Compressor Info

[wcndave]

I am now thinking about getting a compressor, however am not familiar with them.

What is the relationship between litres, PSI and what tools it can run.

I am looking at a Bambi 24 litre 120 PSI, perhaps easiest if I could understand what this will NOT run?

 

[mailee]

Hi Dave, that size of compressor will run a nail gun but not much else. For spraying you really need something with a larger cylinder. I have managed for a few years with a 50 litre cyliner on a 3HP compressor but it was really only good for small projects. It owuld run out of steam trying to spray a wardrobe side. If you want ot power any air tools you will need at least a 150 litre cylinder and a pump with at least 12CFM output. If you are only using a nail gun then a small compressor as you describe will be fine. Oh and if you wanted to run a HVLP spray gun you will need a large compressor with a high output as these use a larger volume of air. HTH. :wink:

 

[wcndave]

Yer, i guess i should have stated that i have looked into spray systems, and would actually go for a Fuji HVLP system for spraying.

You introduced CFM which now adds to the specs of PSI / Capacity...

which one is the key number?

would the one i describe run air tools such as sanders, drills etc? the reason i was looking at tools is that they are much cheaper, and smaller when air powered, however if they don't work.... then i think I may give up on compressor and go back to electric nail gun, as my 50 sqm workshop not really big enough for a 125 litre compressor...

 

[woodpig]

I asked the same question years ago regarding running a small sand last cabinet and lots of folks said you had to have a large compressor. I wasn't convinced so found the smallest we had at work - probably 3/4 Hp 10 Litre and hooked it up to a cheap blast gun and it worked fine for what I wanted to do (you can't fit a car in a small blast cabinet!) :lol: I ended up buying a 2.5 Hp 25 litre and it works fine. Ask lots of folks what they run on their (size) compressors to get a better idea of what you need. Biggest issue for me is noise, I sure could do with something a bit quieter :?

 

[mailee]

No Dave, that one would definitely not run a sander or drill! For a sander you will need at least 13CFM and that is what is known as free air not pump capacity. A lot of retailers give the CFM of their machines but this figure is the pump output and not free air. As an example a compressor could be advertised as having a CFM of 10 but in actual fact the free air CFM will only be about 6 or 7. I have a large compressor with a 200 ltr cylinder and a free air CFM of 13. This runs my palm random orbit sander for about 7 mins before the pump kicks in to build the cylinder back up. Things like air nailers can run off a small compressor as the air they use is a quick blast. If you try to run air tools from a small compressor they will probably run slowly if at all and it will cause the compressor to be running constantly to try to keep up with the load. It will eventually kill the compressor. This is the reason I upgraded my compressor. I used to have a 3HP V twin compressor with a 50 ltr cylinder and a free air output of 7CFM and it just wouldn't handle air tools and would run out of puff trying to spray large pieces. It would however handle my large framing nailer with ease. I hope this is of help to you and I am sorry to give you negative views on it. :wink:

 

[wcndave]

Sounds like unless you go industrial, or pump up a lot of paddling pools, best to stick to electric ;-)

 

[Hudson Carpentry]

I run a 24L 8 Bar. With this I use brad nailer's, basic spray gun and even an impact wrench. The pump don't kick in when its empty but when its pressure goes below 6 bar. Its max is 8bar. I can spray a 3x6ft fence panel before the pump kicks and then about 2 more foots worth before the tanks below 4 bar and the gun stops spraying efficiency in as my spray gun works at 4 bar. My brad nailer works between 4 and 6 depending on size of nail and will fire between 20-50 brads before the pump kicks in and the impact wrench works at 6-8bar. The wrench will do 4 car wheel nuts before you have to wait a bit for it to fill back up. The required rating of the tools are normally on the side (and it there manuals) so a quick look at the tools you wish to use will give you an idea.

Now I get by quite fine with a 24l but at times do wish I had a 50l which ill be upgrading to soon. I want a 50L solely so when spraying it don't run out so quickly and if im taking a wheel off a car that has 5 nuts I don't have to wait a minute for the recharge to get the last nut off.

PSI and Bar are related and both are a measurement of pressure. Most low to medium range compressors will do around 115psi which is 8 bar.

The capacity is just how much air it will store. An 24l 8bar compressor will run just about any normal air tool like drills, sanders etc but not for long as the pressure lowers as your emptying the tank via using the tool. A 50l 8bar compressor will run the same air tools, just for longer.

When it comes to CFM I would only worry if your using professional sprayers (CFM is the measurement of how much air it will move in one go). If you are then a larger tank will be required other wise you will end up waiting for the tank to fill up which could cause your finish to be uneven.

 

[wcndave]

That is really helpful, sounds like it doesn't do quite enough to justify it in a small workshop unless I do a lot of nailing or need to blow away a lot of dust.

I think I was hoping to justify some new kit on basis of a nailer, however perhaps I am better putting it towards my kapex mitre saw...