HPA tank threads?

[tolley]

Is there a standard for the the thread size used on High Pressure air tanks? I am asking because I need to replace the regulator on my ACI Bulldog II. I purchased one used online from an ACI Bulldog I. I made the mistake of thinking that since they were the same brand it would fit. Turns out that the Bulldog I is 5/8" flare(I think), and the Bulldog II is 1/2" NPT.

Anybody know if there is a standard? I don't want to make the same mistake again.

PS: Since the two sizes are so close an adapter won't work.

[xen_100]

the only two sizes I am aware of for tank threads are 5/8 - 16 and 3/4 - 18.

no, there is no adapter, that would not be safe. you need to simply order the correct size tank for the threads of the reg you have ( or order a reg for the size tank threads you have)