Low-cost additions help bottle maker manage compressed air use and energy costs on a shoestring.

Saint-Gobain Containers is a building materials company that produces high-performance materials and glass containers. In North America, the company employs 22,000 people in more than 350 locations.

Among its products are beverage bottles and other containers for the food and beverage industry. The bottle-making process requires the use of compressed air that exists, in some fashion, on or around every piece of production equipment in the plant.

Leaks, a frequent problem in compressed air systems, create inefficiencies that add to manufacturing costs. Saint-Gobain Containers set out to find an effective way to detect system leaks that did not require a large capital investment in monitoring and management equipment.

The Madera, Calif., facility, which produces millions of beverage bottles each year, designed a low-cost system using data loggers and flow meters. The company's investment of less than $5,000 in monitoring equipment is expected to yield tens to hundreds of thousands in annual savings. Saint-Gobain Containers estimates that it will reduce 10 to 50 cubic ft per min (CFM) of compressed air from each piece of equipment placed into the monitoring system.

DOE Recommends Monitoring

Compressed air is a vital utility that is used in a wide range of industrial processes. However, these systems use a significant amount of energy, so if they do not operate to full capacity—if air leaks out—energy costs can mount. As a result, the U.S. Department of Energy's Office of Industrial Technologies recommends that all facilities with compressed air systems adopt aggressive leak detection and prevention programs including quarterly system monitoring.

In addition to wasting energy, leaks create other problems. They can cause drops in system pressure, making tools operate less effectively, or leaks may make equipment cycle too frequently, resulting in higher maintenance costs and shortening equipment life span.

A compressed air system in good working order should lose no more than 10 percent of air and power capacity, but it is not unusual for systems to lose as much as 20 to 30 percent. Leaks are most likely to occur at joints and fittings and can often be averted through a simple tightening or replacement of connections.

Detecting Equipment Leaks With Data Loggers

In complex or large systems, leakage monitoring and detection systems can be costly and time consuming. Knowing this, Greg Rhames, an energy engineer at Saint-Gobain Containers Madera, Calif., plant, set out to find a low-budget way to find and reduce energy waste from three 1,250 hp compressors that run 24/7.

Rhames decided to pursue what he describes as monitoring from “an equipment-based perspective.” This runs contrary to the more common industry method of placing large meters of different types close to the supply side of a compressed air system. Rather than monitoring the total system output, he decided to analyze the performance of individual pieces of equipment, pinpointing problems at the source through measurements taken with data loggers.

“Instead of looking at this from 300,000 feet, we were looking at it from 1,000 feet,” he says. “You can get solid results by going to the equipment and working your way back versus monitoring at the supply side. If you monitor from the supply end, you have no resolution on issues causing the air leaks downstream.”

Monitoring Systems Make Process More Efficient

Rhames devised a monitoring system that uses an energy logger, a portable data logger which includes snap-in modules that convert signals from nearly any type of sensor. The 15-channel data logger can measure compressed air, gauge pressure, kW/hr output, voltage, current, air velocity, temperature and a range of other parameters. For Saint-Gobain Containers' purposes, Rhames needed the data loggers to measure the CFM consumption of every piece of equipment in the plant that used compressed air. To accomplish this, Rhames installed compressed air flow meters with remote displays, which he connected to the modules. As the project continues, additional meters will be installed at each compressed air receiver throughout the plant to allow departmental isolation and monitoring of system air pressure.

Rhames placed two data loggers in one of the centralized equipment control panels. During installation, he performed a 10-minute logging test and gathered the results to verify that all the components were operating correctly. He then redeployed the logging devices and left them to record for 24 hours. He recorded the air flow measurements every two seconds.

Since the data loggers are portable, he was able to unplug the modules, remove the loggers and bring them into his office to download the data into a graphing and analysis software package. The software provided a quick read out of the collected data, which could then be exported to Microsoft® Excel, which he used to manipulate the information. Using both spreadsheet and graphical formats, he set a baseline measurement, studied the effects of various corrective actions, compared historical records and established benchmarks. Most of the machinery cycles were between 2 to 15 seconds, depending on what was occurring. By stretching the data over the course of the day, anomalies in the system became apparent.

The individual pieces of equipment should lose no more than 2 to10 CFM. If there is a loss of more than 10 CFM, “you should really analyze the equipment and see where you're losing air. Find it, fix it and bring it back down to tolerance,” Rhames says.

“The data so far shows we're losing 20 to 30 CFM because of leaks,” he adds. “It is amazing how much waste occurs on one piece of equipment. The data loggers make it immediately evident.”

Large Savings Achieved Quickly

Using the energy logging equipment, Saint-Gobain Containers identified the worst compressed air leaks and repaired them, resulting in a 10 CFM decrease in compressed air waste. Rhames calculates that the facility will save $2.24 for every CFM of High Pressure air preserved. As a result, “the savings could be huge—possibly tens to hundreds of thousands of dollars annually,” he says.

By working on a small budget, Rhames avoided the delay common in most corporations when requests are made for large capital expenditures. He was able to get the project up and running in days, rather than the standard months or years. The data provided by the data loggers allowed for a quick reaction to correct the leaks. As a result, Saint-Gobain Containers was able to start saving energy, and money, sooner than it would have with a larger, more costly system.

Use of the data logger will now be standard operating procedure at the facility. Data gathered and compared, during and after leaks are found and repaired, will be applied to achieve a standard, minimum, CFM-consumption benchmark for all similar equipment.

The data logger system proved to be an effective way to provide real-time analysis that was previously only attainable with a larger, much more expensive system. The project showed that a large industrial facility can institute a comprehensive, compressed air monitoring system and a compressed air waste reduction system, with economical, equipment-level monitoring and logging devices.

Pumps & Systems, October 2010