Valve & Tank confusions

[GDHLEWIS]

So I was gifted a 15 liter steel tank, problem is it came with a leaking valve. I have worked out its markings note M25 3/4nps and its to EN144. I have tried several dive shops and non have this specific sized valve. Thread sizes math but its the neck that's a different size. Its 24mm diameter if that is of any help.
If any one is able to help I would be highly appreciated. The tank manufacturer is Roth so am waiting to hear back from them at the moment. Tanks hydrostatically tested 2 years ago and seems fine based on a recent visual inspection (which is how we found the leaking valve).

I'm not overly interested in a double, but happy to get one if its the only option.

Cheers in advance for any help any one can offer as I am stumped

 

[inka]

Roth tanks are made in France, so if your tank has M25 stamped on the neck, it means the valve has to be M25 x 200 since December 2000, NF EN144-1
Before 1985, tanks necks had 3/4 NPS threads, but you must not fit a 3/4 valve to a M25 tank !!

 

[inka]

read this;

 

[Gone for diving]

problem is it came with a leaking valve.

Why not rebuild the valves?
Its probably needs one or two orings changed inside...

 

[inka]

Why not rebuild the valves?
Its probably needs one or two orings changed inside...

"its markings note M25 3/4nps..." The problem is, you cannot have M25 and 3/4 at the same time on the tank and the valve. It is M25 o 3/4 but not both. Roth makes tanks with M25 o M18, not 3/4 , so if the tank is stamped M25, the valve must be M25 ( DIN 5/8)
M25 valve:

Robinet DIN mono 232 bar

<div class="tab-content"> <div class="rte"> <h4>Robinet DIN mono 232 bar</h4> <ul> <li>Sortie: DIN G5/8"</li> <li>Filetage coté bloc: M25 x 2</li> <li>Livré avec tube plongeur et joint de bloc viton</li> <li>Oxy Clean</li> </ul> </d

www.bubble-diving.com

3/4valve:

Robinet Droit DIN avec pas de vis US NPSM 3/4 sans bouchon 230 bars

Robinet DIN avec pas de vis US NPSM 3/4 sans bouchon 230 bars

www.bubble-diving.com

spare parts:

Accessoires - Robinets - Bouteilles & Robinets

Venez découvrir la boutique en ligne de Bubble Diving pour l’équipement et les matériels de plongée comme les combinaisons, les bouteilles, palmes…

www.bubble-diving.com

 

[Gone for diving]

"its markings note M25 3/4nps..." The problem is, you cannot have M25 and 3/4 at the same time on the tank and the valve. It is M25 o 3/4 but not both. Roth makes tanks with M25 o M18, not 3/4 , so if the tank is stamped M25, the valve must be M25 ( DIN 5/8)
M25 valve:

Robinet DIN mono 232 bar

<div class="tab-content"> <div class="rte"> <h4>Robinet DIN mono 232 bar</h4> <ul> <li>Sortie: DIN G5/8"</li> <li>Filetage coté bloc: M25 x 2</li> <li>Livré avec tube plongeur et joint de bloc viton</li> <li>Oxy Clean</li> </ul> </d

www.bubble-diving.com

3/4valve:

Robinet Droit DIN avec pas de vis US NPSM 3/4 sans bouchon 230 bars

Robinet DIN avec pas de vis US NPSM 3/4 sans bouchon 230 bars

www.bubble-diving.com

spare parts:

Accessoires - Robinets - Bouteilles & Robinets

Venez découvrir la boutique en ligne de Bubble Diving pour l’équipement et les matériels de plongée comme les combinaisons, les bouteilles, palmes…

www.bubble-diving.com

So what you are trying to say is someone threaded in a 3/4 SNPT thread into a metric thread.. ???? Haven't looked at a chart yet, but both threads should be similar sizes...
but yes this is very bad if the wrong valve thread is in the wrong tank thread..

Question for the OP, where was it leaking?
At the tank to valve connection?
When you thread in the valve a few turns is there up and down play? And side to side?
Maybe send a picture of the internal threads....


It is possible that the valve has the right thread...
But I would want to measure both halfs with a vernier caliper and a pitch gauge...

 

[inka]

So what you are trying to say is someone threaded in a 3/4 SNPT thread into a metric thread.. ???? Haven't looked at a chart yet, but both threads should be similar sizes...
but yes this is very bad if the wrong valve thread is in the wrong tank thread..

Yes, someone fix a 3/4 valve to an M25 tank, and it is not compatible, though you can screw it, but one day, will not hold the pressure and ....
During a visual inspection, you should check that the valve thread and the neckthread are ok with a GO/NOGO gauge.
In this case, buy a new valve M25.

 

[BoltSnap]

It can be filled 8 - 10 times and then a big "booom" with the valve flying out of the tank damaging anything that comes in its way. It happened a couple of times here where I live and dive. Somebody installed an 3/4 valve on a M25 tank didn't think much of it because they were able to screw it in the tank with some resistance but it eventually was screwed in all the way and made a seal. In one incident, the valve almost went a car's door to the inside. The car was parked several meters away from the tank that was laying inside a van. The other incident, a DM's hand was slightly hurt when the flying valve just barely touched his hand while flying across the parking lot. The key thing is that it will eventually seal even with some resistance at the beginning and will work for about 8 - 10 fills and then it goes boooom.

 

[runsongas]

that looks to be a metalsub v dual outlet valve pictured though, which i don't believe is offered in 3/4 NPSM

https://www.tradeinn.com/diveinn/en/metalsub-twin-valve-v-m25/136596315/

 

[inka]

that looks to be a metalsub v dual outlet valve pictured though, which i don't believe is offered in 3/4 NPSM

https://www.tradeinn.com/diveinn/en/metalsub-twin-valve-v-m25/136596315/

metalsub makes valves in M25 & 3/4 , but you are right, maybe not the one above, which seems to be an M25x2 according to what i can see in the picture .

Tanks and valves – Metalsub

Still don´t know why the markings are M25 and 3/4, which is not possible,