Im not sure if i even have a problem here. Im just getting away from harbor freight vac pumps.
I have a recently acquired Trivac D2A which is a big step up. Multiple oil flushes and im down to 7 microns on the bullseye and it moves air pretty well. I feel like it has more left in it.
Im using KF25 to super glued NPT 3/8 to stainless steel braided 3/8 ptfe hose. I would like some long hoses with 4 splits, is this a bad idea? This is only for 3 vac ovens, i dont need the CFM
With an inlet filter attached I can only pull 250 microns and it takes a while. Im assuming i have a leak or is this normal for the pump not blanked off?
Anyone used these? Im more worried about chunks than moisture.
7 micron blanked off sounds a little high for that pump but then again 200 micron is fairly high vac for most vac ovens. NPT ports leak like a sieve under vacuum without very special precautions and a good deal of voodoo. FYI most cheap PTFE will outgas a lot too and the CA glue even worse but I doubt that’s your issue.
KF bellows are the superior option unless you can hardpipe with welded tube/KF or CF joints.
Also, what do you need 200 micron in a vac oven for anyways?
Should the one way valve on the pump hold pressure over time? I take it i should address that first.
Ill probably end up cracking it open and checking out the innards further rather than flushing it to no end. Ive already opened it up and its coated in rust.
Because i dont know what im doing, figured it was helpful for shatter. I am still learning for sure. It seems to help with the cooling under vac phase of drying sieve beads too.
I also use it on columns before extraction. I figured higher vac would pull more moisture and terps
I should have started with this. The idea is to get the vac pump outside and far away in a safe place for off gassing. I guess i should have a different pump closer to the lab for that stuff.
Those harbor freight pumps seem to like to smoke like a freight train. Operation clean up the air is in effect. The TriVac with the exhaust filter works like a charm. Still smells a little funky from the previous owner… At least it was used for distillation.
How low should the pump go? The mfg website gave a large crazy Torr number that I converted (probably wrong) to sub micron.
That pump should be capable of 1 micron or less blanked off (1x10^-3 torr aka 1mtorr aka 1 micron). Rust on the inside means you got a bunch of water in it which isn’t surprising if you’re using it to dry media out without a cold trap.
What happens is if you have water or solvent in the pump/oil, as it pumps down those volatile compounds boil inside the pump. That obviously raises your vacuum level but they need to be compressed to atmospheric pressure in order to leave the pump. That compression causes them to condense and stay in the oil. Your ultimate vacuum with a rotary came pump is usually the point of equilibrium where the pump is boiling and condensing everything it can in a circle. When clean/dry, it’s actually the oil that is doing this.
As far as how much vacuum you need, try this handy dandy tool: Boiling Point Calculator
Using it we can see that water boils around -37C at 250 torr. I imagine your oven is set a little bit warmer than that so you don’t need that much vacuum.
Generally, I would recommend using a different pump (preferably something without oil because of backstreaming concerns) for your vac ovens than what you use for SPD because inherently you’re sucking junk into your oil when purging.
Vacuum pump oil doesn’t back stream. It’s nearly impossible. And people been spreading this myth for a long time.
Vacuum pump oil requires several times deeper vacuum and extensive temps to self boil and back stream. You might be refering to terps and contamination that lines the vacuum lines self boiling out.
Trust me nothing we do on cannabis really would cause any pump oil to back stream. Unless you were using junk motor oil and such.
On vacuum processes back streaming would ruin most processes and vacuum pumps that back stream molecules would be useless.
Back streaming oil is a myth. It’s water, terps or similar items that line your hoses that “might” cold boil
I mean to clarify the effect isn’t capable with cannabis unless you have a sterile system and decades below 1 micron and the oil is so shitty it’s cold boiling. Typically it’s nearly impossible and it’s other things that create that effect on tubing and such.
Hi,
it will stop the oil from sucking back into the vac line when you turn it off, but it is not meant to hold high vacuum. Are you not valving your oven off after you pump it down?
Also do like @SidViscous mentioned, protect that pump with either a cold trap or a desiccant trap. Rotary vane pumps don’t like contamination.
I apologise for misappropriating the term backstreaming. I was talking about sucking the oil back out of the pump if power is lost (suckback?). Was not sure if that pump was equiped with an anti-suckback valve
Until we got our dry pump I had it tattooed on the door of every oven: “YOU MUST CLOSE THE VALVE BEFORE TURNING OFF THE PUMP”.
Even with a pressure switch controlling a solenoid to protect against it, the idea of 2 quarts of type 19 coating our slabs still generates substantial “pucker factor”.
I once saw a $1.2M gold plating on the inside of a massive Alcatel deep vacuum chamber get misted during roughing for a leak test because they didn’t install an anti-suckback valve. Ended up not hurting anything but holy fuck did everyone in the shop for it fear for their lives/jobs. I was happy to just be the kid that installed the o-rings that day.
Dude, PTFE tubing is not suitable for vacuum. Crazy Glue is even worse. You need either gummy vacuum tube or thick PVC steal braided. No glues, just regular worm clamps. Must clean all that crazy glue residue or throw out the adapter and get a new one, cuz its probably gone. I can ship you the tube and clamps and the adapter https://labcradle.com i don’t think i have tubing listed on the website, will do it tomorrow before end of the day.
The super soft natural rubber seems like a good option, i wasnt sure of its leakiness but it seems like the best option for me wanting to cover long distances.
Ill probably order the soft rubber hose and go that route unless anyone has any objections. Im going to ditch the ptfe and super glue!
I will be putting a valve on the vac pump.
What kind of valves are people using in high vac? Swagelok? Trying to keep it at least 3/8 diameter
Thank you so much guys. I know its a very beginner problem. You guys are my knowledgeable friends network!
Any natural gas brass valve will do the job or good brass water valve, not necessary to have expensive swagelok. If valve doesn’t leak water it will not leak air prefer made North America.
This is not even remotely correct. Not saying you can’t use a watts ball valve but it will leak. A lot. In fact, any valve you will get will leak a little under vacuum, by how much is a function of design and materials.
well under this pretense everything will leak and nothing is 100%. good water valve may reduce your vacuum by 1micron and swagelok by 0.5 micron and it is $7 vs $30, does the cost justify the result?