Sprinkler Valve Hook-Up

[ABLE1 <somewhere@xxxxxxxxxxx>]

Hey you's guys,

I am connecting a Fire Alarm system to a new sprinkler system.
The valves installed are a bit different in that the connection
where the wire leads exit the valve body has a unknown
female thread.

http://www.aleumusa.com/products/but...e-grooved-300/

It is smaller than a 1/2" NPT so I can't use a Chase Nipple into a
box for the wire splice. There was a rubber threaded hex nut
already installed but I don't think it will hold up as a metal
Chase Nipple.

This rubber plug appears to have a straight thread not a tapered
which is also odd. The outside diameter of the threads is .790".

Does anyone know what kind of thread this might be and/or
what can be used to adapt to it in order to make a secure
connection of a junction box??

Sadly the instructions are skimpy on the details.

Thanks for any assist,

Les