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Tinker works to conserve air supply

Steve Atchley, with the 72nd Air Base Wing Civil Engineering Directorate, walks by a 700 horsepower air compressor in the Bldg. 9001 Central Utilities Plant. Two existing 350 horsepower compressors and another 700 horsepower compressor coming soon send uninterrupted air to mechanics who depend on the air to power tools and machinery throughout the complex. The cylindrical tanks dry the air before sending it. (Air Force photo by Margo Wright)

Steve Atchley, with the 72nd Air Base Wing Civil Engineering Directorate, walks by a 700 horsepower air compressor in the Bldg. 9001 Central Utilities Plant. Two existing 350 horsepower compressors and another 700 horsepower compressor coming soon send uninterrupted air to mechanics who depend on the air to power tools and machinery throughout the complex. The cylindrical tanks dry the air before sending it. (Air Force photo by Margo Wright)

TINKER AIR FORCE BASE, Okla. -- If you can hear a leak of compressed air, inert gas or steam, "That's probably not good," quips Paul Garnaas, Resource Efficiency Manager in the 72nd Air Base Wing Civil Engineering Directorate.

Compressed air performs myriad functions at Tinker Air Force Base. It operates machine tools that are used to install and remove fasteners and rivets. It powers winches, robotics, and aircraft paint sprayers. It's used in hydraulic scaffolds that mechanics employ to repair jet engines and military aircraft, for cleaning benches and other work areas, for clean-up of parts, and in heating, ventilation and air conditioning controls.

This is, after all, an aircraft maintenance depot. Consequently, leaks are a continuous problem, "something we fight all the time," Mr. Garnaas said. Objects such as hoses, pipes, connections and elbows inevitably wear out, he noted. "These are the first things that fail."

Compressed air is easy to control and simple to operate, but it's one of the most expensive utilities, "way above natural gas or chilled water," Mr. Garnaas said. "You expend about eight times the energy for every pound of work produced from compressed air," the North Dakota State University mechanical engineering graduate said.

A leak of compressed air or inert gas can be costly in more than one way.

Compressed air costs an estimated 23 cents per 1,000 cubic feet, Mr. Garnaas said. Even at that nominal cost, an air leak of 3 cubic feet per minute multiplies to 1.5 million cubic feet per year, at an estimated cost of $350,000.

In comparison, argon and helium cost $22 per 1,000 cubic feet, and nitrogen costs $56 per thousand, Mr. Garnaas said.

Consequently, repairing a leak quickly can result in a substantial avoided cost.

A leak also allows moisture to enter hoses and lines, and thus to foul machines and tools, Mr. Garnaas pointed out. At Tinker, compressed air is warmed with refrigerated and desiccant dryers, he said; a leak, though, enables outside, humid air to enter the system.

According to Allen Logan, a Predictive Maintenance technician in the 76th Maintenance Support Squadron, leaks in argon and compressed air lines that were found by the PdM unit in 2010 and then repaired saved an estimated $800,000 -- and resolved at least one perplexing production problem.

In an Oklahoma City Air Logistics Complex welding shop, several welds performed by veterans who'd been welding for 20 years or more were deemed unsatisfactory. The mystery was solved when an ultrasound device was used on the welding system; a leak found in an argon gas line was pulling in air and moisture that spoiled the welds, said David Robinson, chief of the Equipment Engineering Flight in the 76th MXSS. Patching the leak improved the welds and derailed plans to purchase an auxiliary argon gas storage tank, he said.

Ultrasound equipment is used to detect various leaks such as vacuum, steam, inert gases and compressed air leaks, all of which are "big money losers," PdM Technician Mike West said.

Do not use your hands to inspect an air or gas leak, Mr. Garnaas warned. A high-pressure compressed-air leak could easily damage your flesh, and leaking steam could burn you.

An air or gas leak should be reported to Tinker Support Services at 734-3117, "or tell your supervisor," Mr. Garnaas advised.

"The biggest issue we have is simply getting people to notify someone when they hear one of those leaks," he added. "If it's hissing, it shouldn't be doing that."