I was trying to get a better look at the adapter you used to join the GL-18 port to your KF-25 hose in your pictures. My glassware has GL-14 ports, and I’ve been using a pretty extensive workaround to join them up. Where did you find your adapters?
These are probably the one he was using: https://labsociety.com/lab-equipment/glass-thread-adapter/
Honestly the PTFE adapters don’t hold up to the heat very well, I probably wouldn’t buy ours again. We’ve held better vacuum with thickwall tygon right over the GL threads
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I read that last line and died. Got me to post my first post! Great job on your run.
Yes they do. If you are referring to the quasi ptfe adapters then yes. Those are i section molded and generally really fucking shitty. We use bullet cut ptfe adapters and they hold up to vacuum and leaks very well.
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Do you guys make GL adapters or just taper joint adapters? The latter are much superior IMO.
I still think this is the correct way to adapt to KF from glass but it’s a bit pricey:
I’d love to see some of the higher end manufacturers start using them and eliminating the PTFE entirely
Well to be fair this is a horrible idea bc tapering down just cuts off cfm. There’s literally no purpose to run a bellow setup direct to a gl barb glass apparatus.
We do male stainless to barb attachments Wich is better than the glass to metal . Glass to metal is for stationary work. It is extremely unstable and cracks off easily.
Thank you, that’s good to know. I still would’ve gotten some if they had them in the right size.
I’ve been chasing a vacuum leak in my system for about three months, and have tried replacing or bolstering all sorts of different components without much improvement.
I have a KF-25 bellow hose bridging between my vacuum pump and a 24/40 port on the cold trap. But I’m using ptfe tubing between the cold trap and the monocow, and the condenser head and vacrometer because of the GL ports.
I’ll check into the Tygon tubing.
I want to make note that I have gotten the vac down to as low as 140 microns, but the gauge always bounces up and continues to rise after the system reaches its lowest pressure. I have assumed that this means the vacuum pressure has become low enough to exploit a weak joint and begin pulling atmosphere into the system. Is that the case, or is there usually a parabolic action when pulling a vacuum?
I assume you’ve tried spraying your joints checking for leaks? Does your vacuum ride high while stripping and continue to rise through mains? Does it ever settle out within a few micron through fraction towards tails? Just curious Ive encountered similar issues.
Wish I could tell you how a legit run has gone for me. Unfortunately, I have not been able to maintain a stable vacuum reading during a dry run, and therefore have not proceeded with loading up any material until I can isolate the cause of the leak.
I’ve tried wafting smoke and helium around my joints, but haven’t tried spraying them with any kind of liquid. Perhaps I will try that, too.
Can anyone else answer whether or not it’s normal for a vacrometer to fluctuate well above the lowest recorded pressure? Could this be an issue with the vacuum pump encountering a maximum resistance and then wimping out or something?
If helium didn’t show in vac then it’s probably not your joints. Have you isolated just the pump and guage to see if it’s indeed the pump failing?
I’ve tried blanking off in several different ways and have had trouble definitively ruling out the various components, i.e: two types of PTFE tubing, with and without Teflon tape, with and without hose clamps, on two different vacrometers.
The only time I was able to reach and keep a decent vacuum when blanked off was when I attached the vacrometer to the pump with a 1/4” braided metal hose—that maintained a depth of 165 microns.
I’ve suspected the hoses are the culprit, but replacing them or adding other hardware to them hasn’t yielded any consistent results.
I’m sorry if I missed it in the thread, but how many cdm is your pump and what size sp do you have?
I’m using a 12CFM vacuum pump (nothing special/junk pump) on a 2L SPD apparatus.
I made my first post in this thread. I’ve since made improvements to the setup by reducing the amount of hose and purchasing a new wide-bore cold trap that connects to the vacuum pump with a KF-25 bellows hose.
https://future4200.com/t/newbie-any-recommendations-spd/13080/24?u=mar_bloodgarden
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Yep, you aren’t far away from a great run. I looked at your pics. I have to agree with some of the posts expressing the need for large diameter hoses etc. It does make a difference ime. Also I noticed your vac guage was hanging down from your cold trap. I did that once and when my trap thawed I ended up with terpy disty clogging the guage which affected my readings. I read on here that one should always have the guage upright and if possible before the cold trap. Im new at this so I just keep reading and trying new stuff. You will get there.