passive vs active: recovery times

ok so I've been running active for about a year and a half, and the whole time I've just been working on ways to get faster recovery times. I sort of understand the basics of passive but wouldn't be able to run one or anything. what I'm really curious about is recovery times...I see people on IG claiming 1.75/lbs/min easily, I see other guys claiming 2.75-3/lbs/min. if thats the case why would anyone even run active? are there larger down times in between than with active? I'm hitting about 1lb/3min. so going passive sort of sounds appealing...what say you...??

gumby420 said:

ok so I've been running active for about a year and a half, and the whole time I've just been working on ways to get faster recovery times. I sort of understand the basics of passive but wouldn't be able to run one or anything. what I'm really curious about is recovery times...I see people on IG claiming 1.75/lbs/min easily, I see other guys claiming 2.75-3/lbs/min. if thats the case why would anyone even run active? are there larger down times in between than with active? I'm hitting about 1lb/3min. so going passive sort of sounds appealing...what say you...??

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I say I would like to see the details of how they are accomplishing those numbers. Passive recovery is a function of evaporative area and condensing capacity. The larger the evaporative area and the greater the condensing capacity (more area or more delta T), the faster the recovery.

Ive been running passive for the last 2-3 years. i get about 1lb per 5mins with straight dry ice....i can get slightly faster adding iso or acetone but 3lbs per min seems stupid fast. I wish i could hit those numbers but i only run max 7lbs of gas so 30-35 mins of recovery time is not bad.

I think if i increased my hose and fitting sizes to 3/8 or 1/2 i could further decrease recovery times but why break something thats been working perfect for a while

I think the insane recovery times we hear of come from liquid co2 being used in jacketed tanks as opposed to using dry ice. Also, not that I can speak from experience yet, but I have read over and over that increased hose sizes significantly help with recovery times.

Well if you get even AS cold as dry ice (actually warmer), your butane will turn to gel, so you don't want columns that cold. An injection coil/heat exchanger on your line-in might benefit if it were it were undersized. But if it were big enough, DI/ethanol/acetone is as cold as you SHOULD have to get. But sure, there's times where you want to chill something hot FAST. Also, I'm not sure what temp propane/blends can get.

Apparently, propane can get 48°C colder, with a listed melting point of -188°C. Although butane is listed as -140°C, people seem to have problems getting it to flow properly at around -60°C. So perhaps propane can get down to -100-110°C. Dry ice slurries can get down to -78°C. Still, I'd be cautious getting any large vessel below -80°C because those temperatures can make steel brittle.

Regarding the OP, remember that in a properly configured active system, youare *also* doing the same heating and cooling as a passive system. It's not necessary to do that to such a degree as you would with no pump, but you *can*. And because of this you could say that basically any active system would run faster than a equivalent capacity passive system, provided it heats its collection vessel and cools its recovery vessel and/or coil the same amount.

Pumps are just one part of the equation. There is a certain amount of energy that needs to be put into and removed from the system. Temperature control is one way, a pump is another, generally used in whatever ratio meets the needs of the user. Could a really well built passive system with powerful heating and cooling beat a poorly built, underpowered active system of the same capacity?
Sure.

Itsgotatail said:

Regarding the OP, remember that in a properly configured active system, youare *also* doing the same heating and cooling as a passive system. It's not necessary to do that to such a degree as you would with no pump, but you *can*. And because of this you could say that basically any active system would run faster than a equivalent capacity passive system, provided it heats its collection vessel and cools its recovery vessel and/or coil the same amount.

Pumps are just one part of the equation. There is a certain amount of energy that needs to be put into and removed from the system. Temperature control is one way, a pump is another, generally used in whatever ratio meets the needs of the user. Could a really well built passive system with powerful heating and cooling beat a poorly built, underpowered active system of the same capacity?
Sure.

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ya I run my active system as I would a passive at least to my understanding. basically just high psi in the collection pot and low psi in solvent tank. but I know for a fact these two particular guys I'm talking about do not have crazy passive systems and are not running liquid co2 like a bizzybee system.

gumby420 said:

ya I run my active system as I would a passive at least to my understanding. basically just high psi in the collection pot and low psi in solvent tank. but I know for a fact these two particular guys I'm talking about do not have crazy passive systems and are not running liquid co2 like a bizzybee system.

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Maybe thats my issue as well....Im running 100% butane. I try to keep my collection pot as close to 80F as possible without my pot freezing over....i might start off at like 92-95F for a minute or two.....but then its right down to below 85F for the rest of my recovery.

I dont see any pressure higher than 7psi typically and that might be the highest psi i ever seen.....Im sure if i had my tank in 150F water for 3-4 mins i can pass the gas WAY faster but with the consequences of possibly burning my oil. Im sure if your making distillate after this wouldnt be a problem but Its really easy for me to pass 7lbs of gas inside of 30 mins with minimal heat and my recovery tank in Dry Ice with either 99% iso or Acetone really whatever i have an abundance of at the time.

I think my stainless tank transfers the heat/cold much better than my carbon steel tank as well with recovery times as well...major difference with that change. I can understand the need to move the gas super fast but isnt that when mistakes start to happen.

Maybe im just too lazy or need time in between runs to set up ovens and paper....clean out my tubes....take dabs...walk the dogs...eat....etc. LOL

i think im just lazy...i happy to be able to extract 2lb per hour with cleanup and set up for the next run. Thats enough for my habit.