I’m running a lyphan roto 2L with gg-13 glass. When I put vacuum with my shz-95b water aspirator pump on it(80L), it pull full vacuum into the red on this shitty default gauge. I’m worried about implosion and don’t want to lose product. The first 2 times was fine but I’m not sure if this is a ticking time bomb. Is this too much vacuum?
It stops right before -.1 (I do not having it running filter atm)
Get a an adjustable vacuum relief valve
I use one of these, it works, but it’s pretty sensitive- you’ll learn to fiddle the twiddle though
you worry too much…
you will be hard pressed to implode your glassware by sucking on it with a water aspirator. I’d state it was impossible, but with damaged glass you might be able to manage it.
even using the biggest pump he could find @BrotanicalMatt couldn’t manage it
too much vacuum on your rotovap is a functional problem. if you suck too hard all your shit boils over and fouls the condenser.
if it’s not boiling too hard, you’re not sucking too hard.
Okay thank you for the quick responses… I’m over her feeling like I got a live nade in my hand. Appreciate it!
It’s the differential pressure that makes glassware implode. In that sense the difference between a 1% vacuum and a 0.1% vacuum actually doesn’t make much impact. You’re more likely to break your glass in the pump down and if you’ve made it that far kicking on high vacuum isn’t likely to do much.
If your ETOH boils and condenses at room temperature with your chiller at max, then you are pulling plenty of vacuum.
If it boils up out of the globe, then that is too much vacuum.
If you are skeered, there are several spots (knobs) on the roto to bleed it from.
You want to run it in the red all the time.
If you are still skeered then wear a heavy lab coat and a full face shield.
As most have said, you’re most likely not going to implode glass with a water aspirator. The thing to really pay attention to in this instance is bath temp, it’s unlikely but if it spikes for whatever reason you may encounter bumping and foul the downstream system, this would mostly just be a huge pain in the ass than anything else.
Also, you want to ensure you’re not boiling more ethanol than your chiller/condenser can handle. A side note to that would be to make sure you’re using the right transfer fluid in your chiller, most folks set their chiller for the coldest temp possible, but if you’re using the wrong fluid it may increase in viscosity and will not be pumping through your condenser efficiently.
