Panel & Paint

Motor Equipment News - - CONTENT -

We don’t think any­one is go­ing to ar­gue with the state­ment “ev­ery panel beater re­lies on his com­pres­sor”. Whether it’s for clean­ing, spray paint­ing, or driv­ing tools and other equip­ment, the com­pres­sor is an in­te­gral part of ev­ery panel beater’s busi­ness.

Most air com­pres­sors used to­day are of a sim­ple ba­sic de­sign, us­ing a re­cip­ro­cat­ing pis­ton, sim­i­lar to that used in an in­ter­nal com­bus­tion en­gine, but in­stead of pro­vid­ing power, is it­self pow­ered by an elec­tric mo­tor to com­press air which it then stores in a tank un­til an air de­vice is used.

The ben­e­fits of the tank are that the air is re­leased at a con­stant pres­sure, and it can be “topped up” without in­ter­fer­ing with the flow of air be­ing used.

All that is pretty much ba­sic stuff and the fact is that the ba­sic de­sign of com­pres­sors hasn’t changed much over the years.

Ex­cept, that is, for the ad­vent of ro­tary vane com­pres­sors.

I re­cently came across an in­ter­est­ing piece from US com­pany Mat­tei, which has been mak­ing air com­pres­sors since 1919.

Says Mat­tei:” The tra­di­tional way of sup­ply­ing air through­out auto re­pair and body shops was with pis­ton com­pres­sors. Th­ese ma­chines are typ­i­cally less ex­pen­sive to pur­chase up-front than other com­pres­sors, which led to their sta­tus as the ‘in­dus­try stan­dard.’ Wait­ing for an air com­pres­sor to “kick-in” was an un­der­stood prac­tice, as pis­tons had to work up to a pres­sure, shut off, then build that pres­sure back up again once the pres­sure in the tanks went down.

“How­ever, as man­u­fac­tur­ers sought to lower costs, they made the size of the pis­ton pumps smaller and less ro­bust. While man­u­fac­tur­ers may have as­sumed th­ese changes would have lit­tle im­pact on the ma­chine, in re­al­ity, they sig­nif­i­cantly al­tered the prod­uct.

“To­day’s pis­tons have pumps run­ning at a much higher speed,” Mat­tei quotes a cus­tomer, “and th­ese com­pres­sors are not de­signed to run as hard or as fast as how they’re be­ing used.

“Be­cause of this, we’re com­monly see­ing the valves and pumps fail much ear­lier. The crankshafts are also break­ing be­cause the pumps are so over­worked.”

And we all know how noisy pis­ton com­pres­sors are; you can’t in­stall them in the same room where peo­ple are work­ing.

How­ever, ro­tary vane com­pres­sors are much qui­eter-run­ning. At the same time, says Mat­tei, not only can vanes op­er­ate in­ter­mit­tently to meet the needs of auto re­pair shops, they can also run flat-out, non-stop to read­ily meet the de­mands of high out­put col­li­sion re­pair shops. Other ad­van­tages cited by Mat­tei in­clude: En­ergy ef­fi­ciency: over the ser­vice life of an air com­pres­sor, 83 per­cent of to­tal air com­pres­sor costs are re­lated to en­ergy usage. In com­par­i­son, pur­chase price only re­flects 11 per­cent of the to­tal cost of own­er­ship and main­te­nance only rep­re­sents six per­cent. Mat­tei says the ad­vanced de­sign of ro­tary vane com­pres­sors cre­ates a near-per­fect air­tight seal in the ro­tor sta­tor unit, which en­hances vol­u­met­ric ef­fi­ciency and re­duces the amount of en­ergy re­quired to de­liver the air. This means vane com­pres­sors can achieve me­chan­i­cal ef­fi­cien­cies of up to 90 per­cent.

Duty cy­cle: the duty cy­cle of a com­pres­sor is the max­i­mum rec­om­mended per­cent­age of time it should be com­press­ing air be­fore un­load­ing or shut­ting down to pre­vent over­heat­ing, com­po­nent wear, and oil car­bon­i­sa­tion and break­down. When sized prop­erly, a typ­i­cal pis­ton com­pres­sor has a duty cy­cle of 50 per­cent and no more han 70 per­cent to en­sure the pump runs cool and to pre­vent valve prob­lems and pre­ma­ture wear to the com­pres­sor pump.

In con­trast, says Mat­tei, a ro­tary vane com­pres­sor can run at 100 per­cent of its rated ca­pac­ity for hours on end without any harm or dam­age to the vane airend. A prop­erly sized ro­tary vane com­pres­sor of­ten af­fords the user the abil­ity to se­lect a com­pres­sor one size smaller than a pis­ton style com­pres­sor. This saves both on pur­chase price and on elec­tric­ity con­sump­tion.

Op­er­at­ing tem­per­a­tures: heat = wasted en­ergy, and high dis­charge tem­per­a­tures can also cre­ate mois­ture lev­els that can af­fectt spray booths and pneu­matic equip­ment. Ro­tary com­pres­sors av­er­age be­tween 76 deg.C and 83 deg.C, whereas pis­ton units can run as high as 204 deg.C. And ro­tary com­pres­sors have an air-cooled af­ter­cooler which re­moves 65 per­cent of the con­dens­able mois­ture.

Air qual­ity: Mat­tei says ro­tary vane com­pres­sors in­te­grate high-ef­fi­ciency fil­tra­tion to en­sure as lit­tle as 1 – 3 ppm of oil car­ry­over en­ters the air sys­tem to pre­vent con­tam­i­na­tion of equip­ment or pro­cesses. Tra­di­tional pis­ton com­pres­sors can pass 25 ppm or more, par­tic­u­larly if they run un­loaded for pe­ri­ods of time.

Life ex­pectancy: ro­tary vane com­pres­sors are de­signed to op­er­ate for up to 100,000 hours, while Mat­tei says it is not un­com­mon for the sys­tems to ex­ceed this.

More info: www.mat­te­

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