ATX DS4 first stage blow out!

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partha

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Messages
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Location
asia
# of dives
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My DS4 first stage DIN regulator blew right off the cylinder after the air was turned on. The DIN connector piece was still attached to the cylinder while the first stage shot right off. Any idea what could cause this? Reg is less than a year old and after reading countless reviews about APEKS bullet proof regs I'm a little concerned.

atx_01.jpg
atx_02.jpg
 
Photo doesn’t look like threads are stripped.
Sounds like the connector was not torqued correctly and accidentally loosened when you turned the hand wheel. Has it been overhauled lately, or changed from yoke to DIN?
 
What @JackD342 said.
Since threads intact, that means the DIN fitting had to be quite loose when it was attached to the tank.
I hate to say it, but likely operator error.

The way to prevent is
1) make sure the DIN fitting is torqued properly to the reg body (by asking the shop if they connect "by feel" or with a torque wrench; and
2) make sure you don't twist the reg body once it's pressurized on the tank.

I suspect what happened was that a slightly under-torqued DIN bolt was loosened and unscrewed when the handscrew was tightened on the tank. If the handscrew wasn't free to turn, it would actually unscrew out of the reg body as it went into the tank valve.

Don't mean to criticize, but ask your shop to show you how best to connect to the tank, especially when there's corrosion.
 
Do closely check ALL the threads for damage, too. From your description I wouldn’t be surprised if it was held by just a couple of threads when you pressurized it, which could cause damage.
 
Remember not to turn the 1st stage when tightening or loosening din wheel. I think that is what loosens the inner thread
 
The o-ring and filter are missing in the pictures
upload_2020-3-3_11-9-56.png


It takes several turns until the o-ring seals both the housing and the connector. If the connector is loose, it will leak.
If the housing was blown off the connector, it must have turned loose nearly all the way. That would have been visible, since the black spacer doesn't line up anymore. So the problem occured during disassembly at the previous dive.

Tightening the connector with a torque of 20Nm is required to keep it in place.
 
I saved my wife from a similar issue a couple of weekends ago. Her Mares MR22 DIN regulator did not look correct screwed onto the valve, I took it off and found the DIN fitting had loosened over time. A quick fix with an allen key and the reg was good to go. It wasn't loosened enough to have blown off like yours but it was loose enough that it would have viciously leaked upon opening the valve. Glad you (or anyone else) didn't get hurt and your gear suffered no damage (from the looks of the picture).

The Mares MR22 does not have a plastic piece like your reg to shroud the threads. I think I was able to spot the issue on my wife's 1st stage because of that. I am wondering if that black plastic piece on your reg affected your ability to see that the DIN connector was loosening.

-Z
 
The Mares MR22 does not have a plastic piece like your reg to shroud the threads. I think I was able to spot the issue on my wife's 1st stage because of that. I am wondering if that black plastic piece on your reg affected your ability to see that the DIN connector was loosening.

-Z
I actually like the plastic part as it's easy to test if the thread is loose by poking the plastic if it moves around the thread is loose.
I do agree that it can be harder to visually check but should be easy enough to test by hand.

I've once had a bit loose thread after that i started to test this way from time to time.
 
We were told in service class to check every so often. Torque specs on my reg is 230 inch lbs.

Sucks about the filter and o ring, but it's way better than the threads being stripped and needing a new reg (or at least housing).

I think it's really surprising you didn't just have a large leak as the filter and o ring need to be up against the body to seal.
 
https://www.shearwater.com/products/swift/

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