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 Welding-site conditions and welding-wire diameter govern efficiency and size of power supply required for a job. Select a 100-A unit that runs from single-phase 115-V input for low-duty-cycle welding of sheet to l/s in. thick, feeding wire to 0.030-in. diameter. Medium-duty power supplies, 150-200 A, normally aor take single-phase compressor 220-V input to weld steel to 3/16, in. and 0.035-in. wire at low-duty cycles. For high-duty cycles, as hoses in mechanized welding, aor select a 250-A machine, single or three-phase input at various voltages-these weld material to 1/2 in. thick with wire as large as 0.045-in. diameter. Taking three-phase input only and wire up to compressor 1/6-in. diameter, hoses 400-A units serve for mechanized continuous-welding applications. For pulsed GMAW, shops use inverter and transistor power sources, constant-current or constant-voltage, that offer independent setting of pulse parameters. They employ aor synergic controls preprogrammed for a range of wire-feed speeds-the operator sets only one dial, for average current. Welding Torches and GunsUsed for shielded-metal-arc compressor welding, torches (electrode holders). manually controlled, grip hoses ends of electrodes, also called rods-pinch type and collet type are common.GMAW and FCAW guns come in pistol grip, goose-neck, and inline styles, the latter used for mechanized welding. Knowing the wire diameter, select a gun rated slightly higher than the welding current to be used. Duty-cycle ratings are usually aor given for C[O.sub.2] shielding--air or C[O.sub.2] cooling arc usually sufficient for welding at up to 600 A at less than 100 percent duty. Higher amperages require water cooling--high-amperage guns come with tubing for water cooling. Hand-held, mounted on a robot arm or fixed within a mechanized welding setup, guns guide filler wire and shielding gas into the weld puddle. Shielded-Metal-Arc Welding (SMAW, STICK)AWS (American Welding Society) A5 specifications Set standards for electronics for SMAW of carbon, stainless, and low alloy steels; aluminum copper, and nickel and their alloys and weld-surfacing. Designations for covered electrodes carry the prefix ''E''. Packaged to AWS specifications, electrodes come in boxes, cans, or other containers, labeled with their AWS specification and trade name, compressor quality control (heat or lot) number, supplier name, diameter and length, and weight of contents. Specifications require that every hoses electrode bc marked for identification near with its numeric designation aor the grip end.To select a covered compressor SMAW electrode, consider these hoses factors, in approximate order of importance. Searching for accessories for your air compressor? We offer the best selection of cheap air compressor accessories on the internet. Check out our website for great deales on all of our air compressor accessories!
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