I’ve been looking at tweaking my SPD a bit. I’ve found some pretty robust peristaltic pumps I feel would work as a discharge pump (to replace boiling flasks). Some of the ones I’ve found have all the bells and whistles when it comes to heavy duty spring rollers.
Correct me is I’m wrong, but isn’t the main reason gear pumps are used in WF is because you can apply heat? Would there be an issue other then that for using a peri pump like vacuum leaks?
If that’s the case, what about adding a second condenser to preheat on the downside before the pump?
They don’t work at our ranges. They are good for feeding mild pressure but they will collapse the hose and assembly that rolls. I’ve done it with a few and gear pumps with check valves work the best.
I just talked to a company here in Michigan that makes (up to 16 channel) peri pumps.
That was their concern.
But, why wouldn’t just swapping out the hose for a thicker ID for the rebound to work? They said they ran a hose (can’t think of the name) that they hit with 1micron that never collapsed or leaked and was food and solvent grade at 120c (canola oil).
If this was the case, then that should be the only caveat that can be solved, no?
I can’t verify this but I would suspect the problem with the hose becoming thicker and more rigid is you lose a lot of ability to pump because the pump itself is unable to squeeze the tubing and thus loses out on the ability to perform.
I may be wrong but just thinking about how a peristaltic pump works, I would imagine there is some sort of correlation between the thickness/rigidity of the tubing and the pumping ability/efficiency.
I mean I’ve done it. And I’m telling you it’s problematic and stops working even if it does. It creates so much tension on the rotational geared assembly that the hose turns into a rubber band and burns up the motor in no time.
It’s easier to pump from a atmosphere onto vacuum using a pump like that. However vacuum to out the issue is the rotations aren’t fast enough to really keep air molecules rushing backwards beyond 200 micron generally. I tested this big time even with solvents. The gear pumps rotate faster and prevent molecules from rushing back. The tollerances are alot better as well.
So, if I could find the tubing (which they have) that won’t collapse under vac, rotated at a high enough RPM to keep the gaps in fluid to nothing, and had enough force exerting on the rollers, I should be good then, no?
And shit… I’d replace the hose after every run regardless. Same as I do my vac oil. The savings is negligible at that point between the solvent, algonax, and my time.
You’d be shocked but yea that’s how much they cost. I can get you one with a custom drive for the same price. It’s just how much they cost. You don’t fuck around when it comes to quality. I got them with trace line heat plumbing built in with ports.
Ya know… a lot of people blow you shit. Watched people slag on ya for things you’ve said.
Never liked a comment that was derogatory towards you. I don’t roll like that.
Thought it was a reasonable conversation on learning about these pumps then terphole had to jump in and be petty child with his snide comment and you liked it.
I don’t have any experience with a peristaltic on an SPD, but tried a few experiments with a peristaltic on the solvent flask of a rotovap under vacuum. What I found was that a 3 roller peristaltic allowed a lot of backwards flow/reversion to happen, moving liquid back towards the vacuum source, which slowed output considerably from what I saw from that same pump when it was pumping liquid from even pressure zones. I suspect to get descent flow characteristics you would need at least a 6 or 8+ roller pump in either application
With thicker tubing you lose some amount of flow, but it’s not like an SPD output pump needs to move a ton of liquid volume in a short timespan. For what I was trying to do to empty a team of 6x 50L rotos, a 6+ roller peristaltic that used 1" or 1.5" tubing was cost prohibitive, but smaller units with a higher roller count should be more affordable, downside is that you may run into a problem where the motor/gearbox affixed to it isn’t sufficient to pump against vacuum at 100% duty cycle, and using a VFD to slow down a motor’s speed also typically slows its cooling fan which means more heat which isn’t good for the drive motor’s longevity.
I think Elliot is completely wrong claiming that the low speed that peristaltic pumps operate at is the reason that they can’t maintain operation under vacuum, it’s all about tolerance and whether the pump is completely closing the hose opening or not. If you have to crank the RPMs way up to maintain vac levels I can only think you’re using the wrong tool for the job.
I was using 3/8" silicone brewery tubing in my pump and didn’t have problems with it collapsing under vac. I would expect that the larger diameter you go, the less selection and more $$$ you’re going to have to pay to get a thicker walled tubing that’s suitable for what you want to do.
I’m afraid I don’t have any recommendations for brands to try this out, what you want is something that’s really overbuilt for your application, both from a motor HP and gear reduction standpoint as well as a rigidity/frame/industrial usage standpoint.
I do agree that $7k for a relatively tiny gear pump with a high NPSHR value seems insane.
Just so we are clear. There’s a shiny asshole side to me. Sometimes I like things I feel are sarcastic.
The wasted money and failed attempts to create the same effect from a proper pump made me realize without any issues o should just use a pump. O mean I had some sucess but those pumps I couldn’t sign off on bc there was some short coming somewhere. Instead it is a bit obvious that if you don’t Wana use gear pumps maybe glass flasks is best.
I’m not insulting people. I just saw that comment with snarky sarcasm. You’ll find people can like things and still be normal people.
I’m new to all this (not SPD, just the pumps). I thought it would be a cool concept (less clean up, less glass to break, straight to the liter jars).
I get what you’re saying and after researching more and seeing the size pumps available, I believe it can be done. Just matching pump size reduction (for torque) and a hose thin enough to “squish” to keep a seal. Running a second condensor prior to the pump to thin out the oil and add heat to the tubing that should allow it to be more flexible.
I’ve never been one to pay the “green tax” on equipment that was used decades before. Just a few tweaks here and there and just about anything should be adaptable.
I’ve gotta line on a few pumps that have the reduction drives, high tension sprinted rollers, variable rpms, and I’ll be checking out tubing this weekend.
I’m pretty sure it would work with the right combos
