Compressed air systems are the heart of many production and processing facilities—compressors beating out a healthy air flow through multiple branches of distribution piping to a myriad of critical equipment. Taking care of compressed air systems is, therefore, necessary to ensure they remain healthy and energy waste is minimized.
There are two primary considerations gauging the health of a compressed air system: leaks and waste.
Leaks happen
Air leaks are common occurrences that waste compressed air and cause compressors to operate unnecessarily. Compressed air distribution piping can often be long and stretch from one end of a facility to the other with numerous joints and points of connection. Every interface has the potential to become a leak. Leaks in compressed air systems are analogous to open windows when the furnace is running–even if the furnace can maintain the setpoint there is significant wasted energy and expense. Likewise, leaks cause unnecessary compressor operation, wasting energy, increasing costs, and causing premature wear in the compressor. If the leak rate grows too large it can compromise the ability of the compressors to maintain the required pressure in the system, resulting in equipment degradation and potential quality problems.
The reality is that compressed air system maintenance and leak detection are critical to manufacturing and processing success and therefore must be prioritized.
In fact, improving compressed air system performance isn’t just about finding leaks and maintaining a healthy system. The U.S. Department of Energy (DOE), as part of their Better Plants Program and the Compressed Air Challenge (CAC) have focused quite a bit of attention on managing compressed air system leaks. Why? Because compressed air system leaks waste energy (resulting in increased greenhouse gas emissions) and lead to increased cost of operation.
Waste not
There are essentially two sides of a compressed air system – the supply side and the demand side. The supply side is what the system can give, and the demand side is what the connected equipment requires to optimally function. The goal in designing the compressed air system for a facility is to balance supply and demand, ensuring that demand can be fulfilled with room to grow, but not so much that excess capacity leads to inefficiency. An oversized compressor can also waste energy.
According to the DOE, compressed air systems can lose 20 to 30 percent of their output from leaks alone. Why is that bad? Well, not only is the energy wasted, which still needs to be paid for regardless of how it was or was not used, but the system often must compensate for that lost output by increasing production and throughput to meet the demand or else leave the system underserved. The goal should always be decreasing energy intensity and increasing throughput. (Note that, according to the DOE, a 1/16-inch sized leak at a flow rate of just 6.5 cfm will cost $1,046 per year. That’s just one, very tiny leak at a low-flow rate.)
Compressed air system checklist
In the “Improving Compressed Air System Performance” sourcebook, the DOE/CAC provide a checklist for establishing a leak prevention program. This program helps companies minimize the impact of leaks in their compressed air systems—some of the same recommendations they provide to those companies participating in their Better Plants Program. Here are the 10 items on the checklist (for more details, download the guide):
- Baseline compressed air usage.
- Establish leak loss.
- Determine cost of air leaks.
- Identify leaks.
- Document the leaks.
- Prioritize leak repair.
- Adjust controls.
- Document repairs.
- Compare baselines and publish results.
- Start over again.
As part of the Better Plants Program, the DOE will loan participating companies instruments they can use to gauge their pre- and post-program energy mastery. One tool is the Fluke ii900 Industrial Acoustic Imager, which helps participants meet several of the checklist requirements, such as establishing leak loss, determining the cost of air leaks, identifying leaks, documenting the leaks, and prioritizing the repairs.
Any business that uses a compressed air system can benefit from following these guidelines to reduce waste and optimize the efficiency of their system. It’s not the size of the business, but rather the size of the leaks, that determine just how effective this program is for a given company. After all, these systems were installed with the intention of lasting a long time under some of the most demanding pressure—they deserve to be properly maintained.