sounds like you need to clean it more aggressively.
Your pump may not have been abused the way most are, but if you’ve got problems with “fresh” oil looking fouled, then it’s time to throw something like this at it.
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I appreciate the info but my pump will get to 150-170 F and putting kerosene in it seems like it could be dangerous? Any idea what the flash point of kerosene is?
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Flash point seems to vary depending on what mixture of hydrocarbons you’re calling kero today.
Try the other suggestion from that thread?
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My pump is so hot during flushes I need gloves to tip it. The directions are 50/50 pump oil to kerosene which drastically changes the flash point I’d imagine.
I have to say mine gets well into the range and that worked perfect for me
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You could try a “power flush”. It can be a little messy but very effective. Drain the pump. Prepare a couple of cups of fresh pump oil. With the drain port unplugged, pour the oil in the vacuum port just as you turn the pump on. Place a collection vessel angled to receive oil as it shoots out.
If I don’t say it, someone will leave the pump running. BUT, turn the pump OFF just as you finish pouring the oil into the vacuum port.
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Has anyone tried this on a rotary vane yet?
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Why would you use kerosene? Ive always been told warm ethanol is all you should use so as not to tear apart the vanes. Its a pretty delicate situation in there. And getting a pump to bounce back from a solvent flush can already take a long time. Kerosene has a boiling point between 150-275C so it isnt going anywhere, it also will mix extremely well with your pump oil so it wont be easy to fully scrub.
The way ive had success it to simply empty the pump of all oil, fill with warm to hot ethanol. Allow to soak for an hour. Turn the pump on and off quickly with the inlet locked off… repeat this a few times… drain and refill with oil, run, check vac. Dump… run check vac… and if the vac isnt back to at least normal, just open the ballast and run for an hour. The pump should get hot and expell the residual ethanol.
Ive seen a pump recently where someone tried the kerosene trick… it was spewing what looked like vane sludge and smelled of lacqeur thinner… it also sounded terrible. I didnt know thats what they had done… i simply turned on the pump… heard it… shut if off and said thats not right, is something wrong with this pump… we dumped the oil… and man i reeked… and was black polymer looking oil… refilled… ran, drained… same thing… the pump was just falling apart… there could be more to the story of that pump that i dont know… but why use a high boiling solvent in a percision system based on the vapor pressure of the oil. When you can safely use a low boiling solvent and it works everytime…
also… the amount of times ive actually had to do this is 2…
Once was on my own pump Just to try it after provac mentioned it… vac depth was already 3 micron… after it was 2 and what came out was astonishing… and it worked without concern…
The other was to save a welch someone had seized up via a muffin that ended up in the pump. I poured hot iso all down every hole… turned it over by hand until
It started to smooth out… drained… refilled… same thing… over and over until i could turn it on with the iso and it would run for a second without and catches… then we let it hot soak over night… then oil… oil. Oill… and done… good as new… below 5 micron…
No offense @Soxhlet i trust your judgement… but im just lost as to the reasoning…
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What is the boiling point of the pump oil?
Closer to EtOH or kerosene?
What do you imagine the kerosene could possibly dissolve in there that you don’t want it to?
How about the relative lubricity of ethanol vs kerosene?
If adding kerosene causes all sorts of black goo to run out, and ethanol does not, which is doing a better job of cleaning?
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I use kerosene for a few different reasons.
First it mixes with the pump oil, the etoh will not.
Because it the oil mixes with the kerosene, it provides lubricity to the pump while cleaning.
Kerosene will dissolve more of the contamination and baked in grime. Another advantage that kerosene has is it is easy to source.
Running your pump for several hours is reccomended to drive off the remaining solvent after flushing with fresh oil. While 50% kerosene and 50% oil works, there are other alternatives out there such as flushing oil. always check your pump to make sure it can handle the solvent. Some pumps have plastic sightglasses. Flushing Fluid for Vacuum Pump Cleaning and Maintenance
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Why waste effort cold trapping for trash volatiles and cleaning your pumps, when a gas bubbler filled with pump oil will usually solve most of your contamination. Especially when paired with a molseive trap. Your vane and sealing materials construction will determine what is good for cleaning. Most vanes are bronze, cast iron, or phenolic plastic. If you have your wits about you and you wanna solvent wash a pump, choose solvent appropriately. One drawback of straight solvent wash is removing lube from the pump shaft welcoming shaft fretting and lip seal/oring damage. If you have a belt driven pump (Welch) use a mechanical seal when the leaky lip seals groove the shaft. Overhaul kits are cheap, rebuilds are simple, and pumps are expensive. If you have a direct drive pump, see if you can move the motor fan by hand or pull it’s cover to prime. Have the oil reservoir sections of your pumps ptfe coated. Rebuild with viton, find your local hydraulics shop and you’ll have a great source of elastomers. Make sure you use the right type and viscosity oil for your pump and make sure to keep it cool (fan) as it runs to twart thermal expansion and oil breakdown. Build a pump to suit your needs and issues are maintenance based. If it is easier to modify your system, do that. As this industry tightens up more process control equipment and procedure will become common and these issues will be like “purging temps” and “rubber smell”.
