Doe Comp Air

Steam

Motors

Compressed Air

Minimize Compressed Air Leaks
Suggested Actions
• Fixing leaks once is not enough. Incorporate a leak prevention program into your facility’s operations. It should include identification and tagging, tracking, repair, verification, and employee involvement. Set a reasonable target for costeffective leak reduction—5-10% of total system flow is typical forindustrial facilities. • Once leaks are repaired, re-evaluate your compressed air system supply. Work with a compressed air systems specialist to adjust compressor controls. Also look at alternatives to some compressed air uses. If a compressor can be turned off, benefits include cost savings and a system backup. Leaks are a significant source of wasted energy in a compressed air system, oftenwasting as much as 20-30% of the compressor’s output. Compressed air leaks can also contribute to problems with system operations, including: • Fluctuating system pressure, which can cause air tools and other air-operated equipment to function less efficiently, possibly affecting production • Excess compressor capacity, resulting in higher than necessary costs • Decreased service life and increasedmaintenance of supply equipment (including the compressor package) due to unnecessary cycling and increased run time. Although leaks can occur in any part of the system, the most common problem areas are: couplings, hoses, tubes, fittings, pipe joints, quick disconnects, FRLs (filter, regulator, and lubricator), condensate traps, valves, flanges, packings, thread sealants, and point of use devices.Leakage rates are a function of the supply pressure in an uncontrolled system and increase with higher system pressures. Leakage rates are also proportional to the square of the orifice diameter. (See table below.)

References
Improving Compressed Air System Performance: A Sourcebook for the Industry, Motor Challenge and Compressed Air Challenge, April 1998.

Leakage ratesa (cfm) for differentsupply pressures and approximately equivalent orifice sizesb
Pressure

Orifice Diameter (inches) 1/64 0.3 0.33 0.37 0.41 0.49 1/32 1.2 1.3 1.5 1.6 2.0 1/16 4.8 5.4 5.9 6.5 7.9 1/8 19.2 21.4 23.8 26.0 31.6 1/4 76.7 85.7 94.8 104 126 3/8 173 193 213 234 284

(psig) 70 80 90 100 125
a

Training
• Fundamentals of Compressed Air Systems - 1 day • Advanced Management of Compressed Air Systems -2 days Offered by the Compressed Air Challenge. Call the OIT Clearinghouse or visit the BestPractices Web site (www.oit.doe.gov/bestpractices) for the latest schedule and locations.
For additional information on industrial energy efficiency measures, contact the OIT Clearinghouse at (800) 862-2086.

For well-rounded orifices, multiply the values by 0.97, and for sharp-edged orifices, multiplythe values by 0.61. b Used with permission from Fundamentals of Compressed Air Systems Training offered by the Compressed Air Challenge™.

Leak Detection
The best way to detect leaks is to use an ultrasonic acoustic detector, which can recognize high frequency hissing sounds associated with air leaks. These portable units are very easy to use. Costs and sensitivities vary, so test before youbuy. A simpler method is to apply soapy water with a paintbrush to suspect areas. Although reliable, this method can be time consuming and messy.

OFFICE OF INDUSTRIAL TECHNOLOGIES ENERGY EFFICIENCY AND RENEWABLE ENERGY • U.S. DEPARTMENT OF ENERGY

Example
A chemical plant undertook a leak prevention program following a compressed air audit at their facility. Leaks, approximately equivalent todifferent orifice sizes, were found as follows: 100 leaks of 1/32" at 90 psig, 50 leaks of 1/16" at 90 psig, and 10 leaks of 1/4" at 100 psig. Calculate the annual cost savings if these leaks were eliminated. Assume 7000 annual operating hours, an aggregate electric rate of $0.05/kWh, and compressed air generation requirement of approximately 18 kW/100 cfm. Cost savings = # of leaks x leakage...