Hi F42k community!
I have been making BHO in a closed loop (BVV) since 2016 almost daily. Recently got my first stainless steel recovery tanks and was able to finally replace the carbon steel yellow refrigerant tanks with 50# capacity tanks from OSS. My issue I am now seeing is my PSI seems way off for what the chart I am reading is saying 70/30 n-butane/n-propane mix is saying. @ 70F in the lab I have a resting pressure of 60psi instead of the 45psi the chart says it should be.
The whole system is OSS as the boss was on a budget for shopping. I am currently storing solvents inside of our blast room and the PRVs are set to 125F. I am really worried about pressure increasing during the heat of the summer months (can hit 95-100 a few days outside and blast room is unconditioned). Of course with my boss being cheap we do not have a C1D1 room so if this pressure is released I’m fearful that it may leak out of our poorly sealed room and ignite taking out the lab and his grow.
I do have an explosion proof fan, passive air intake, explosion proof lighting and air driven Venturi. Just no automatic air evacuation tied to a sensor.
I only have 40# of solvent in the tank so do not believe I have overfilled.
Only 10# of blend was used from the last system, the other 30 are fresh and have been topped off with freshly distilled butane a few times. From the first distillation pressures have been high once the solvent reaches room temperature. Recovery is right around 0 psi, passive through a coil.
Initial vacuum pull the gauges didn’t get all the way to -30in on some vessels but others did. Everything held during the pressure test so I don’t think my vacuum would have leaked. Was assured that the difference in the gauges was just an atmospheric difference since I am so far above sea level I wouldn’t show as deep of a vacuum.
It was suggested to me that my propane ratios may have increased but that does not explain the high pressure from initial distillation.
I get all my gas from Ozark in Spokane. It is possible the mislabeled a bottle 70/30 when it was 30/70. Yet extraction pressures don’t seem any higher than when I was using a 1lb system.
Running dried trim.
Any suggestions for a fix are welcome. Is this pressure acceptable? How can I fix this issue? Should I be trying to get a new gas supplier? Should I add strait n-tane? Did I mess up the initial vacuum on the tank?
Thanks all for getting me this far. Not sure if I would’ve survived without all your advice!
if you mixed it then trust your guage and the vpd chart and temp will tell you your mix minus stuff like nitrogen.im not sure but maybe 50 lbs water tank doesnt hold 40 lbsof propane mix? tanks are rated on water capacity not hydrocarbons.
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Na it comes mixed. The site says 51lbs butane specifically so I think Im good there. Also when I see the frost level its a good 1/3 down the side showing my solvent is not all the way at the top.
Pulling nitrogen off with a Venturi after every run so I don’t think its that. Even the first distillation with no nitrogen had a high pressure.
I bought a butane tank off bvv and the outside of the box and my reciept said ntane but the bottle said isobutane. Trust your gauges if they seem to work. bvv never responded to my query on why. thy never respond when thy send the wrong fittings either. I live near there and shop in person and its a bunch of wooks in cublicles so why cant they respond?
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vpd chart should let you know if its a mix or butane plus the small amount of mix he added. You have to trust the guages= science. I have 2 bad guages that start off saying 5 psi. I use them for observing differentials in the system= i gott replace hose with non bvv guages.
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I use up some each run. it gets stuck in the material and crc and gets purged and stuff. Id just run it and then get a new tank soon. I think they sold you the wrong mix but id use it and then replace.
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if you have a room then why arent the prv vented far outside? I moved to cold butane to avoid these dangers. the only pressure in my system is from nitrogen or a propane push into a cold tank
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TLDR; excess pressure in solvent tank = air. It’s air or N2
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Guessing air if anything. Possibly condensing at dry ice temps making it difficult to vacuum out. Any good way to get rid of atmosphere trapped in a solvent tank? Other then dumping 50# and trying again.
I would bet that the original gas you added from your tank was extremely propane dominant . This is what happens after a while of using blends and you just didn’t notice it in the carbon steel tank without a gauge .
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Seems like a few of these gauges are a bit off too, but the same amount off so it makes me feel a bit better.
Yeah burping the tank from a vapor port . Butane is more dense than atmosphere and the positive pressure will push it out
At negative temps Im guessing? I burp and then vacuum with a Venturi until reaching below 0psi. Normally boil a small amount of tane. Next try will be a top off with n-tane.
I thought the opposite and the propane was first to offgas? A 70 30 propane blend becomes more butane over the distillations RIGHT? each run is essentially a distillation right?
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@Chewwie just chill your tank and pull partial vac or room temp short burp vented outside @thumper n butane has the highest boiling point therefore gets left behind in the material and in your oil. Propane has the lowest and is the first recovered . Meaning your going to recover all your propane first and only lose nbutane
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Yup air in your tank. Vent outside.
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Ill have to review that when im not drunk= it 920 pm dammit. I thought the propane was most likely to offgas but I see what youre saying. In general im avoiding all that stuff and using ntane. Is there a difference on which gets more caught in the material= i probably should ignre that but at some point i thought cls meant CLOSED. now I off gas alot. I ran my forst hot loop last week and that worked well
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I highly doubt you have air in your tank because you chill your tank and pull vac to remove nitrogen . Unless you have a massive leak in your solvent tank or somewhere in your system . It’s still worth a shot to eliminate a possibility
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