Problem with DIN valves and dust caps/plugs

[Sonic04GT]

Edit - Read the reviews on LP and I guess this is normal according to other divers. Nice that it keeps air from escaping but it sucks needing a wrench to get it off. Guess I'm adding a larger adjustable wrench to my kit haha

I have a pair of Worthington HP100s with the Thermo valve, purchased new a couple years ago.

I have been using the standard rubber/plastic valve caps that you commonly see on every tank until I was told by an experienced diver that I should get plugs that actually screw in, with an o-ring to keep contaminates out. So I went on LP and bought 2 of these....

XS Scuba, Stainless Steel DIN Plug

They screw in just fine, but stick out a little bit.
http://i295.photobucket.com/albums/mm142/thealmightyhubbard/IMG_1543.jpg

I put it finger tight, but when we got to our dive location today, I, for the the life of me, could not get it to unscrew. Of course the one day I really need my save-a-dive kit with a wrench, I leave it at home because it's under construction and was just a short shore dive. Fortunately a local snack bar had pliers for me to use.

Was a little difficult to unscrew but it eventually loosened and a tad bit of air purged.

So, obviously, when I was carrying the tank, I turned the valve a tiny bit, just enough to let air out and exert pressure against the plug since it's sealed by the o-ring. I didn't hear any air when I turned the knob of course because of the plug in place.

Happened again after the dive but was a little easy to get off, had to use pliers again though once I got home.

Is this normal? Is this harmful to the threads trying to unscrew it under pressure? Once that tiny bit of air escapes, it screws in and out with zero effort.

 

[Scared Silly]

The plug sticks out cause they are made to fit either 200 bar (5 thread) or 300 bar (7 thread) DIN valves. You have 200 bar valves so they stick out. The purpose of those plugs is 1) keep the valve from being damaged if hit and 2) keep you from losing your gas in case the valve gets turned. What you experienced in normal. The valve got turned and the plug pressurized. To loosen you need a 1" wrench like this one: Craftsman 6 in. Beak Jaw Adjustable Wrench Reviews - Craftsman Community which fits nicely in a save a dive kit.

 

[tbone1004]

we use those when we are travelling with trimix so we don't lose any gas if the valve gets turned. That can easily turn into a $300 woops. Won't hurt the valve or the plug since you're releasing pressure on the threads not increasing and the valve is designed to withstand that amount of pressure anyway since to the valve it's no different than having a first stage screwed on

 

[Tortuga68]

Edit - Read the reviews on LP and I guess this is normal according to other divers. Nice that it keeps air from escaping but it sucks needing a wrench to get it off

Yep. Some plugs have a hex screw in the head to relieve the pressure; best of both worlds

 

[rjack321]

Is this normal? Is this harmful to the threads trying to unscrew it under pressure? Once that tiny bit of air escapes, it screws in and out with zero effort.

In time they will tear up the threads since the valve is brass and the plug is stainless steel. The oring on the plug will also get chewed up fast and need to be replaced.

Basically try not to crack the valve every time you carry the tank. If you are just diving cheap air or nitrox I wouldn't bother with the plugs. Just blow out any junk or water in the valve before and after every dive.

 

[Sonic04GT]

I guess I'll just have to be more careful when carrying by the valve. Saxplayer, although this is true, it takes at least a couple turns before ANY pressure is released. When I unscrew my reg is already completely depressurized and requires zero effort.
Although only using nitrox and air, I already bought them so I might as well use them.

 

[Jim Lapenta]

I have both the stainless steel and the delrin ones. If just filled with air the delrin are fine. I only use the Stainless ones when there is mix in them. Unfortunately that is not happening lately. The dives I want to do that require mix are too far with gasoline prices at nearly 4 bucks a gallon now. Plus the boat ride. 1 dive could cost 250-300bucks.