Anybody using a gear pump to constantly collect from the bottom of their solvent recovery flask and/or to feed their evaporation flask? Curious if so and what your results were. I’ve pretty much maxed out my roto with a preheated feed tank, a really powerful chiller and a pretty decent diaphragm pump so I’m looking for ways now to just hook up a 55 gallon on one side, a 55 gallon on the other, and just let it run without even having to look at it.
Just hook it up to another storage tank connected to the recieving flask and drip feed it.
It doesn’t really work because opening the bottom of the recovery flask will suck in air before the liquid will drain out, so you kill the vac to the system. I was thinking gear pump because it can opearte without breaking the vacuum.
Vacit down so there all the same, i have a 25 gallon keg hooked up and it drains just fine. Have it open in the beginning and it will all be just like one
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I took the receiving flask off and replaced it with a 15gal keg. Makes it a hell of a lot nicer to collect a full 15gal than 10L at a time
Install a valve to shut the keg off, another valve to break vac, and use positive pressure to push solvent out of a dip tube.
You can use another valve attatched to the manifold to get vac back down before opening the drain valve
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I tried attaching a 3 rotor peristaltic with 3/8" ID hose to one of our rotos when we were still running them for solvent recovery (we’ve since switched over to an FFE), found there was a lot of recursion/backflow and the pump was working pretty hard to drain a relatively small amount of fluid.
I think it could be improved by using a larger peristaltic that used a larger diameter hose at a slower RPM & with more rotors to minimize backflow against the vacuum, but price for those seems to scale very high very quickly.
Some gear pumps are well adapted to pumping against a vacuum - I’m a big fan of the ones on our BZB hammerhead - and some are not. From what I’m to understand they need to have a high NPSH value to avoid backflow/cavitation when pumping liquid out under vacuum.
A far simpler method would be to invest in larger holding tanks that won’t collapse under vacuum and put your roto on a pedestal so gravity does your work instead of an expensive pump. 4x 15 gal kegs and a manifold to connect them seems pretty cheap by comparison.
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Dual kegs would be boss mode, and way cheaper than a nice pump
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Yeah OP had just said something about doing a 55 gal drum all at once which is why I was thinking 4x 15’s
i used a peristaltic to feed and it worked great. A peristaltic to empty on the other hand did not work so great, it just backflowed air into the system (3 rotor). I’ve been told a 6 rotor might have worked better.
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Holding a larger volume increases vapor pressure and will diminish your potential distillation speed. The recovered solvent warms up and a portion vaporizes and hits the condenser and turns back to liquid. This process repeats endlessly until cooled or vacuum break. If you can cool the receiving vessel that recycling will be reduced which will allow more freshly distilled vapor to takes it’s place, allow it to fall faster without any uprising vapor to push against, etc.
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You don’t want a gear pump you want a circulating diaphragm
You’d be a lot more useful if you suggested a brand/model or linked to a site selling whatever it is you are suggesting, when you search for “circulating diaphragm pump” all you get are regular diaphragm pumps that don’t work all that well for pumping against a vacuum. Pumps like the Ingersol ARO’s are loud and use a lot of air - not sure if OP has that at their disposal.
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We sell a German pump, similar to a power steering hydraulic pump style. If you are interested Incan send you a quote for a pump skid that can attach to bottom of your roto. It’s the same certified pumps we use on our falling films.
@spdking, a hydraulic pump of similar style to an automotive power steering pump is not in any way, shape or form a diaphragm pump. I think you dropped this:
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A fluid diaphragm pump has a rotating cantered center axis. When it rotates it moves the diaphragm forward and back along in synchronized motion with the other diaphragms.
I think the term is swash plate.
Hydraulic pumps like a cars power steering pump are rotary vane or sometimes gear pumps, not diaphragm pumps.
Not all diaphragm pumps use rotary motion and a cam/crank of some sort to translate that motion into linear movement, the MVP would be a good example of one that does, whereas the Ingersol ARO’s use air pressure on the backside of the diaphragms to move them back and forth, they have no rotating element.
A swashplate style pump is used when there is a need to vary flow or volume independent of RPM, that seems needlessly complex and expensive for the application we’re talking about here.
I’ve pumped out under vac with a basic AODD diaphragm, just has to prime it.
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Thats the way to do it, i only use one but it works like a champ.
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yeah, I don’t believe I ever ran it this way. used one keg to feed, the other to catch.
however, once I realized I had two 6" mk III terp tops onsite, I had to at least assemble the required equipment.
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