Here is something I learned today about DIN plugs

[Storker]

Why not dive it with the new info? No prejudice in the question. Just curious about your experiences.

Because if both analyzers are right, they should agree within experimental error. If they don't agree, one of them is off and I don't know if it's the fill station analyzer that's off, or if it's my personal analyzer that's off. Until I know which analyzer is sensible, I can't trust either result.

Yes, I know. Within rec limits, it probably - usually - doesn't matter very much. I still prefer to know fairly certainly which mix I'm diving. If I can't trust my analysis, the ocean will still be there another day. Calling a dive sucks, getting in trouble because you didn't call the dive sucks more.

 

[txgoose]

Because if both analyzers are right, they should agree within experimental error. If they don't agree, one of them is off and I don't know if it's the fill station analyzer that's off, or if it's my personal analyzer that's off. Until I know which analyzer is sensible, I can't trust either result.

My limit might be a bit wider than yours, but I definitely get this logic. There may also be some room for two analyzers to be consistently calibrated a bit off or each other. But to your point, I'd want to have established that track record well before blindly trusting it.

Edit, not calibrated off. they should both be calibrated against air. I meant that two analyzers could consistently read a bit off from each other.

 

[Storker]

they should both be calibrated against air.

Well, there's your problem right there. It's perfectly possible for a cell to calibrate well against 21%, but have linearity issues when measuring higher percentages.

Proper calibration requires calibration against both higher and lower percentages than your measured value. Problem is, we rec divers usually don't have access to higher percentages than our breathing mix. I get around that problem by requiring two different analyzers to agree. The risk of two cells failing in the same way is acceptable to me.

 

[rjack321]

1) Preventing gas loss - use a steel plug with a relief valve

I can't think of any scenario where a Delrin plug or a steel plug with no valve would be an optimal solution.

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

 

[NAM001]

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.

 

[pauldw]

I have found a new calling in life: creating a specialty course, to be called DIN Plug Diver. It'll probably be like Nitrox; no actual dive required. Just an damage waiver.

 

[Umuntu]

Delrin are useless

I prefer and only use Delrin. I stopped using metal DIN plugs and metal DIN reg dust covers because of galvanic corrosion issues. There would be a white powder left on the threads.

 

[rjack321]

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.

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

 

[rjack321]

I prefer and only use Delrin. I stopped using metal DIN plugs and metal DIN reg dust covers because of galvanic corrosion issues. There would be a white powder left on the threads.

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.

 

[NAM001]

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

no that is not what I said I said a 300 bar valve will vent when the o ring unseats where I have never seen a 200 bar valve do that. If I use a wrench on a 200 bar plug under pressure it will launch when I unscrew it at the point of the clearing the last thread depending on the PSI on it. I have had a gage under pressure but not tight tried to spin out of the pipe fitting last week.