Using DigiVac Vacuum Gauge with Vacuum Oven

Does anybody have the issue when using a DigiVac gauge on their vac oven that it’s not “catching” the vacuum reading quick enough?

I find that after I’ve already pulled an initial vacuum, and come back later to pull even more vacuum that the gauge doesnt pick up on the vacuum level immediately/quick enough for how fast the pump is pulling.

Example: I pull initial vacuum to 20,000micron and then close off vac. Then if I wanted to pull a vacuum to 10,000micron later when i go to restart the vacuum (1min or even an hour later) the vacuum gauge starts at 900,000micron and works its way down to 10,000 micron quickly, but by the time i’ve actually reached 10,000micron i’ve actually blown right past the 10,000micron because it took too long for the Digivac to give me the reading of 10,000micron.

I hope this makes sense and if anyone can give me some inisight as to how to use the guage better that would be greatly apprecaited.

The Bullseye was made from High Vacuum applications. I believe they say about 1-3,000 micron. The sensor reads much better in that range compared to the lower vacuum range (higher value). It takes a bit initially to read at lower vacuum levels. That’s why it jumps down fast, the increments it reads in are much further apart. The jump from 20,000 micron to 900,000 micron is probably from a small leak somewhere in the system.

If you need some kind of vacuum regulator JKEM has a DVR-200 that can control to 1 torr or 1,000 micron. That seems like the right range for this application.

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Using an 11.3 CFM 2 stage rotary vane from BVV. Are most people using a vac controller with their vac ovens?

what gauge do you use with your vac oven?

Pressure build up from the escaping solvent? Are you using heat?

I may have mispoke in the initial question.

When I close off the vacuum oven the vacuum is still pulling vacuum on the tubing from the vacuum to the oven, so it goes down to it’s ultimate vacuum quick. At this point ill turn off the vacuum. When i go to restart vacuum later on it actually starts from a low point of 38micron, and when i open up the oven to engauge vacuum the gauge begins to go up to the current reading. If I’m trying to go from 20,000 to 10,000 micron (it only takes a few seconds) by the time the gauge is ramped up to the vacuum reading of 15,000micron , i feel that I’ve already passed the 10,000micron mark.

Is it the location of my gauge? it’s next to the pump vs inside the oven…

Install a bleed valve between the oven and the pump.

So currently what I do is similar to what you may be suggesting, to go from 20,000micron to 10,000 micron I’ll bleed air into the oven so I’m well above 20,000micron. Then Ill engage the vacuum so it gives the vacuum gauge enough time to catch up to the vacuum level. I was looking for a way around not having to bleed the oven to get an accurate reading.

I find that the analog guage that comes with most vac ovens are worthless for accuracy.

Accuracy for what exactly? I find in.Hg more than informative enough on an oven. Don’t need even mm.Hg accuracy to get purging done right…

um.Hg level precision is for when you’re trying to volatilize your cannabinoids, not remove solvent that boils at 0C.

Ymmv.

You should really be using a diaphragm pump for this application. Just a note.

I find that of the 4 ovens I have, each one shows a different value on the analogue gauge when pulled to the same value on the digivac guage. 4 to 5 in Hg difference. They all show the needle going weirdly far beyond the 30inHg when pulled to “full vac” except on the AI oven, the other 3 ovens are from BBV.

Fair enough. I let what is in the oven tell me how hard I need should be sucking, and the gauge as a reusable number to get in the correct range. Helps to have the same scale and range as everyone else, but not an actual necessity to get the job done.

I have the same issue sometimes and though I haven’t pinpointed the issue I have a hunch.

Sometimes the readers don’t communicate together and it just messes up everything.

I just reposition the readers around the hose.