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The only issue I see with the molseive traps are the method of regeneration. At the end of the day the pump still needs to eat the volitiles that were trapped in the seive during the regeneration process. It seems that running with the ballast open would have the same effect no?
edit:This could be fixed with fresh seives each time, and regenerated outside the filter. But wheres the fun in that?
Beware of faulty vac gauges when using your pump. Mine, unbeknownst to me, started “failing” giving incorrect readings within 3 months of use, leading me to think my pump was on the fritz. After 5 gal of oil being wasted and talking to various people about it I was informed that gauges need calibrating after one years use. So I got an Edwards gauge recently so I could send the other one to be calibrated. Lo and behold, the pump I thought was the issue now pulls to 1.2 micron blanked off. I was mighty surprised. The previous gauge never read below 15 even when I first got it…
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Been reading all the posts about vacuum pumps…some correct…some way off. I have been using pumps of all different kinds for many years on units that canna people couldn’t imagine…units that run less than 1 kg per hour up to units that run 400 kg per hours. With that said, the canna industry is starting to move up to equipment running much larger volumes. Vacuum pumps are the heart and soul of the units and also most misunderstood…everyone has there opinion. My preference is the Leybold brand pumps…most robust units and have given me the best performance…I run some wild crap at times. I have my guys change the oil every night and we extend the required maintaince out pretty far…they do require rebuilds at times believe it or not. Edwards pumps used to be good when they were made in England…when they switched pump manufacturing to India…quality when to crap…with the exception of the scroll pump series. Now the guy using a rotary vane to distill EtOH…why? Use a diaphragm pump…KNF makes a great pump…just lead times are long. Plumb the heads in parallel for higher cfm and in series for higher ultimate vacuum levels…usually 25 to 40 torr. More than enough for a EtOH distillation. In closing if you change the oil often and use the correct vacuum level for the operation you can extend the online time…pulling too strong of a vacuum allows the vapors to bypass the condensers and cold traps…which kills the pump. I recommend you always have a backup pump on hand and a rebuild kit if you are mechanically inclined.
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The br cold traps get a ton of terpenes in them and they just sit there until the system is cleaned. So you might not be running it as “empty” as you think. If you take the cold trap off the back and squirt a solvent in there it will probably come out the other side red. Cleaning the pump is only half the job unfortunately.
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I like the parallel and series options you explained any pics would be helpful for future members
Knf lead times are long but there are loads for sale used in often good conditions
Nice write up 
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Thanks for the kind words…wish I had pics to share, but I will try to explain…it is not that hard. Now I am obviously talking about dual diaphragm head pumps…single head pumps…well there is no explanation there. On the pump heads, there are flow direction arrows that show you how the gases go through the pump…an inlet and an exhaust. In high vacuum mode the heads are plumbed in series…the exhaust from the first head is plumbed to the inlet of the second head…you have one inlet connection and one exhaust…flow arrows going with the flow. The first head does most of the work and the second head takes the pressure down the rest of the way. So you get the maximum vacuum, but you sacrifice CFM’s. In parallel, both inlets are connected together and both exhausts are connected together…flow arrows both going in the same directions…inlet to exhaust. this configuration gets you max CFM’s…sacrificing ultimate vacuum. In order to change the flow direction of the head, just remove the bolts holding down the heads and spin them 180° until the flow arrow is pointed in the correct direction. I hope that helps.
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Yeah, I just connected mine in parallel. Second pass 8.2 micron lowest. Notable increase on flow at 200c outside flask. 160 vapor temp. Need to do some water washing to remove red pigments, but looks golden under light.
Edit: beware of changing temps though, drastically changes color within a few degrees.
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I’m gonna double recommend running the gas ballast. I’m doing it on my two pumps from yesterday’s run. The second pump went to 1 micron then started giving me “ur” reading followed by a bunch of weirdness and I saw a small x10 symbol at the bottom of the gauge. Confused I looked at my trusted pressure conversation chart and lo and behold. It means submicron. So no kerosene, just the flushing fluid when I got the pump and running ballast means I’m reaching 0.4 as lowest now. Again this was with a pump a professional tech said pulled 2.4 micron as its ultimate vac.
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