Suitable air supply for Plasma Cutting

[GregEng]

I am looking into getting a small plasma cutter. I am thinking the small R-tech 30

I don't currently have a compressor, or have any other use for a compressor but supplying the plasma cutter.

The plasma cutter has a supply requirement of 3.5cfm.

I am very space limited at the moment, so the compressor I have been looking into is one where the framework is the tank. Hence the capacity of the tank is pretty small at 2.4litres, however the displacement of the compressor is 7.6cfm.

Would this be suitable for purely supplying the plasma cutter. I intend to be cutting sheet up to 3mm, no thicker. The cuts may well be quite long, 1 metre and upwards at times.

Here is the plasma cutter.

http://www.r-techwelding.co.uk/welding_equipment/Plasma_Cutter/Plasma_Cutter_R-Tech_P30C

and the compressor

http://www.machinemart.co.uk/shop/product/details/champ-air-compressor-230v-3

 

[Shox Dr]

7.6 is the displacement of the pump. The figure quoted by manufacturers is usually 25-30% less than. The Free Air Delivered CFM. So that's what you need to ask

 

[GregEng]

7.6 is the displacement of the pump. The figure quoted by manufacturers is usually 25-30% less than. The Free Air Delivered CFM. So that's what you need to ask

Sorry I a little confused by what you meant by 'free air delivered' is that the term which is used to describe the max constant output of the compressor?

If so what would be a suitable free air delivered cfm for supplying the plasma cutter?

So this style of compressor may be suitable for supplying a plasma cutter with tiny tank?

 

[Luke]

Based on experience, that compressor is far too small, in my opinion.

A friend has one of the pretty common 25L compressors, which probably has a similar sized pump to the one you linked to, but with a 25L tank. It runs the plasma for about 15 seconds before the plasma cuts out and the compressor has to recharge the tank.

Also, the compressor, hence the air, gets very hot, which usually means it's more moist than it should be, which lowers the quality of the cut.

 

[Shox Dr]

FAD is the MAX usable amount the compressor can constantly supply

 

[GregEng]

Would this be more suitable it states a free air delivery of 220litres.

http://www.screwfix.com/p/stanley-bostitch-scr007-10ltr-roll-cage-compressor-240v/27321

 

[Shox Dr]

220Ltr/min is 8CFM. If it's correct then yes

 

[steve.h]

I hhave a cut40, I bought myself a 2hp one on sale for 99 quid, plenty good, but be warned once you have a compressor you will find other things you want to do with it and it will fast become too small, if you can sped that sort of money get a 3hp job, or a second hand bigger one....

 

[StevieD]

I have just got a pre loved r tech c30, great little machine - I'm using my existing 3hp with a 200 litre tank, it doesn't take ong for the compressor to kick in if cutting a sheet of 1/8" steel from one side to the other. With a full resevoir the plasma will run for about a minute before the compressor starts up again.

I think you'll need a bigger compressor than the little one!

Steve

 

[86 slo-vo]

Deffinanly get more compressor then you will need, I have killed 2 small compressors trying to keep up with my thermal dynamics cutmaster 42 plasma.

The small ones can't keep up unless all your doing is a 6" cut.

I finally upgraded to a 90 gallon 5hp speed aire compressor that should keep up with anything I could throw at it.

 

[s410man]

Deffinanly get more compressor then you will need, I have killed 2 small compressors trying to keep up with my thermal dynamics cutmaster 42 plasma.

The small ones can't keep up unless all your doing is a 6" cut.

I finally upgraded to a 90 gallon 5hp speed aire compressor that should keep up with anything I could throw at it.

you could fit a few of our compressors inside the tank of that

its only a 50 litre sealy but seems to be able to keep up with a r tech cut 40 fairly easily

 

[86 slo-vo]

I previously had an 8 gallon and a 10 gallon, both were brand name compressors that couldn't handle the load of a plasma and my other tools.

Yes it is overkill for what I and most others would need, but it's worth the money to know it will last and you don't have to wait for it to build up or cool down.

 

[shenion]

Yes, had a cheap compressor. Some 1.5HP thing with no tank that was of little use other than filling tires.

Then a 3.5HP/11gal Cambell Housfeld. Still runs in my dads garage after 20 years. Was really about 2HP. About 5CFM @ 90 PSI.

Now have a Craftsman belt-driven, 5HP, 60gal picked up used. Must be 20+ or more years old now and still runs like new. Only needed a belt and oil changes over the years. It is about 11CFM @ 90 psi.

Get the best you can afford. Also keep an eye on things like Craigs list. You never know when a shop closes and sells their equipment cheap.

I think my small plasma cutter is about 7CFM. I'd want a compressor tha can deliver that without running empty or running continuously.

You can never have too big a compressor.

 

[Ragnarok]

is it really true that you need a fairly large compressor for plasma? i have a cheap but 150-200l sip and i can have it unplugged and still do fairly long cuts with my hypertherm if it's fully charged.

how do the ones with built in compressors manage if you need a big compressor?

 

[GregEng]

I think so. My 50L tank which I ended up getting really doesn't last. I went for a 3hp so charges quickly and easily keeps pressure on longer cuts with both plasma and compressor pump running. Its the largest compressor I could get space wise at the moment.

 

[Angie]

So HP is more important than litres?

 

[Ragnarok]

free air delivery is most important, litres just means it won't have to turn on as often really, and also you'lll be able to run tools that use more cfm than the compressor can supply, but only for a short time, but the bigger the tank the longer.

 

[gaz1]

ive found this thread and wondered if it can be upgraded now that more and more people have a plasma cutter and air compressor

any chance that you could say how big your compressor is and how long before your plasma cutter cuts out whilst the tank refills again i note

25 litres gives 30 sec usage time, The small ones can't keep up unless all your doing is a 6" cut.

200 litre tank, cutting a sheet of 1/8" steel from one side to the other. With a full reservoir the plasma will run for about a minute before the compressor starts up again.