does m25 x 2 and 3/4 NPSM have the same neck oring?

[allouttry]

hi im new here, i just got introduced to the diving industry a year ago and now im working in a dive equipment store.

like the title above, i've read up that 3/4 NPSM and m25 x 2 even if they fit eachother, they have a danger risk of the valve not withstanding the pressure when filling.

that i do understand, what im curious is, are the oring for the cylinder neck is the same? ive tried googling this but i cant find any.

pardon my bad english.

 

[BoltSnap]

i've read up that 3/4 NPSM and m25 x 2 even if they fit eachother, they have a danger risk of the valve not withstanding the pressure when filling.

The valve WILL fly out of the tank within the first 8 - 10th fill if you put the wrong valve on the wrong tank. This happened a couple of times I know of in our area when uneducated persons screwed the wrong valve on a different thread type valve. There was some resistance in the final 1/3 way when screwing the valve in the tank put with pressure, they managed to screw it in all the way. The valve was OK the first 8 fills only to fly out after the 8th fill when an AI was pulling the tank from the truck. The valve flew out the truck and went through the door of another car parked close to the truck. Luckily, the AI only suffered minor injuries but the truck and the car suffered more damage. Thank God that no other injuries to people in this incidence. There was another such incident that I know about but I don't have the full details. I am sure that there are other incidents but I haven't heard about them.

 

[claymore]

Working where there are 2 similar tank valve standards is an accident looking for a place to happen.

 

[allouttry]

yes i know perfectly well about the BIG NO NO for different valve thread and cylinders. i also have read about the incident in australia and some incident in south africa.

i just want to know if the neck ORINGS between M25x2 cylinder and 3/4 NPSM cylinder are the same or not

 

[Scared Silly]

hi im new here, i just got introduced to the diving industry a year ago and now im working in a dive equipment store.

like the title above, i've read up that 3/4 NPSM and m25 x 2 even if they fit eachother, they have a danger risk of the valve not withstanding the pressure when filling.

that i do understand, what im curious is, are the oring for the cylinder neck is the same? ive tried googling this but i cant find any.

pardon my bad english.

Welcome to the 'board.

Glad you understand the issue between 3/4 NPSM and m25 x 2 threads.

The o-ring for a 3/4 NPSM and m25 x 2 valves will be slightly different. However, o-rings are flexible and in many cases one can use an o-ring of a slightly different size. So they could be interchanged if necessary.

Do not worry about your english, even us native speakers have trouble speaking goodly some days.

 

[tursiops]

In answer to the question posed by the OP, No, the metric o-ring for the M25 valve is called a M25x3. It is a slightly smaller ID (25mm), and a slightly smaller cross-section (3mm) than the Imperial 214 in the US, which is 1 inch (25.4mm) ID and 1/8 inch (3.175mm) cross-section.

 

[Coelacanthic]

Here in South Africa, it is illegal to import a cylinder with the imperial specs. Unfortunately some do exist. Hopefully they get weeded out at hydros and visuals.