Robinair (15500) VacuMaster Economy Vacuum Pump - 2-Stage, 5 CFM , Red

I had limited budget for my project and ordered used pump and gauge. First pump arrived damaged. The first gauge was in rough shape. I ordered replacements. I tested them with a brand-new gauge set. The pump is rated at 35 micron and I didn’t have high hopes but I was surprised. It held 24 micron for 2 hours before I stopped the pump. I don’t work on AC units everyday and it’s more than enough for what I need it for.

I committed the typical amateurish error of trying out cheaper two-stage vacuum pumps...with predictable results. They either didn't perform as advertised right out of the box, or they failed within several uses - even with proper maintenance.This thing, however, delivers on the promise.I filled it with the included oil. First time powering it up, it pulled the rated vacuum quickly when dead-headed.That first charge of oil became cloudy after just a few uses, so I drained it and replaced it with fresh Robinair vacuum oil. At that point, the ultimate vacuum plunged to 9 microns. (I suspect that the first charge of oil took the brunt of the break-in, and that's why it clouded up so quickly. But that's something to be aware of if you buy this pump. Keep a close eye on the clarity of the first oil charge, as it will probably cloud up pretty quickly.)Since then, this pump has been worked very hard. It has been operated for hours on end with no loss of performance whatsoever. Since my application doesn't expose the oil to excessive moisture, the oil has remained clear after the equivalent of days of operation.There is oil fog released when the pump is operated under no load, or when it is under load but evacuating at a high flow rate. It's inevitable and is present with all pumps of this type.There are aftermarket oil mist separators available that can mitigate the oil mist, but they're expensive. Just expect the oil mist, and make sure you have adequate ventilation wherever the pump is operating.

Arrived fast. Works Great.

Pump came damaged from poor packaging. The guard that covers the cooling fan was dented in and touching the fan. Very easy to fix and pump worked very well after. Comes with the three main sizes of inlet fittings. It includes a large bottle of vacuum oil. There is a little more than you need to do the first fill for the pump. Does not have enough to do the first change after break in. Pump is made of well made cast aluminum for the case and steel internals.

I have read some of the reviews of how the pump is used and the oil turns black or spit out oil i can say i did experience the oil turning a little dark but ive bought the pump with new Robinair Oil and followed the instructions, ive also let it ran 10 more minuets after the initial brake in period just to make sure everything worked well. ive changed the oil after and let it ran again to see if it was just old oil that came with the pump or if the pump was actually burning or was defective. i am happy to say that it was just the oil that came in the box. ive used it for 2 hours on a job and checked back and the oil is still some what clear but is understandable seeing how the AC system had a lot of moisture so the oil would look a little cloudy, changed it and started on another job and again no problems had a strong vac micron levels were where it should be. the oil that "leaded out" was dude to a very slight over fill of oil after ive adjusted the level no issues at all. my advice is to fill the pump up to the point were the edge of the oil surface tension reaches the sight glass line doing so in my case seems to fix the spitting oil out the exhaust filter, if you cant get it just right i dont see any reason to make a small extension to compensate the oil spitting out the exhaust filter, over all if your a DIY or dont know how to use a vacuum pump or service it ask some one for help because this pump works very well for small to mid side jobs. the only thing i want this pump to have was a larger oil capacity for a longer run time so i dont have to stop it and change the oil as often dude to the high humidity area where i had used this pump in. for the price you pay for it your getting a pretty good deal, most likely buy the 8 cfm in the near future just to save some time hope this helps someone.

I wanted to install a mini split and all local HVAC companies wanted thousands of dollars. I was able to buy one on Amazon and with the help of this vac pump, suck it down way below 500 microns and get it up and running!

There is nothing to hate about this pump! After reviewing multiple different pumps, I settled on this one knowing that I wanted a 2-stage pump. This held a vacuum for well over 90 minutes and is super quiet. The pump never got too hot to the touch and just simply worked. This was used to vacuum 3 line sets totaling just under 125 feet.For those wanting to install a mini-split yourself - this pump is a perfect addition to the Yellow Jacket R410A manifold setup, 3/8" MegaFlow Vacuum Hose, and both the Appion MGAVCT (1/4") and MGAVCR (5/16") valve core removal tools.If you decide to do this yourself - rent, lease, or buy a nitrogen bottle from your local AirGas or equivalent so you can purge the lines, run a pressure test, then pull a vacuum. Pulling a vacuum alone is not enough to ensure your lines are leak-free.I am not an HVAC tech - just a motivated home-owner - that was motivated to finish this myself after getting a quote of over $7K to pressure test and vacuum the work I already completed, and install a concealed-duct unit in the attic. I saved myself about $6K! Sure, manufacturers want you to have a licensed HVAC tech to do the work (or release the refrigerant) for warranty purposes - however, when properly tested and vacuumed prior to releasing the refrigerant, these units will last as long as the typical central AC systems.