Maintaining negative pressure during distillation

Hey everyone, I’m trying to run my CLS for the first time. I have a Mk3 Terpenator with everything needed to run it (bought it as a turnkey setup from the Terpp Extractors peeps.) Before starting the distillation process, I put the mk3 into a hot water bath (at 85-86*F which is what they recommend in Mk3 operating instructions) and the recovery tank into an ice water bath. I opened all valves on the Mk3 and then used the vacuum pump to pull the system down to a full vacuum. I then vacuumed the lines between the recovery pump and the recovery tank and brought those down to a full vacuum and then removed the hose from the vacuum valve. Negative pressure/full vacuum was being read on both the gauge on the mk3 and the gauge I attached (after vacuuming the line) to the coil/vacuum valve on the coil. When I started the process (i.e. introduced solvent into the system) to distill the gas from my n-butane supply tank to my recovery tank though, both gauges on the mk3 and coil started reading an increase in pressure (above negative pressure that is.) When I turned the gas off and then let the recovery pump keep running, the mk3 gauge showed that part being pulled down to negative pressure again, but the gauge on the coil continued to show a +20 pressure reading. Is this normal? If not, what might I be doing wrong?

I appreciate any help.

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So you were injecting butane and your gauge read 20 psi? Sounds about right to me.


Uhh if I understand correctly your system responded to the butane addition. Once gas has been added the pressure is going to go up, regardless of your previous vacuum atmosphere purge. Everything’s normal. 20 psi is very low, relatively to normal processing.


Ok, that’s what I thought but I wasn’t sure. Since it’s my first time running it, I wanted to make sure I was doing everything right and safely. Thanks

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This is certainly not meant as an insult, please don’t take it as one. But the level of ignorance it takes to ask this question is very scary. I worry for you my friend. Probably be worth your time and money to hit someone like @Killa12345 up for some basic consulting and some ground work on thermodynamics.


I’m glad you’re asking questions, but scared that you’re trying to run a CLS without even basic knowledge about volatile solvents. Closed Loop Systems are extremely dangerous if you don’t understand a wide variety of scientific principles.


Nobody’s trying to bash you, but you should definitely spend some time reading on here to keep yourself safe. I’m learning to man, this website is going to save your life, and wallet.


Thanks for the input everyone. I have done a lot of reading, and I also managed to distill all the gas I needed, had the proper ventilation with explosion proof fans and roof intake, I was constantly checking all seals/fittings/tanks with the combustible gas detector, and thankfully had no leaks. One of the techs at Terpp Extractors was also very helpful when I was able to get ahold of him.

Unless I’m mistaken (and genuinely correct me if I’m wrong), the main dangers would be overpressurizing, seals or fittings leaking, not using sparkless equipment or having ignition sources nearby, and not having proper ventilation, correct?


What caused that?

I’m not trying to be rude but you have to respect the able of butane to blow up your building, kill you and everyone one in the vicinity. Please precede with caution and stay safe.

It was just an image from a butane hash oil explosion

If you’re doing it illegally and lucky enough to live through the explosion then you get charged with meth lab laws and a bunch of other shit.

It does sound like you have a decent understanding of safety principles which is a good start. When you add butane to the system if its not well below its boiling point the pressure in your system will rise rapidly to positive pressure. The butane gas will fill the vessel. So to answer your original question yes its normal.

I always kept a fan running in the room as soon as i started dumping my solvent out of the column. 90% of accidents from BHO explosions occur from negligence. Simple things as not changing tape every time you undo a fitting and putting it back together. You should keep a VOC ppm meter inside the room at shen to ankle level. Butane is heavier than air so it will sit on the floor. This is some reassurance you have walking into the lab to know it’s safe.