There is a standard fire coupling thread and it doesn't match anything plumbing related.
Fire hose connections vary from town to town because so many systems were installed 100years ago before the standard was written in the 60's. Around here, fire departments carry couplers for their own town and several adapters in case they get called to assist somewhere else.
A local fire sprinkler service company will know the answer for your area.
Thanks for the quick response. Just talked to the guys in the field again and their hoses have universal couplings on them, not fire hose couplings like they told me this morning. I have hydrant adaptors but never had to try and attach a fire hose to a water meter. Now I don't have to
Thanks Jimbo. Just got back from Grainger and Ferguson to pick up the parts to adapt a 1" totalizer to, what turned out to be, 2" cam and groove couplings. Time to throw it all in a box and FedEx it to WV.
What did we do before camera phones? The first guy I talked to this morning said they were using fire hose couplings amd the second guy told me universal couplings. A quick pic with the camera phone saved a lot of grief.