thanks. Mark
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

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Re: Reducer bushing sourcing question

Tue Aug 13, 2019 10:45 am

Mark PM sent

technidiver2
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Re: Reducer bushing sourcing question

Wed Oct 23, 2019 9:07 am

Question regarding the tanks and reduced bushing:

Can you hydro the tanks WITH the bushing in the tank? Or does it have to be removed for hydro?

I know a local who hydros 1/2 NPT but I don’t know if they’re able to do 3/4 NPT, so if I need a tank hydroed I’d just leave the bushing in. Let me know if this is an issue. Would hate to get into trouble with the scuba police again :)

TD

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ScubaLawyer
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Re: Reducer bushing sourcing question

Wed Oct 23, 2019 10:45 am

technidiver2 wrote:
Wed Oct 23, 2019 9:07 am
Question regarding the tanks and reduced bushing:

Can you hydro the tanks WITH the bushing in the tank? Or does it have to be removed for hydro?

I know a local who hydros 1/2 NPT but I don’t know if they’re able to do 3/4 NPT, so if I need a tank hydroed I’d just leave the bushing in. Let me know if this is an issue. Would hate to get into trouble with the scuba police again :)

TD
My friend's dive shop does in-house hydros. As vintage friendly as they are, they won't hydro with bushings in place. May have to do with the bushing psi rating being less than or equal to 5/3 hydro test pressure of tank. Dunno. My 2psi.
"The diver who collects specimens of underwater life has fun and becomes a keen underwater observer. .. seek slow-moving or attached organisms such as corals, starfish, or shelled creatures." (Golden Guide to Scuba Diving, 1968) :D

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SurfLung
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Re: Reducer bushing sourcing question

Wed Oct 23, 2019 4:55 pm

Maybe...
- We posted elsewhere about a Jack the Frogman tank with a strange bushing that is straight threads and O-ring... Converts a 1/2" NPT valve to screw on and off as easily as modern 3/4" Straight Thread valves. We hunted around unsuccessfully for a hydro tester who might have an adaptor to fit this tank. On a whim, we asked our latest favorite tester if he would try it with his 1/2" NPT connector and just use our oddball bushing/adaptor to connect. He said, "I can try". And so, all of a sudden our tank got a fresh hydro test and passed just fine... Using the bushing/adaptor to do the test.
- So, to answer your question... Maybe some hydrotesters might be fine with it.

viewtopic.php?f=41&t=9381
SurfLung
The Freedom and Simplicity of Vintage Equipment and
Vintage Diving Technique are Why I Got Back Into Diving.

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captain
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Re: Reducer bushing sourcing question

Thu Oct 24, 2019 10:52 am

If I recall correctly the CFR requires bushing to be removed so the tank threads can be inspected.
Captain

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luis
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Re: Reducer bushing sourcing question

Thu Oct 24, 2019 7:24 pm

captain wrote:
Thu Oct 24, 2019 10:52 am
If I recall correctly the CFR requires bushing to be removed so the tank threads can be inspected.
You are absolutely correct. For the required visual inspection, it is required to inspect the threads and therefore any adapter bushing has to be removed, during the visual inspection.

But to actually perform the hydro portion of the test you are using the needed fitting or adapter to create a reliable seal with the cylinder. There is no restriction on the type of fitting or adapter.

I actually had a custom adapter machine out of steel to test my European (Poseidon and Drager) metric tapered thread cylinders.

During the hydro test it doesn't matter if there is a bushing or any type of adapter as long as it seals, it can take the pressure, and it doesn't trap any air when the cylinder is being filled with water.

I have work in or with several hydro facilities and the connection fitting from the submerged jacket lid to the cylinder was not always the same, but they all had means to use different adapters with all the required thread connections for different cylinders.
Luis

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