We run both pirani and thermocouple style sensors on our vacuum trolly.
Not sure if both those vacuum pumps are hooked up, but seeing them reminded me of a lot of people mentioning auxiliary pumps. What is the purpose of running two pumps during a run? Or am I misunderstanding their use?
One is for backing the diffusion pump, the other is meant to rough down the system before the diffusion vacuum pump can be turned on.
Did you make the cold traps. Think I’m gonna make some stainless traps like bhogard. I like the big one. Did you repurpose those?
made all the stainless, originally the traps come with glass cold traps.
I just finished up my high vacuum gauge/controller. Its probably 4 or 5 on the diy difficulty scale, but it works great and has better features then the expensive name brand controllers. Here’s a few pictures of the setup. I use an arduino mega and some mks 901 active micro pirani sensors. You can pick up the sensors on ebay for $40-$60 all day long. It currently can support 2 sensors and can switch on or off equipment if you want it to. Although, i’m not sure why i added that feature. I dont think ill use it at all. I’d be willing to post a small write up if people are interested. I’d also be willing to release the alpha code for anyone that doesnt have coding skills. The alpha code only has support for one sensor and no error handling. Really basic, but should be enough for most peoples needs. I dont have time to do a full how to, but i can try to answer questions as best as i can.
i personally find this super interesting. I already have a bullseye and im interested in a writeup and would actually like to build one. This is right up my alley. What did you write the code in? I have some experience in VB and C+.
After running my distillation setup yesterday. i relized the importance not only to know what pressure your pulling on the vac. but know the vacuum of the system would be sooo helpful. I now know why i see these bling bling distillation setups with mulitple vac gauges.
Please do a write up and if i can help or make one id be happy to do so as well for the community…This is super bad ass.
Please do a write up!!! I was a comp sci major and can code fairly well in quite a few languages and would love some of the in between steps for this!
The vacuum gauges beyond the HVAC digital variety are way too expensive, please share in as much detail as you can. Maybe someone will assemble some for a reasonable price for those lacking the technical proficiency, like what was done with e-nails when they first came out.
I’d buy one in a heartbeat
I think if somebody could find or post how to interpret the serial code from the MKS 901P then you could even use an old ass computer / laptop to just watch the data on the serial in realtime. On a computer it would be easy to have it dump the data in a spreadsheet and show a real-time graph.
Hè soxhlet Nice setup 
I was wondering would a one stage leybold b25d be an option as pump before
I go for the cannabinoids
So say till 160C head temp on a one stage 15cfm and then over to a diffusion backed by a 2 stage 7 cfm
Or would You swap the pumps
Or only work with a 2 stage roughing and baking. Pump
Thx in advanced
If the ultamate vacuum level is approprite it should be just fine, cmf is a moot point once their isn’t any air left to move. I usually watch the guages, once the vacuum improves and the head temp is right I know their arent any volitiles left to strip. I set the mantle back 20*c then throttle on the diffusion pump. Then I creep back up on the heat to start the canabinoids coming over.
Maybe not the right spot for this but
I really start believing that the faster vapor is condensed or removed from the system the lower the average vacuum of a proces
Several by accident story s here on the site Where what seems an overkill of pump cappacity Some how gave better results
Thats how @anon42519203 was doing his, mabey he can chime in.
Once cfm flow is gone molecular flow comes into play, the name of the game is pushing molicules tward the mechanical pump and out of the system. Diffusion and turbomolecular pumps are used in UHV systems specifically for this purpose. An array of mechanical vacuum pumps may work in a slightly similar way, but not as effectivly as the turbo or diff pumps.
https://www.pfeiffer-vacuum.com/en/know-how/introduction-to-vacuum-technology/fundamentals/types-of-flow/
I’ll do a write up sometime this week and post the basic code. The arduino uses a wrapper around c/c++. Its very easy to learn and if you have any c/c++ experience you should be good to go.
Yes, the mks 901 uses a non handshake rs232 or rs485 protocol depending on the sensor features. You can definitely hook it up to a computer and not have to use the arduino. In fact that’s how i initially tested the sensor. The documentation on mks 901 is pretty good.
I already ordered an arduino mega kit to learn it and I’m sure it will come in handy for other tasks (I would like more control over the PID). A lot of good cycle timers or automation systems are significantly more than an arduino.
I’m guessing you can just take apart a DB15 cable and then use a multimeter to tease out the leads and hook it straight into the input pins on the arduino mega.
No, you can’t hookup the hd db15 directly to the arduino from the 901. The arduino uses ttl serial and the logic voltage is incorrect for true rs232 communication. You need a converter. I used a MAX3232 from sparkfun to make the conversion. The breakout board they have will allow for 2 sensors.
I got my arduino kit and I’ve played around with it a bit. I’m stilling waiting for the max3232 and the 901k… Oh yeah and the kf fittings and such to hook it up! It seems like these projects always have so many pieces 
I could see how you could make a super PID with the arduino pretty easily and it would be about the cost of a PID I think. You’d just need a solid relay.
