TOPIC:

 Finally bought myself a small blast cabinet. Of course the portable compressor that I use for work (6liter) is way too small. I borrowed a friends (20liter) and that's also too small.
The specs on the cabinet say it takes 260 liter/minute @ 6 bar. Looking at new compressors,the max my budget will stretch gets me a 50liter that puts out 235 liter/minute gross and 165 liters/minute net at a max of 8 bar.
 To be honest,I'm a bit lost here. whats do the net/gross specs mean? Will this compressor be any good or will it be way under powered? I'm not planning on heavy,all day use, I just want to be able to blast some small parts now and again.
 Any help and advise would be well appreciated.Thanks in advance.

Sounds as though it should be OK. You'll need a good condensation trap on it. You can always stop for 5 mins whilst the tank recharges but theres nothing as infuriating as stopping to clean clogged media every 5 mins.  
 

Ok so the cabinet consumes 260l/m at 6bar during continuous use.
You usually are not up to nick to run your blasting cabinet continuous any way, at least if you are a hobbyist. 
And one needs to have a very roomy budget if one wants to buy a screw compressor with a reasonable tank and preferably an air dryer that outputs an ocean of air.

so if you go for a compressor with a 50l tank and puts out 235l/m at 6bar, means that you will have to take a break when you exhaust the air supply and will have to e to rearrange the stuff in the cabinet. 

One idea can also be to look for a nozzle that require less air when you settle in. Cuz the compressor I bought when we opened the vapour blasting business was deadly expensive which is usually not an option for the hobbyist.

/A

 

Never worked in litres per minute but CFM .
Minimum you want is 14cfm at around 90psi.
6 bar is around 87 psi so close enough and 260 litr works out around 10cfm which is on the low side.
It's swings and roundabouts on the receiver size as for a given compressor output as a small one fills quicker but you get short blasting time between fills.
A large one takes longer to fill and will give a longer blasting time.
My small compressor is 14cfm and when used for blasting never gets a rest.

 

Sorry no picture because it's in my storage shed right now, but this is the blaster I used. www.amazon.com/OEMTOOLS-24815-Bench-Abra...r%2Caps%2C383&sr=8-3. Mine is Red though.

And this is the compressor spec on mine. It is on small side but it does the job. I have used from 120 grits Glass bead to 60 grit Aluminum Oxide to blast both steel and Aluminum parts. Maybe because my compressor is not big or strong enough to do any damage using Aluminum Oxide but it does clean pretty good.

As everyone has said, make sure you have good air/water separator and make sure it's about 25 feet from your compressor. Don't make the same mistake everyone makes and install the separator directly or too close to the compressor. Air/water need time to condensate back and if it's too close, air is too hot and it won't separate. If you don't have enough space, just run the 25 feet hose all coiled up and just install the separator at the end of the hose, and run another hose for the tools/blaster cabinet. this is the setup I use. I run two 25 feet hose with separator in the middle. make sure the separator is at upright position. You will not believe how much will condensate first time you use. And make sure you check the separator often, specially on hot muggy day.

I have run the cabinet without the separator and it still work. It just you need to stop every 5 minutes or so, unscrew the nozzle from the gun and clean the nozzle. Sand will accumulate there due to moisture and you WILL notice of the blaster not peeling/cleaning anything. BTW, my compressor is Old Craftman (almost 30-years old) with 25 Gal.

For a good many years I survived on a 20 gallon 2 hp Campbell Hausfeld compressor that put out 5.5 CFM @ 90 psi.  Way less than most people would recommend, but I restored two complete bikes, including doing the frame, with that unit.  

What voltage and amperage are available for the compressor? 

Standard European system.230 volt. Not sure about amps.

Thanks for all the replies. To be honest,I'm still no further on to sorting this thing. I've been making some calculations and conversions and this is where I am at the minute.
 The cabinet needs 9.18 cfm @ 87.02 psi. The 20Liter compressor I borrowed puts out 1.94 cfm (net) or 2.82 cfm (gross) - I have no idea what this net/gross means and which I should use-.I get,maybe 5 seconds,max,of blasting before the compressor kicks in again and I have to wait nearly a minute for it to refill.
The affordable 50Liter compressor I'm considering puts out 6.18 cfm (net) or 8.82 cfm (gross) @ 87.02 psi.
So, the 50 liter puts out around 3 times what the 20 liter one does (but it still doesn't go above the 9.18 cfm  thats wanted for the cabinet!)  Can I figure that if it puts out 3 times more cfm, it will give me 3 times the 5 seconds blasting time???
 Is that the best I can expect or am I completely misunderstanding how this works?

Depending on the media you use and the job in hand you shouldn't need to run it at full pressure all the time which will prolong the working period of the tank. Also pulsing the gun prolongs tank capacity.
Bottom line is unless you plan on doing a lot of blasting buy the best comp you can and you make it work out. 
Pro setups are expensive because of the volume of work put through them. 
​​​

CMF requirement are very subjective and depend on duty cycle. If you blast a lot, you need a compressor that keeps up with air draw. However, if the blaster is seldom used, a smaller compressor can be used, Just get a big tank or parallel two tanks together and take breaks during refill cycles.

wrote:

Thanks for all the replies. To be honest,I'm still no further on to sorting this thing. I've been making some calculations and conversions and this is where I am at the minute.
 The cabinet needs 9.18 cfm @ 87.02 psi. The 20Liter compressor I borrowed puts out 1.94 cfm (net) or 2.82 cfm (gross) - I have no idea what this net/gross means and which I should use-.I get,maybe 5 seconds,max,of blasting before the compressor kicks in again and I have to wait nearly a minute for it to refill.
The affordable 50Liter compressor I'm considering puts out 6.18 cfm (net) or 8.82 cfm (gross) @ 87.02 psi.
So, the 50 liter puts out around 3 times what the 20 liter one does (but it still doesn't go above the 9.18 cfm  thats wanted for the cabinet!)  Can I figure that if it puts out 3 times more cfm, it will give me 3 times the 5 seconds blasting time???
 Is that the best I can expect or am I completely misunderstanding how this works?

The cabinet doesn't actually need that much air.  6 cfm will get it done.  What you do need though is a bigger tank.  50 L is too small.  Look for 75 or 100 L.  I would consider this the bare minimum.  Also, get an oil lubricated compressor with iron liner.  No oilless compressors.   When blasting, the compressor will be at 100 duty cycle, so you need something tough.