We recover through the liquid line of the solvent tank. This way the recovered liquid hits a condensing coil, chilling it before it reaches the tank. On the gas side of the tank we keep a c1d1 air compressor driven vac running to constantly scrub out the head space which is where your nitrogen is building up. This generates a flow going into your solvent tank which eliminates the use for a recovery pump. Just make sure your pressures are higher in the collection pot then in the solvent tank before opening to recovery. With that vacuum running it should create a vacuum in the solvent tank. How cold you can get that solvent tank dictates what solvent you can use without boiling it off from the vacuum. While doing this you need to keep in mind how cold the tank is vs temp that your solvent boils off at vs vacuum pressure. Obviously Butane is going to work best with this if you can’t get your temps that cold. We use isobutane for now but are currently building out upgrades to switch to propane. We rock PRVs everywhere that can be locked down with pressure inside, all manifolds, material columns, solvent tanks, collection pot… Working in 502 in Washington means that if you wanna make changes to your extractor means you have to apply for the change with the LCB, submit your plans to be approved by and engineer. Then after your plans are approved by the engineer you have to schedule an inspection before operating with the changes. Makes upgrading way more expensive having to get that engineer stamp of approval and takes a lot longer having to wait for the approval and the inspection.
The reason I bring that up is that a lot of people seem to think that if something has an engineers stamp of approval that it’s inherently safe which is absolutely wrong. While working in a heavily regulated market like 502 I’ve seen countless examples of dangerous equipment being approved for use by engineers, fire marshals, LCB agents… Its pretty apparent that at this point regulation causes all these hoops to jump through not for the safety of the business but for another way to generate income for the state.
Remember, Safety first… then teamwork.