2- Stage 50L/m Oil Free Lab Vacuum Pump Oilless Medical Mute Pump HZW-165 (110V)

I wanted an oil free pump for getting water out of damaged surfboards. Don't need super high vacuum and didn't want to deal with oil changes. This pump does the job, it's quiet, and it pulls a vacuum exactly to the listed specs. I had some trouble changing the supplied inlet fitting to a different fitting that I purchased. The metal was pretty soft and I was not able to remove it without damaging both the fitting and the inlet filter. I contacted the seller and they promptly sent me a replacement filter/gauge with the inlet fitting already removed so I'm good to go now. I was really surprised to get such solid customer service for an item like this. Really nothing to complain about.

I want to preface this by saying that I was a complete amateur when I bought this with respect to lab equipment. Not much has changed since then, but at least I know the basics of what NOT to do, which would already be common knowledge to someone who has taken a chemistry class in the last 25 years!This thing is an absolute workhorse and it just keeps on running.With this pump I have:- Overflowed my vacuum flask filtering copper nitrate (multiple times) which completely flooded the inlet filter and had copper nitrate spraying out of the exhaust- Pumped so much nitrogen dioxide through that it condensed back to nitric acid in the inlet filter and completely dissolved the brass screen and 75% of the fitting- Pulled a vacuum through my hydronic heating system to remove air bubbles, but wasn't paying attention and pulled at least a gallon of water through the exhaust- Left the pump unused for 3 months with all of the chemicals in it where the piston seized. I took the case off of it, manually turned the fan a couple of revolutions, put it back together, plugged it in and it started right back up!As far as maintenance, I have only replaced the inline filter because all of the metal deteriorated to the point that the brass fitting sheared off when I put the slightest torque on it with a wrench. As a testament to the abuse that it has suffered since I replaced the filter, the spring on the drain of the new inline filter has completely dissolved in acid/acidic gas, so I have a 16oz hammer claw hanging on the drain to keep it closed!As I said, this pump is an absolute savage and can take all of the abuse (intentional or accidental) that you throw at i. It's an incredible value for the price.10/10 I WILL buy again IF this pump ever bites the dust.1/6/23 UPDATE: I have been trying my hardest to kill this thing, and it won't die! I've been using it since my last review on in January 2022 without a trap because I never had [made] the time to replace the one I dissolved with nitric acid. The pump sat for another several months unused, likely with acid gasses condensed in it from my various abuses since purchasing it, I switched it on, and it was seized again. I opened it up, used some TriFlow lubricant, put it back together and it LIVES!9/9/23 UPDATE: I let it sit again for another 6 months to find it fully seized. Took the top of the cylinders off with an Allen wrench, saw the pistons were completely caked in chemicals. Pushed down on one which released the piston housing and wiped it off. Pushed down on the other one and pulled off the cylinder housing and wiped it down. Smeared some red grease on the inside of the housing and on the piston seal. Put it back together and turned it on and to my surprise it pulled a vacuum! This thing WILL. NOT. DIE. I don’t think I have ever abused a piece of equipment as badly as I have this one and had it keep running. Still 10/10 would buy again.

Ive used this thing for a year now and its a workhorse. I use this for gold refining. Ive accidentally sucked up nitric acid, HCl, you name it, it sat up for months and still works like a charm. I changed the outgoing barb (1/4" NPT) to a larger one to match my vacuum flask https://a.co/d/3JUs7nw , which uses an 5/16" / 8mm hose. Also added another regulator from HD so it wouldn't be quite as strong and blow out filters in the buchner funnel. About to buy a spare in case they stop making them, just because its that good.

Not enough vacuum for stabilizing wood, inlet fitting very soft brass (broke it off trying to change to what I needed) now can't return. Dust collector.

I like this little pump. Even if it gets waterlogged, just dump the water out and it keeps on going. Check intake tubing to be sure it's not clogged, You should feel lots of air blowing out the exhaust when there are no tubing clogs. I use a pressure cut off switch and can walk away confident the system maintains vacuum (I go 5 mm, that's all I need.)

It was very quiet and it was able to pull a vacuum to -25 PSI so it can close but what I read in the manual you have to replace the piston rings every 8,000 hours and I would just rather go ahead and get the oil pump instead of having a tear down the whole thing to replace piston rings but all I know it was light easy to carry around and help early decent vacuum and I would like to know if it is made for circulating water because it has an intake and outtake and show's 50lph

This vacuum pump works great for vacuum filtration, but the hose it comes with is the wrong size. Removing the brass hose connect and replacing it was difficult because it got crushed by my wrench and destroyed.

I use this little powerhouse as part of a vacuum clamping system in my woodshop and it is amazing. Super quiet and strong! Was a little skeptical at first, but it has performed like a champ!