The compressed air industry is taking a step that will clear the air about the performance of its equipment. For the first time, many compressed air equipment manufacturers will submit their 50 hp to 200 hp lubricated rotary-screw compressors and 200 cfm to 1,000 cfm refrigerated air dryers to an independent laboratory for performance testing.The Compressor Distributors Association (CDA) led the charge that moved the industry to this decision. The CDA, a group of industrial air compressor distributors representing different manufacturers, was formed to sponsor the Compressed Air Challenge (CAC) and to have a voice in its operations. The CDA is represented on both the CAC Board of Directors and its Product Development Committee.
After several meetings, the CDA began a series of discussions about how the organization might improve the industry. The group agreed that a need existed for accurate and independently verified performance data on the equipment they provide to end users. The motivation is that distributors are being pressured to provide much more accurate system analysis and recommendations than have been required in the past.
With the ability to be accurate comes an increasing need for accurate and dependable input information. The commitment to this need prompted CDA to fund an independent, blind testing program for seven manufacturers’ 50-hp lubricated rotary-screw compressors against their published performance information. Finding a capable, well-equipped laboratory was a formidable task, as was securing the use of seven competitive machines for the short time window available.
Test results are presented as percentage variance from the published data. With test data in hand, CDA approached the Compressed Air Challenge Board and the Compressed Air and Gas Institute (CAGI) to illustrate the need for universal testing. While there had been many discussions within the industry about independent testing, nobody seemed to be making tangible moves in that direction. CAGI members had adopted a Compressor Data Sheet to report performance data in accordance with ISO 1217, but many manufacturers hadn’t made this information readily available. After CDA’s presentations, these groups, along with ASSERTI, endorsed the value of outside verification of product performance.CAGI took the lead and worked with other organizations to formulate the testing program. Three years later, after a lot of cooperation and hard work, the program is now in place.
What’s being tested?
The CAGI compressor performance testing includes rated capacity (cfm) at full-load operating pressure (spi), total input power at rated capacity at full operating pressure (kW) and specific package power (kW/100 cfm). Refrigerated air dryers are tested for flow (scfm), outlet pressure dewpoint (degrees F), pressure drop (psid), total input power (kW) and specific package power (kW/100 cfm).
The lab will administer the program, contact the manufacturer and select a specific machine to be tested. Their random selection will come either directly from manufacturer inventory or from a distributor's stock. After the test, the manufacturer will be advised if the machine passed or failed.
Once a machine tests successfully, compressor and air dryer manufacturers will be entitled to use the CAGI Performance Label. CAGI manufacturers whose equipment fails the test will have an opportunity to correct the problem. If it can’t be corrected, the manufacturer isn’t entitled to use the CAGI label. The CAGI Web site will post a notice of non-performance, thus putting the manufacturer at a significant marketing disadvantage. The program also is being offered to manufacturers that aren’t CAGI members.
What it means to you
This testing program allows users to evaluate the data presented with new equipment bids and to feel more confident with purchasing decisions. In the most basic comparisons of machines, end users ask:
- How much compressed air will this machine provide compared to its capital cost?
- How much energy will it consume per unit of compressed air (cfm/bhp)?
- How much will it cost to operate?
Answering these and similar questions always has been a fundamental step in the decision to purchase a compressor or dryer. In the past, end users could only rely on answers based solely on the information the manufacturer provided. This typically included only the full-load volume (cfm), horsepower required at full load and horsepower at an unloaded state. In sales presentations, this information most often is coupled with discussion of the control system in an attempt to evaluate the machine’s efficiency while operating at partial load, often leaving room for substantial doubt. Soon, most of these performance claims will be substantiated and reported on the CAGI Web site.
After purchase, a machine’s full-load and partial-load efficiency has been difficult to verify and often faded to a point of little interest. The result has been many, if not most, systems are unmonitored and operating with unnecessary energy consumption. Further, system changes with air users being added or removed, pressure increased or reduced, production hours increasing or decreasing, and evolving leaks can make dramatic changes in the energy consumed. Without a reliable baseline for comparison, it’s been difficult to quantify the effects of these changes.
A system analyst now can easily evaluate a machine’s performance with modern data collection tools, but reliable equipment performance information is still essential. With good data, knowledgeable compressed air system analysts can verify system performance and easily determine if the system is operating efficiently. This information also can determine if any system changes would result in substantial energy savings.