The Problem with a Compressor Leak
The U.S Department of Energy Efficiency and Renewable Energy stated a typical plant that has not been maintained will likely have a compressor leak rate of 20% of the total compressed air production capacity, and proactive leak detection and repair can reduce leaks to 10% of compressor output. Leaks not only cause energy loss, they can lead to other operating losses. If a system has greater than 10% leakage there are opportunities for improvement.
A compressor leak create a drop in system pressure and cause tools to operate less efficiently, run longer, and shortens the life span of the tool. Increased runtime adds more stress to the system and can lead to more maintenance and unscheduled downtime.
Common Industrial Compressor Leak Sources
The major problem areas for a compressor leak are pressure regulators, couplings, hoses, tubes, fittings, shut-off valves, pipe disconnects, pipe joints, thread sealants, and open condensate traps. Many leaks are caused by poor, or improperly applied thread sealant. Machinery vibrations can cause the seal around joints to fail over time. Vibrations can occur from normal machine operation, or an imbalance with fan blades or motor mounts. Equipment that is connected to the system but not in use can be another source of leaks.
The best way to detect a compressor leak is to use an ultrasonic acoustic detector, which is capable of detecting the high frequency sound of high pressure leaks. Leaks move from an area of high pressure laminar, or streamline flow, to a low-pressure turbulence. Turbulent air flow contains eddies, or pockets of fluid particles which backflow and cause lateral mixing. Turbulence creates audible and inaudible frequencies, and ultrasound short wave signals; loudest at the leak site. The ultrasonic detector filters out the audible sounds and hones in on the short wave length frequencies, allowing leak detection while the system is operating.
If an ultrasonic acoustic detector is not readily available, leaks can also be detected using a spray bottle of soapy water and applying the solution to the joints and fittings. If there is a leak the soapy water will bubble. This is a reliable and economical technique.
Fixing a compressor leak can be as simple as tightening a connection, or more complicated and require replacing faulty equipment. Purchase high quality system components including, hoses, fittings, disconnects, and tubing, and install properly with the appropriate thread sealant. Non-operating equipment should be isolated from the system with a valve. Reducing system pressure to the lowest practical range will slow the flow rate and can also reduce leaks.
Establishing a Compressor Leak Prevention Program
The U.S Department of Energy suggests incorporating a leak prevention program into a facility operation plan. In general there are two types of leak prevention programs:
- Seek & Repair Program – Find the leak and repair it immediately.
- Leak Tag Program – The leak is identified, tagged, and logged for repair at a later time.
The best approach will likely include both processes, and depends on the type and size of the facility, and the work and maintenance practices.
The plan should include setting a target for cost-effective leak reduction, leak identification, tagging, repair, tracking, verification, and employee education. Fixing leaks once is not enough. Once a repair is made the system will need to be re-evaluated. Facility managers should consult a controls specialist to make any necessary compressor control adjustments. Alternative energy sources should be considered for some equipment, and compressors should be turned off if possible.