Short path vacuum

I’m fairly new to all this. Learned everything from someone else who learned from a garage guy…. We have a 2L short path system setup from BVV I have reset cleaned re greased and retaped all my components and cannot get a vacuum under 800 microns. I have never had this problem before. I have changed the oil checked hoses played with temperature and the spin bar speed. I’m at a loss and am ready to just quit. Using DOW CORNING high vacuum grease. Dry ice and 200 proof ethanol for the cold trap. BVV 56 industrial vacuum pump. BVV poly science recirculator for the condenser head. Is it the garbage crude that’s being run causing the vac to not run correctly? Usually I am able to run perfect body at 200C on the mantle pulling 165c in the condenser head vape temp. And pulling a 120 micron on the system. Please help.

Not sure how to respond on the texts you sent so I am adding here. I use the food grade pvc hoses it’s stiff but pliable with wire wrapping around hose inside for stiffness. It might be the product but I’ve pulled a lot of volatiles already. I took the whole thing apart to clean again and just changed vac oil. I will get back to you all after I run it again today thank
You all for your input.

Not fully decarbed? If you’ve ran successful runs before there’s only so many possibilities

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Very annoying. Your first task is to figure out if you have a leak or if semi-volatile contamination has built up in your system and is fighting your vacuum.

Can you isolate your vacuum to test its levels in isolation?
Then can you isolate your cold trap?

Did you vacuum test the system before adding material to the boiling flask?

Is there anything smelly coming out of the pump?

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How often do you change your pump oil?

Turn the lights down in the room and run a flashlight over the spd and all the connections (joints and gl fittings) and see if you notice a vapor stream after any of the connections.

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This is gonna sound nuts, but check your vacuum hoses. Make sure one of them is not collapsing under vacuum. I’m assuming on a 2L you’re using gum vacuum lines. I had this problem a couple months ago on my small still. Drove me nuts figuring it out.

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Chasing a vacuum leak is tedious, but pretty straight forward.

Start with the pump, put the gauge on the inlet and deadhead the pump. What’s your vac level?

Then, if that’s ok, move to the next fork in the road. Isolate the system from there back to the pump and get a reading. Still ok? Keep going.

Keep going through the entire system to isolate a leak.

Too much grease works against you at some point, go easy.

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For sure start with an empty system, grease up your joints and see if you pull vac. If not, it’s not a material issue.

Next I’d look for hoses (sometimes they fray at the ends, cut them fresh if they do).

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Thank you everyone!! It was a vapor lock in the neck. It took days to go through everything and a simple heating of the neck fixed it :melting_face: