SuperOxide
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Broke the plastic in/out port of my KNF N811 vacuum pump.
One step forward, two steps back...
I had this thread open a bit ago where I was taking some advice on replacing the busted valve and other plumbing, which I got working and had an
excellent result with it pulling a very good vacuum. But then I went to replace the parts with some other replacements I got off of Amazon, and got a
little overzealous with the tightening and cracked the plastic piece at the top that you screw the nipples into. You can see on the picture below that
I tried to epoxy it, and while it kinda works, the vacuum it holds is quite a bit less (use to be -25 inHg, now it's more like -17 inHg), and before I
also use to be able to turn the pump off and it would hold a vacuum for at least a little bit, now it looses it immediately.
I looked on the product page but didn't see any product schema documentation, and im honestly not even sure what the part is called. But I do see it on some other
pumps on ebay, so it has me thinking that maybe its a somewhat common part that I just don't know the name of?
Does anyone know where I could buy a replacement? Thanks.
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SWIM
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Have you tried contacting them via the Email on the page, or requesting a catalogue? Their catalogue might include spare parts.
I've seen posts by others about rebuilding KNF pumps. They were those blue KNF Neuberger PTFE pumps, which I think are identical the Chemglass PTFE
lab pumps.
If they have parts available for those they probably have them for your model too.
Your location, Devil's Anus, is unfamiliar to me; but it sounds like it must be a part of the USA(maybe AZ?).
If it is you can even call them toll free at 1-800-MASTERFLEX
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SuperOxide
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Quote: Originally posted by SWIM  | Have you tried contacting them via the Email on the page, or requesting a catalogue? Their catalogue might include spare parts.
I've seen posts by others about rebuilding KNF pumps. They were those blue KNF Neuberger PTFE pumps, which I think are identical the Chemglass PTFE
lab pumps.
If they have parts available for those they probably have them for your model too. |
I actually just did, I
got a reply saying they had a spare parts kit and gave me a link: https://knf.com/en/us/solutions/laboratory-equipment/details...
But the Spare Parts Kit doesn't exactly give any details on what parts are included.
| Quote: Originally posted by SWIM | Your location, Devil's Anus, is unfamiliar to me; but it sounds like it must be a part of the USA(maybe AZ?).
If it is you can even call them toll free at 1-800-MASTERFLEX |
Yep, AZ, lol.
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SuperOxide
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Bad news: I got a quote for the parts I wanted, way too expensive... I would have to buy the spare parts kit which is $285.60.
Good news: I got another pump that's basically the same, for less than half of that price, and I can use it for parts.
Still sucks that parts from the manufacturer are so damn expensive. I would have two perfectly working pumps if I could afford that kit >_<
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monolithic
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Is the part as simple as it looks? You could probably pay a machinist half of that to machine a brand new one.
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SuperOxide
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Unfortunately, it's not as simple as it looks on the outside..
Other pics of it here: https://imgur.com/a/eDJ1MSh
I'm sure the waffle cone pattern could be left out, but I'm not confident the inlet/outlet could be done with a tight enough tolerance as needed (or
as I assume is needed).
Oh well, looks like this one will be used as parts for now, lol.
Note: Technically it does still work with the epoxy, it just seems to pull ~5 less inHg than the other one I got. So I could use it if needed.
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Rainwater
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3d print. Haaaaaaa.
Nasty hack.
No.
K
So fully reassemble your apparatus
get your air compressor and apply 1~2 psi to a medium size balloon(hydrogen works best but heliumwill work to). Make about two or three.
Then attach the air compressor to your vacuum inlet.
Mix part with 1 part dawn dish soap and 50 parts water. With pressure applied to the unit. Spray/ paint the soap/water solution and look for bubbles.
Sand down anywhere their are bubbles poping up
Paint with liquid superglue or any epoxy you have on hand.
Remove the pressure. Disassemble and hold your finger over the inlet. Apply air pressure and soap it down again. Find the bubbles and patch
Be very careful on the interior and stay away from the flat areas that make connections to the interior of your pump.
Check any gaskets you see. A drop of mineral oil will help seal them
Quick google search found this.
That looks like the "head plate"
https://www.google.com/url?sa=t&source=web&rct=j&...
"You can't do that" - challenge accepted
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SuperOxide
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| Quote: Originally posted by Rainwater | 3d print. Haaaaaaa.
Nasty hack.
No.
K
So fully reassemble your apparatus
get your air compressor and apply 1~2 psi to a medium size balloon(hydrogen works best but heliumwill work to). Make about two or three.
Then attach the air compressor to your vacuum inlet.
Mix part with 1 part dawn dish soap and 50 parts water. With pressure applied to the unit. Spray/ paint the soap/water solution and look for bubbles.
Sand down anywhere their are bubbles poping up
Paint with liquid superglue or any epoxy you have on hand.
Remove the pressure. Disassemble and hold your finger over the inlet. Apply air pressure and soap it down again. Find the bubbles and patch
Be very careful on the interior and stay away from the flat areas that make connections to the interior of your pump.
Check any gaskets you see. A drop of mineral oil will help seal them
Quick google search found this.
That looks like the "head plate"
https://www.google.com/url?sa=t&source=web&rct=j&... |
Good point. I actually have used that technique to find leaks, but my stupid brain thought "I don't think I can use that when its pulling a vacuum",
should have thought to just blow air in it, lol.
thanks!
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Rainwater
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Did you get it fixed?
"You can't do that" - challenge accepted
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SuperOxide
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I bought another pump of basically the same model with the intention of using it for parts, but it worked better than my other one did (despite being
cheaper), so I now am switching the two, and using the one pictured in the original thread for parts (or technically it still does work, just not as
well).
On a side note, I was taking a picture of the gauge at max vacuum, and I noticed that the frame rate of the camera and the vibration of the needle
made it look like the needle is made of rubber, lol.
https://imgur.com/a/gmg9WRU (It's a video, can't embed it)
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