Compressed Air Leak Detection Survey

 

Air compressor motors are typically an industrial plants single largest user of electricity. For many manufacturers  compressed air represents the second or third highest utility cost in their facility.

 

According to the US Department of Energy [Compressed Air tip sheet no.3]: “Compressed air leaks are a significant source of wasted energy in a compressed air system, often wasting as much as 20-30% of the compressors output”

 

According to an SEI Case Study of two leak detection surveys carried out at two different plants in Ireland it was determined that annual savings in compressor output of 29% and 11% respectively could be achieved by carrying out a leak detection programme. To read this case study click here

 

In addition to being a source of wasted energy, leaks can also contribute to other operating losses. Leaks cause a drop in system pressure, which can make air tools function less efficiently, adversely affecting production. In addition, by

forcing the equipment to cycle more frequently, leaks shorten the life of almost all system equipment (including the compressor package itself). Increased running time can also lead to additional maintenance requirements and increased unscheduled downtime. Finally, leaks contribute to unnecessarily  increased compressor capacity.

 

Capstone Energy Management offer a Compressed Air Leak Detection Survey.

Using ultrasonic leak detection equipment we will identify and tag all leaks in your compressed air system. A comprehensive report is then compiled detailing the location and quantity of leak flow (CFM) of each individual leak together with the associated cost that each leak incurs. This information is invaluable to maintenance and facility engineers,  providing them with the necessary information to implement an effective and proactive leak repair program.

 

 

 

Annual cost of Air leaks:

 

 

 

 

 

 

 

 

 

 

 

 

* Based on specific package input power at normal working pressure = 7.16kW/m3/min

Electricity AUC= 11.4c/kWh

Example

A chemical plant undertook a leak-prevention program following a compressed air audit at their facility. Leaks, approximately equivalent to different orifice sizes, were found as follows: 100 leaks of 0.5mm at 7 bar gauge (psig), 50 leaks of 1.5mm at 7 barg, and 10 leaks of 6mm at 7 barg.

 

Calculate the annual cost savings if these leaks were eliminated. Assume 7,000 annual operating hours, an average unit cost electric rate of €0.12 kilowatt-hour (kWh), and compressed air generation requirement of approximately 7.16 kilowatts kW/m3/min.

 

Cost savings = # of leaks x leakage rate (L/sec) x kW/m3/min x # of hours x €/kWh x 0.06

Using values of the leakage rates from the above table and assuming sharp-edged orifices:

 

Cost savings from 0.5mm leaks = 100 x 0.2 x 7.16 x 7,000 x 0.12 x 0.06  = €7,217

Cost savings from 1.5mm leaks = 50 x 1.8 x 7.16 x 7,000 x 0.12 x 0.06= €32,478

Cost savings from 6mm leaks = 10 x 28 x 7.16 x 7,000 x 0.12 x 0.06 = €101,042

Total cost savings from eliminating these leaks = €140,737

 

Note that the savings from the elimination of just 10 leaks of 6mm account for almost 70% of the overall savings.

 

 

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Hole diameter

Air leakage at 7 barg

Power to Air leaks*

Cost of leak /year

0.5mm

0.2 Litre/sec

0.0858 kW/h

€85.10

1.5mm

1.8 Litre/sec

0.7722 kW/h

€765.67

3.0mm

7.1 Litre/sec

3.0459 kW/h

€3,020.92

6.0mm

28 Litre/sec

12.012 kW/h

€11,913.50