3/4" vs. M25 (metric) thread - what's the difference?

[Vie]

First, please let me apologise for my ignorance...

I am looking to buy a 300 BAR isolator manifold and have come across two types: 3/4" and M25 (metric) thread. What are these numbers referring to?

Are the thread numbers in reference to the DIN connections or to the connections between the neck of the tank and the manifold?

If someone could answer my questions or point me to an old thread(s) I would be extremely grateful. Thank you!

 

[padiscubapro]

First, please let me apologise for my ignorance...

I am looking to buy a 300 BAR isolator manifold and have come across two types: 3/4" and M25 (metric) thread. What are these numbers referring to?

Are the thread numbers in reference to the DIN connections or to the connections between the neck of the tank and the manifold?

If someone could answer my questions or point me to an old thread(s) I would be extremely grateful. Thank you!

Thats the valve opening that it fits..

european tanks use m25 (actually a few others are comming in), the US and Australia use 3/4

Everywhere else you have to find out what the local tanks in use are..

 

[Vie]

Ah, I see. Thank you very much.

 

[oxyhacker]

It's an unfortunate coincidence, that the two sizes are so similar in size and thread count, because it means they can be switched around accidently (the M25 valve in a 3/4" NPTS tank in particular), with potentially lethal results. So if you are in an area where both tanks are in use, extra care is necessary.