Here is something I learned today about DIN plugs

[Umuntu]

They are not used to keep the threads "clean"
They are used to prevent damage to the valve during transit or lose of the gas.

They are used for what one chooses to use it for ... I choose to use mine to help keep my valves clean. I really don't mind losing a bit of gas.

Seriously you've had a DIN plug back out the 7 threads of a 200 bar valve and the oring is STILL sealing? Bull

I think there are only 5 threads in a 200 bar DIN valve ... 7 threads are in a 300 bar DIN valve.

 

[doctormike]

The non-vented SS ones are about 1/3rd the price. I still have about 15 of them from before vented ones were even created/made. They also don't get mud or crud stuck in the vent when your tanks gets dragged through cave by a bunch of not-so careful dry caver Sherpas. I use my non-vented ones, they are fine as long as I have a hefty wrench along. Even the vented ones sometimes need a wrench to remove as well - the oring gets wedged in there pretty tight when pressurized.

Delrin are useless

I guess you have more experience than me, so I'll defer to you. But I would think that for $20, it's not such a big expenditure in the context of technical diving. Also, if they really get caked with mud in that unusual situation (dragging them valve first through the dirt), then I guess you now have an unvented plug, which still works.

I have only had this happen once with a steel non-vented plug, and I almost stripped the threads and broke my wrist trying to get it open - it was incredibly tight.

 

[doctormike]

They are used for what one chooses to use it for ... I choose to use mine to help keep my valves clean. I really don't mind losing a bit of gas.

Yeah, sure, you can do what you want, no scuba police. But the whole point of this site is that we listen to each other and maybe change what we do. So maybe check out the Delrin plug entrance wound that was posted upthread - I have heard of that happening more than once.

 

[Scared Silly]

I have never tightened a din plug into a valve other than just snug. whet I have found is that depending on which tank valve is used. Only seen a couple like this. the 300 par valves i have seen have a vent built into the valve so as you loosen the plug and the seal is broken and it vents. the 200 bar valves ive seen do not have this vent in the valve. you unscrew it till you are out of thread and it becomes a rocket if the tank valve is leaking or not fully shut. You have to try to have it vent via the threads if you can.

I do the similar, only tighten mine finger tight. I know of the vent hole as when I first saw it on my 300 bar valves I wondered about it. I have not experienced what you have with 200 bar valves more like about half way out and it vents. But then again, the valve was opened but then shut so was not still "leaking"

 

[rjack321]

I guess you have more experience than me, so I'll defer to you. But I would think that for $20, it's not such a big expenditure in the context of technical diving. Also, if they really get caked with mud in that unusual situation (dragging them valve first through the dirt), then I guess you now have an unvented plug, which still works.

I have only had this happen once with a steel non-vented plug, and I almost stripped the threads and broke my wrist trying to get it open - it was incredibly tight.

I have a few vented ones but my non-vented ones I bought around 2005. I have about 20-22 total. Over $400 in DIN plugs in 2020 dollars. I doubt mud would hold back 3800psi but the buttons do get stiff with use and there's even more sealing orings in the button that your whole trip potentially ends up dependent on.

Mine vent in about 1.5 turns with a 12" adjustable wrench. The oring will be trashed. You still need to bring a wrench even with the vented ones, although the orings don't get ruined in one use. You won't strip DIN threads, although intentionally reefing on them every time probably isnt wise.

 

[АлександрД]

I`m using this type of DIN plugs:

It has not any holes in this Polypropylene plug. And I`m do not worry about any explosion. Reason is very simple - I use just DIN 300 valves (for 300 bar composite tanks, like above).
And it is original plugs, came with valve.

and this valve (as most DIN 300 valves) has a special safety hole under DIN connector - you can see it on the picture

I use this plugs to protect thread edges, and to cover DIN connector from any dust and particles.

BTW - is anybody know about topic here, dedicated to discussion about sweeping-out of DIN caps from regulators?