Plasma air compressor question

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I have a simple (naive) question about plasma cutters. I don’t own one but see some good prices once in a while on used units.Can I air up my 80 gallon air compressor, set the regulator to what ever psi the plasma requires and turn off the compressor and then cut with the plasma cutter? Will the plasma cutter shut off when the psi drops to a certain range?Is this potentially harmful to the plasma cutter?The reason for the question is I have a 40-50 amp breaker in the garage and running both the compressor and plasma would probably trip the breakerDave ReberWadsworth Ohio
Reply:Yea you can do that.  So long as your tank pressure doesn't drop lower than what you're using for your plasma cutter, you'll be fine.  Once you actually start dropping pressure to the plasma cutter you'll see the plasma arc become shorter and shorter, and consequently will take longer to cut and you might get a lot of metal dross on the backside of the cut if the air is too too low.
Reply:I'm pretty sure they have pressure switches that shut them down when air pressure is too low.
Reply:My TD cutmaster will shutdown and go into alarm mode if it looses it's air. It will not re fire till air pressure goes back up. The TD cutmaster machines also have a built in air pressure regulator.JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:Depending on the compressor, the plasma cutter, and the amperage being used to cut you may squeak by on your 50 amp outlet. Just keep a flashlight in your pocket. Your plan of charging the compressor is a good one. No issues... most plasma cutters will turn off when the air pressure drops too low. I know both my TD cutmasters do.A few years ago I picked up an upright 80 gallon tank off CL for free. I use the tank for additional air storage and to give the air some space to cool.Of course you really should get the compressor on it's own circuit... that way you can weld, cut, and grind without fear of losing the lights.
Reply:My hypertherm pm65 has a low pressure shut down. My 80 gal tank will make quite a few cuts when I forget to turn it on.Millermatic 252millermatic 175miller 300 Thunderboltlincoln ranger 250smith torcheslots of bfh'sIf it dont fit get a bigger hammer
Reply:Thanks guys. I check out craigslist once in awhile and see some good deals on plasma cutters, they sure are fun to play with.Dave ReberWadsworth Ohio
Reply:I have run my Powermax 30 plasma on a dedicated 230v. line, and a 80 gl. 2 stage 230v.compressor on a dedicated line.  50amp breaker as a main on the subpanel in the pole barn. The both lines are protected width 30 amp breakers   No issues.
Reply:You will get quite a long cutting time out of an 80 gal. tank, especially if the compressor has a 2-stage pump (175psi tank pressure) vs a single-stage pump (125psi tank pressure). OTOH, i ran a MAX42 (an older, less efficient forerunner of the Powermax 45) and a 2-stage compressor together on a 50A breaker for years and the breaker never blew.Try it first, if it blows the breaker then you can go with your plan.JohnA few weldersA lot of hammersA whole lot of C-clamps
Reply:Thanks for the inputDave ReberWadsworth Ohio
Reply:I was in a similar boat with an 80 gallon 7.5hp compressor, and an old 40A plasma cutter that drew something like 37A 240V at the plug.  50A breaker feeding the garage panel.I never shut the switch on the compressor, and when I heard the compressor start, I would just take a break with the plasma, and I never tripped the breaker.  Even with the starting current of the motor, it just wasn't quite enough draw to trip the instantaneous on the breaker, and it takes several seconds of draw to trip the breaker on the thermal.  So if you pay attention and stop cutting when the compressor kicks in, you'll probably be fine.I've since replaced the plasma with one that draws less power (with more cutting ability).  Newer plasma cutters are much more efficient.
Reply:Another point I neglected to mention:Most plasma cutters do have a pressure switch that shuts off the cutting when the pressure is too low. However, by the time it shuts down, the air pressure is low enough to reduce cut quality and shorten the life of the consumables. For best performance you should always have at least the manufacturer's recommended pressure at the machine's input.JohnA few weldersA lot of hammersA whole lot of C-clamps
Reply:You will find that when the pressure is between cut pressure and low pressure shut down.The tip will ware very fast and if you cut very long near the low pressure point. It is very hard on the torch and plastic handle. The torch is brass, so overheating will damage the o-rings and insulators.
Reply:Hi, in the dim and distant past I seem to recall something of a similar nature, except it was a single phase low amperage environment.There was a small air compressor that supplied air at about 200 PSI on line, no stored air, flow rate quite low.I don't know what the flow rate is for a typical (?) plasma cutter, but I think the flow continuous is a lot less than a compressor that has to fill a large tank very quickly.......IE, if you were using the Plasma you wouldn't have the compressor running all the time....it would just suddenly cycle on for a time and then off when the tank was up to pressure....if it ran continuously when cutting then the compressor is too small.I have heard of a plasma cutter with a built in compressor that runs direct on line with no stored pressure etc.....would this be a solution?If the tank was up to pressure, what size compressor would be needed to just continuously replace the air used as opposed to pumping it rapidly up once it was down on pressure.An air tool may use air at a high pressure, but the pump size is determined by the flow rate, (once the tank is up to pressure).Ian.