"Steve Lusardi" fired this volley in
:

I would like to use a
salt water cooled condensor on the high pressure side and a freon gas
that changes state around -40 C. Please advise. Do I need an
accumulator of some description on either side?

Yep, you need an accumulator (fairly large one) on the high-pressure
side, and that's a good place to put the head-pressure switch.

However, I'd recommend a refrigerant that changes state at about -40F.

LLoyd