Equipment World Digital Magazine
Issue link: http://read.dmtmag.com/i/506694
C ompressed air tools offer a number of ad- vantages in many con- struction applications. They are powerful and versatile and you can use them in conditions where there is water on the ground or fl ammable material nearby with out fear of shock, fi re or explosions. But if you are heading out to the rental store to get a diesel-driven air compressor, there are a few things you need to check before you go. And once you get the compressor on the jobsite, everyone who is going to use it or work around it needs to know the proper opera- tion and best safety practices. Big air compressors have unique operating characteristics and OSHA governs their safe operation in many cases. Ignorance could lead to an expensive maintenance mis- take or worse yet an accident and injury to one of your crew. Rotary screw Most engine-driven air compres- sors for construction applications use what's known as a rotary screw design. Here, twin screws interlock side by side and turn inside an increasingly narrow air chamber, and thus pressurize the air, says Rus Warner, global air products man- ager, Doosan Portable Power. The power and effi ciency of ro- tary screw compressors is such that they don't need air storage tanks. They can supply their full rated ca- pacity instantaneously on demand, even when you're working with multiple tools. They are designed for continuous duty. On newer models with electronically governed engines the engines speed up as EquipmentWorld.com | May 2015 33 contractor of the year | by Marcia Gruver Doyle | MGruver@randallreilly.com maintenance | by Tom Jackson | TJackson@randallreilly.com RENTING AN AIR COMPRESSOR Do your homework and pay attention to hoses and safety regulations The Atlas Copco XAS 185 portable air compressor puts out 185 cfm using a 49-horsepower John Deere engine. Discharge valves are on the same end as the waist level control panel and easy ac- cess to oil fi lters and the oil separator tank simplify maintenance. What's SCFM? Some manufacturers will list their air compressors' scfm, which translates into standard cubic feet per minute. But this is more of an engineering or testing spec that rates the com- pressors output at sea level and 68 degrees Fahrenheit, says Rus Warner. The cfm and scfm ratings are going to be fairly close except at high alti- tudes or extreme temperatures. If in doubt, check with your rental expert, especially for large scale or industrial applications that will require high volumes or pressure.