How to remove OPD coupler from regulator?

[wittmania]

A buddy gave me a 100lb propane tank that I'd like to start using to fuel one of my two turkey fryers for brewing. I have an adapter that fits into the left-hand threaded valve on the tank that I should be able to thread into the regulator that came with the fryer. The only problem is that I can't remove the OPD hand-tightening coupler from the regulator. The space between the plastic housing and the regulator itself is pretty thin, and perfectly round, making it really tough to get any traction on it.

Has anyone had success removing the coupler from a regulator like this? If so, how the heck did you do it???

 

[Shockerengr]

easy, take a 18mm deep wall socket and put it on the brass part on the inside of the plastic threaded part, then turn it out.