Hello,
We’re having 2 separate problems with our Lanphan wiped film distillation unit currently. There are big vac leaks coming from our feed and discharge pumps and our condenser heater is leaking from the reservoir (slow leak) and having problems keeping the temp where it is set if it’s a more moderate temp.
Pumps- All 3 of our pumps (feed pump and both distillate and waste discharge pumps) have had issues with vac leaks.
We know for sure it is the pumps because we are able to remove them and plug the openings and when we do this the vac gets low like it is meant to.
How we have resolved this issue in the past is to pull the pumps apart and repack them with 3/16" teflon cord and slowly tighten the flange back down. The pics show the pump (all 3 pumps are the same) and where and how we packed it with the Teflon under the flange.
The problem seems to be that the packing never lasts. We keep trying to not over tighten the flange so it doesn’t get squished down/impede the shaft from spinning, but we keep getting leaks. We can usually run once or twice before they need to be repacked. There has to be a better solution to this.
Our condenser heater is also being a bit odd because it seems to heat to 80 fine and cool to 20 fine but it has an extremely hard time staying at 40 when it needs to be set there.
It also has a slow leak in the reservoir, which will be nearly impossible to fix since there’s only a small portion of the outside we are able to remove and the rest is one piece.
i don’t know if teflon tape simply cut will make the seal you want. i think you need some proper packing rings that are made for that, that join together into perfect rings around the shaft.
as far as the condenser–when you say it has a hard time, is it going over or under set temp? if you can pinpoint the leak in the reservoir you could shove some epoxy orJB Weld in there. if you can’t pinpoint it either send it in for servicing or get a new one (you may need to to solve your temp stability problems too–some of those just suck) good luck!
It’s not like regular teflon tape that you would use for pipe threads, it’s packing cord. Either way it doesn’t seem to be working. Do you have any suggestions for packing rings?
We were thinking JB weld for the leak as well if we’re able to find it. As for the temperature settings, it’ll undershoot if the cool is on and overshoot if the heat is on. It does this when we set it to 40 degrees. You would think it would need to be on cool since it is fighting the hot vapor from the evaporator but it just cools and cools.
I may help you find the seal for the 3 gear pumps if provide the model number of the gear pumps. Or you can DM at any time. That issue will happen frequently.
could you measure the diameter of the shaft with some calipers?
to me that looks very similar to the gear pumps on a VTA VKL-50 or 70, i’m trying to find an example of the shaft seals.
i think these seals, being tailor-made for that purpose, would fit perfectly around the shaft and fill out the space under the flange perfectly too, so would make a more perfect and durable seal than mashing flexible material into the space. and they’re more rigid in comparison to the rope you’re using so would would hold up for longer
example of the rings i’m talking about, you’d want to make sure theyre the right diameter of course. we use these in our gear pumps in our VTAs and they last awhiiiile–don’t need to replace for months in our experience. https://www.ebay.com/itm/124190600216?chn=ps&mkevt=1&mkcid=28
these are the exact ones we use, again from the photos your pump looks almost exactly the same. having a hard time finding these specific ones anywhere online except for the ordering portal on www.app.RootSciences.com
Yup, so does mine. So that’s what the screw on the side does. You can hook up an oil source. Interesting. Does yours have a reservoir? I love to see a photo!
one would want to make sure the seams on these rings are on opposing sides when packing on top of each other. the arrangement here lines up that ‘Block-Up Ring’ with the port for the oil input, so which each rotation it will allow a little sip of oil in (if it’s needed). @voltabiotech do you have a threaded port for this oil tube? if you do, and you’re not using it as an oil input, i’d recommend blocking it up with a female compression cap to prevent vac compromise from that spot
Hi there! We desperately need help getting our gear pumps working properly!!
We have three gear pumps that we are using on our wiped-film distillation unit.
One controls the feed of the sample, the other two control the discharge of the material through the outlet valves.
We have had endless vacuum leak issues with all three of these pumps. We have tried repacking all of the motor stuffing boxes with 3/16" teflon packing material, and also tried EPTFE/graphite fiber (w/silicone lubrication) without any luck. We also have been lubricating the packing material with vacuum grease too. It will hold vacuum for some time, and then after the distillation unit cools (overnight while we’re closed for example), then heats up again, the vacuum leaks return.
We have also had an issue with the bolts leaking vacuum on these pumps. We tighten and tighten and then end up destroying the packing material. Can anyone recommend a different type of packing material? Should we use a different type of seal instead of packing material? Like mechanical seal? Any advice on what to try next. We’ve been at this for weeks, LITERALLY WEEKS. Helllpppp!!
