Add visual management to your lube-program toolbox through an array of color-coded solutions.
By Ken Bannister, MEch Eng (UK), CMRP, MLE, Contributing Editor
When you hear the word lubrication, what color comes to mind? If you answer brown, or allude to some shade of it, you’re in good company. More than 80% of maintainers to whom I’ve posed this question over the past 30 years have responded the same way.
The reality is that oil and grease products come in a rainbow of colors and shades, including white, gray, black, silver, blue, green, red, purple, and every variation of brown, from golden honey to dark, earth tones. Manufacturers typically color these products for their own purposes. Unfortunately, there’s no formal industry standard or convention regarding their choices, with the exception that most food-grade greases tend to be white.
Most lubricant colors are naturally influenced by the color of the crude base-oil stock and its additive package. For example, when molybdenum disulphide (MoS2) is added in any quantity, it can significantly darken the lubricant to near black in color. Manufacturers, though, add colorants to their respective lubricants to help identify different brands and/or make products more appealing and marketable to the end user.
Despite incongruent colorization, maintenance departments can take advantage of differences in lubricant colors in their plants. For example, if two or more grease brands or different colors are employed in a facility, personnel can be made aware of which color belongs to what bearing by a photo of that grease color posted on the machine or close to the grease nipple. If a trace amount of the previously used grease is evident at the bearing or grease nipple, maintainers would (should be made to) understand that they are not to pump a grease of a different color or shade on top of the original grease.
Oil colors are a different matter. Oil ages in service and its additive package will deplete through contamination, heat, and oxidation. This causes a natural darkening in color. That visual cue has been used for many years in industry and the automotive world to manage oil changes. Sadly, this somewhat risky strategy can fall flat when an oil is changed out with one of a different color and additive composition—especially in the case of darker oils.
Introducing color coding
In 1950, the prestigious UK Scientific Lubrication Journal published an article by M.J. Harrison titled “Color Codes.” In it, Harrison, who at the time was an engineer in the technical department of the UK’s C.C. Wakefield & Co. (now known as Castrol), detailed a symbol/color-control system methodology for identifying the lubricants used in an industrial plant. As he pointed out, employing symbols to denote frequency of application and colors to signify lubricant type would ensure that unskilled workers were able to perform “factory lubrication” in a consistent manner, with scientific precision.
Harrison went on to recommend the use of different 1-in.-high geometric symbols painted on lubricant reservoirs or at lube points to represent lubrication-interval schedules. He proposed a circle to represent the need for daily lubrication, a triangle for weekly lubrication, and a square to represent monthly intervals between lubrication activities. For activities conducted on a quarterly basis (or over longer periods), the square was to again be used, but this time with a number painted inside the square to highlight the number of interval months.
To determine the correct lubricant to apply, each symbol was to be painted one of three primary colors: yellow, red, or blue to correspond with an already-determined lubricant legend. If more than three lubricants were to be used, the same colors were used again, but with the addition of a bold black diagonal stripe across the symbol.
But Harrison didn’t stop with the design and color of symbols and shapes to help identify different lubricant and application intervals in a facility. He also advocated color-coding reservoirs and dedicated transfer equipment to eliminate cross-contamination problems.
Which colors to use
Color identification is an ideal means of ensuring that the right lubricant ends up in the right place, at the right time. The actual colors themselves are not as important as their consistent use, i.e., assigning a specific color to a single lubricant and all dedicated equipment employed in its use, storage, and transfer within the plant environment, as depicted in Fig. 1.
Harrison initially promoted the three primary colors of red, blue, and yellow for his system. In modern plant environments, however, we’re comfortable using primary and secondary color palettes, including green, orange, and purple. This is clearly evidenced by the breadth of today’s commercially available, color-coded lubrication-handling systems, including the example transfer products shown in Figs. 2 and 3.
Lubricant storage and transfer systems, though, reflect just one area where colorization pays off for a site. Another important use of color identification involves a condition-based approach to filling oil reservoirs.
Figure 4 is a good example of this Hi-Lo technique. It involves using red, amber (yellow), and green lines taped on the side of an automated-lubrication-system reservoir. This arrangement is known as a RAG (red/amber/green), or the traffic-light indicator system:
- The green line indicates the upper fill level.
- The amber (yellow) line indicates a level at which the operator is to contact the maintenance department with a first request to fill the reservoir.
- The red line alerts the operator to call in a priority request to fill the reservoir.
Coloring your efforts
Today, you’ll find an array of color-coded tags and transfer equipment in the marketplace. These types of innovative solutions are relatively inexpensive to purchase and implement—and highly effective when used consistently. The question is, “Just how colorful are your lubrication efforts?” MT
Ken Bannister is managing partner and principal consultant for EngTech Industries Inc., (Innerkip, Ontario, Canada), an asset management-consulting firm now specializing in the implementation of certifiable ISO 55001 lubrication-management programs and asset-management systems. For further details, telephone (519) 469-9173, or email firstname.lastname@example.org.