AngryOnion Posted July 26, 2022 Share Posted July 26, 2022 Hey guys, what are your opinions about buying good sized (50+ gallon) used air compressors? I'm worried about the hazard of not knowing how well they were taken care of. Is there an age cutoff you do or what else do you look out for? I know they can last for decades but I'd rather be safe than sorry. Link to comment Share on other sites More sharing options...
Daswulf Posted July 26, 2022 Share Posted July 26, 2022 Some considerations are: 1, if the tank is rusted inside or outside for that matter. The danger with some tanks could be the rust on the inside from not draining it regularly. You might have to run a video scope to check that out. If the compressor is hooked up and can run when you check it out vent the drain to see if rusty water comes out. 2, what condition is the pump in. Has it been maintained? Is the oil clean? Are the pump rings and valves good? A worn out compressor may take a long time to pump up to full and run a lot more to maintain the pressure. Smaller compressors may be oil less and have a teflon ring on the piston to pump air. The rings and sleeves wear over time and may need replaced. Generally larger compressors do not have this. A side note, oilless compressors are generally much louder. 3, look up availability on parts on the compressor you are looking into. Some brands have good availability while others might be obsolete. 4, check the air filters. Again good to look at part availability to be able to replace those. It is best to be able to check out a running compressor. If looking at one that has been sitting you have some unknowns as far as it functioning. Does it hold/maintain pressure? Does the pressure switch work? Does the safety pop off valve work? How much air will you need? What will it be running? Those are considerations as well. Getting an underpowered compressor will put more strain on it and reduce your workload. This is where it is better to go a little bigger than you really need. Not crazy big but bigger. I will admit to not knowing much of anything about screw type compressors. I'm sure there is more but those are some of my thoughts at the moment. Link to comment Share on other sites More sharing options...
JHCC Posted July 26, 2022 Share Posted July 26, 2022 Das has a lot more technical knowledge than I do about this, but I do have one thing to add: What do you know of its former use? If it's coming out of a barn covered in muck and dust and doesn't look like it's been used in decades, that's one thing. If it's coming from a shop where it's clearly been well-maintained and is only being sold because they're upgrading to something larger, that's a different thing entirely. (Just remember to take the seller's assertions with a grain of salt, unless you already know and trust them.) Link to comment Share on other sites More sharing options...
Latticino Posted July 26, 2022 Share Posted July 26, 2022 Other considerations are the compressor itself. Das mentioned oil or "oil-free" types. There are also single stage or two stage compressors (look for number of cylinders). Typically the latter provide more compressed air at higher cfm. It is important to realize that compressors are rated for pressure at a specific airflow (i.e. 11 CFM at 90 psi). This becomes critical if you are running equipment with significant demand for compressed air (like a sandblaster or power hammer). Needless to say your motor selection should match your available power and environmental situation (TEFC for locations with a lot of metallic dust for example). Link to comment Share on other sites More sharing options...
Frosty Posted July 26, 2022 Share Posted July 26, 2022 I don't have anything to add to the above. Maybe if our Twisted Willow gets a break from work and checks in he'll have input. He fixes things including compressors. IIRC. A repairman's perspective is good to get when looking at used equipment. Eh? Frosty The Lucky. Link to comment Share on other sites More sharing options...
swedefiddle Posted July 27, 2022 Share Posted July 27, 2022 Good Morning, I have one compressor wired in and hooked to another air tank. One tank under the compressor, one or two other tanks in the Air loop as reservoirs. The reservoir(s) keeps the system pressure a lot more even. When running a Glass Bead cabinet, it allows you to work longer at a higher pressure. Air tanks can go up, off the shop floor, or under stairs, out of the way. Just make it easy to drain the tanks. Neil Link to comment Share on other sites More sharing options...
AngryOnion Posted July 27, 2022 Author Share Posted July 27, 2022 So this just happened after I made this topic. My small 3 gallon air compressor started leaking. I put soapy water and it is leaking between the two brass pieces. Is there a gasket that needs replaced? It is a Craftsman 3 gallon direct drive. I'm busy most of today but might be able to take it apart tonight. Link to comment Share on other sites More sharing options...
Daswulf Posted July 27, 2022 Share Posted July 27, 2022 Being a craftsman, you should be able to look up the model number that should be on it and get a schematic online. That would tell you if there is a gasket there and possibly even be able to order a new one. Link to comment Share on other sites More sharing options...
AngryOnion Posted July 28, 2022 Author Share Posted July 28, 2022 Got time today to check it out, gasket went bad. Link to comment Share on other sites More sharing options...
Frosty Posted July 28, 2022 Share Posted July 28, 2022 I concur. Frosty The Lucky. Link to comment Share on other sites More sharing options...
AngryOnion Posted July 29, 2022 Author Share Posted July 29, 2022 Replaced both gaskets for cylinder head and good as new now. Link to comment Share on other sites More sharing options...
Frosty Posted July 30, 2022 Share Posted July 30, 2022 Don't you love it when a fix is easy? Frosty The Lucky. Link to comment Share on other sites More sharing options...
Daswulf Posted July 30, 2022 Share Posted July 30, 2022 Glad to hear. Compressors can be easy cheap fixes or the fix can be more than the compressor is worth. I've picked up a few smaller ones for free that were in good outwardly physical condition but it just isn't worth fixing them, so I saved them for parts or to use in scrap art. Link to comment Share on other sites More sharing options...
Irondragon Forge ClayWorks Posted July 31, 2022 Share Posted July 31, 2022 TWISTEDWILLOW (Billy) makes nice small coal forges out of the pancake tanks of the small compressors. Link to comment Share on other sites More sharing options...
eseemann Posted December 31, 2022 Share Posted December 31, 2022 This is why I think twice about used compressors Link to comment Share on other sites More sharing options...
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