- Buyer's Guide
Every maintenance department seeks reduced maintenance costs, increased equipment utilization and improved equipment reliability. To achieve this, maintenance personnel often look to upgrade the plant’s lubricants to the latest technology. However, they often find it difficult to immediately justify the higher cost of the oil because maintenance savings cannot be shown prior to purchasing the oil. Furthermore, records are not always user-friendly, making it difficult for personnel to accurately document the savings that result once the high-performance oil is used.
Energy Cost - A New Perspective
Some innovative maintenance personnel have successfully worked within this Catch-22 by documenting energy savings derived from using synthetic lubricants with high film strength friction-reducing additive technology. Measuring energy savings provides a more immediate and definitive means of justifying the use of such performance-formulated lubricants. Because the cost of energy is a current operating expense, energy savings derived from the use of high-performance lubricants can immediately offset the increased purchase cost. And if the energy savings are sufficiently large, it eliminates having to justify the expenditure through maintenance cost reductions.
As energy costs continue to rise, the amount of energy used becomes a greater and more immediate concern to every company’s profitability. Energy cost, often the largest expense of operating rotating equipment, can exceed the cost of maintenance on rotating equipment by 20 to 25 times or more (Figure 1). Because the energy costs are so great, even a one percent reduction in energy consumption produces large dollar savings. This is why significant improvements in lubricant quality offer immensely leveraged opportunities to reduce costs and increase the company’s overall earnings.
Measuring Energy Savings
Energy savings are most easily measured by comparing the energy use of the electric motors that power the equipment prior to and following the equipment’s lubricant(s) upgrade. Improved equipment efficiency, which is a by-product of the upgraded lubricant, can result in increased machine output, lower operating temperatures and/or reduced energy use. Therefore, accurate comparisons require the equipment to operate at equal work loads when readings are taken. While it is not always possible to measure each variable, a sufficiently large sampling will provide reliable results.
Case Study #1 - Giant Refining Co.
Giant Refining Co. produces 20,000 barrels of oil per day in its New Mexico refinery. In 1997, senior maintenance planner Cecil Cunningham conducted an energy study on lubricants. He selected eight electrically driven process pumps to test the energy savings potential of replacing the R&O mineral oil currently used with a premium lubricant. Cunningham’s report concluded, “Based on our test data, using the synthetic lubricating oil Royal Purple in all lubricated equipment should provide an eight percent average reduction in electrical amperage, a savings of approximately $216,000 per year.” As a result of his testing, he was able to justify converting to the premium lubricant throughout the plant and the change has contributed significantly to Giant’s overall profitability.
Phase I of the test was conducted in two stages. The first stage was to obtain baseline data from the selected motors. The amperage on each motor was checked one day per week, twice on that day, for three months. This was to balance differences in unit operation changes. Stage two was to upgrade the oil using a normal flush out procedure. Amperage draw was checked daily for an additional three-month period (Table 1).
Case Study #2 - Major North American Tire Manufacturer
A reliability technician for a tire manufacturer in the southeastern United States tested the energy savings potential of premium lubricants in February 1999. The technician randomly selected 14 pieces of equipment in several plants for evaluation. An ISO VG 32 synthetic lubricant was tested in pumps, compressors and conveyors. The company reduced total energy usage in the test equipment by three percent with an estimated annual savings of $26,884.97. Significant reductions in operating temperature for much of the equipment were also achieved (Table 2).
The amperage, voltage and operating temperature of the equipment were measured before and after the oil change. The data was collected using voltage and amperage meters plus a handheld infrared digital thermometer. Measurement readings were taken prior to the oil change at sufficient frequency to ensure an accurate baseline had been established. Following the oil change, data was monitored for an entire year to make sure that the improvements in performance were permanent.
Case Study #3 - Various Ammonia Refrigeration Compressors
Over the past three years, energy savings in food processing plants were documented in reciprocating and flooded screw ammonia refrigeration compressors. The premium lubricant that was selected produced energy savings in ammonia refrigeration compressors in two ways: First, the lubricant reduces friction in the compressor. And second, it remains in the compressor and is not carried downstream with the ammonia into the cold side of the system where it can interfere with the cooling efficiency of the unit.
Table 3 provides a summary for the results on the 34 refrigeration compressors involved in this study. The high VI (Viscosity Index) synthetic lubricant produced significant energy savings regardless of compressor make, type and the previous oil replaced. The lubricant produced an average energy savings of 10.11 percent. In virtually every compressor, oil consumption due to carryover with the ammonia into the cold side of the system was either drastically reduced or eliminated.
Refrigeration specialist Bill Irvin collected data from various plant compressors before and after upgrading the oil to a new, high-performance lubricant. The duration of measurement varied based on the desires of each location. Typically, data was collected for one week before and after the oil change. To gather the information, Irvin installed a Pace Scientific XR440-M pocket logger with the appropriate sensors. This unit measured and recorded the suction pressure, discharge pressure and AC amperage of the compressors. Data was collected every two seconds, averaged every two minutes and was later downloaded into a PC laptop computer. Irvin eliminated periods of downtime and plotted the remaining data using 30-minute averages in Microsoft Excel. By comparing the before and after data on the compressors while operating at equal work loads, he was able to document the energy savings derived from the improvement in the efficiency of the compressors.
Due to the increasing cost and tightened availability of energy, the opportunity for significant savings in rotating equipment through improved lubrication is ever increasing. Energy cost is never a part of the maintenance budget, but a part of the operating budget. However, documenting energy savings resulting from improved lubrication creates the opportunity to reduce maintenance costs and increase equipment reliability and profitability. Though the potential for energy savings can vary greatly with different equipment, even a small percentage reduction in energy use will typically pay for the plant’s total lubricant expense within a few months.
Author’s Note: The names of the tire manufacturer and its reliability technician were withheld due to the company’s policy prohibiting the use of its name.