how does nitrogen assist closed loop operation?

hello, i see a lot of nitrogen being used to flush butane out and well... in also.

molecular weight is about half of nbutane. is it used to pressurize butane from the recovery tank? since it's lighter it will sit above the butane? why do i see nitrogen being pushed in the system after a run? is it to reduce the risks of venting butane by replacing oxygen or something?

WolfWurx's turnkey systems inject nitrogen once the butane has been recovered to -22" Hg, so that when the high vacuum pump pumps off the remaining vapor, it won't be pumping flammable gas.

Would pressuring passive system with nitrogen decrease transfer times? Increase yield? Increase polar components in resultant? How might this affect terp count?

Pressurizing would ostensibly raise the solvent boiling point and slow down the process.

No immediately obvious effect on monoterpene levels that I can see.

Nbutane does flavanoids better than terps. I've never heard butane for targeting terps. I've heard co2 @ 50C, hexane, and soy. Maybe you guys know somerhing I dont?

How hard could I vacuum in theory? What effects might be seen with extreme vacuum pressure? Up the wrong tree?