After receiving most of the filters and fittings, I connected everything of what was available to test for air leaks and filtering capability. At this time the only things not tested were the separation membrane and the molecular sieve dryers, both of which were not tested because I did have them yet. All the fittings and connectors are 1/4 inch NPT to keep things simple. Make sure to use thread tape or some sort of thread sealing compound. NPT was designed as an interference fit and it was designed to work only with pipe sealant. I used thread tape with about 3-4 wraps. The connections between the parts that are further away are done with 37 degree flared fittings for stainless steel tubing. I chose to use stainless steel because it has a better tolerance for lower temperatures and because it was cheaper then copper tubing.
When I was done connecting up all the parts, I filled the system with air to approximately 40 PSI to test for leaks. I plan on leaving the system pressurized overnight and checking to see if the internal pressure has dropped at all.
Possibly the hardest component to procure in this project is going to be the nitrogen separation membrane. I'm hoping to get lucky and find one cheap on eBay, but otherwise I've been scouring the web for any supply of the membrane.
The next step is to glue up the PVC chambers for the molecular sieve dryers and thread the flared fittings onto the end of the pipes. Hopefully the stainless steel tubing should be here by the end of the week which will allow me to test the functionality of the dryers.