The API Standard 614 / ISO 10438-2 states the following for new equipment cleanliness:
After 1 hour of an oil flush yielding clean screen. To further verify cleanliness, the system shall be visually inspected at two to six points selected by the inspector. The system shall be considered clean when foreign matter, such as scale, rust, metal shavings and sand, are not visible to the eye and grittiness is not detectable to the touch. The ANSI/AGMA 9005-E02 states the following for new oil cleanliness; must be free of visible suspended or settled contaminants at the time it is installed for use.
Often new oil can be 8 to 16 times more contaminated than OEM recommended cleanliness levels for operating fluid. But what is clean enough? It is a well-documented statement that the critical particle size that must be controlled is typically 1 to 5 microns to maximize component life and that controlling the abrasive contaminants in the range of 2 to 22-micron range in a lubricant is necessary for reducing wear.
A simple improvement in fluid cleanliness can make a large difference. A study cited in by Nissan Motors of Japan attributed 85% of hydraulic equipment failures due to contamination. By utilizing better filtration, failures were reduced by nearly 90% in the factories. This improvement resulted in tens of thousands of dollars in recognized savings as well as increased productivity. It is argued that the improvement paved the way for Nissan to become a major force in the automobile market. Several engine manufacturers have published studies attributing the control of lubricant contamination in engines will provide an astounding 500+% internal rate of return. Contamination is often considered to be an issue with in-service fluids, but storage of lubricants has a significant influence on the introduction of contamination as well.
- Delivery: Determine an acceptable and manageable cleanliness level for stored fluids. Begin with understanding the cleanliness of oils being delivered on site using oil analysis. Particle count, water concentration, and even elemental metals will provide information to determine if there has be a breach in cleanliness delivery. New oils typically average an ISO 4406 code of 20/19/16 cleanliness or higher which is up to eight times dirtier than recommended for most of the critical machinery. Some suppliers offer filtration of new oils prior to delivery. This is a best practice that should be strongly considered.
- Storage: Take measures to exclude contaminants from becoming part of the lubricant or fluid. This must happen in the main storage area as well as the individual storage stations throughout your plant. Drums that are not yet opened for dispensing should be stored in a manner that prevents contamination. A best practice is to store them in a temperature control room, stacked on a rack (if not delivered in bulk) in a horizontal position with the bung holes in a 3 and 9 o’clock position. This will provide a seal preventing ingress of contaminants. If the drume are to be stored outside, make sure it is in a covered space and that if the drums can only be kept vertically with covered tops or tilted so that the top does not allow standing water to seep in through the bung holes.
- Oil Room Design: a contributing factor for oil room design includes location, fire safety, workers safety, ergonomics, mixing control, contamination ingress control, procedures for bringing new oil into service, the ability to document actions (record keeping), and labels that are visible and legible. Recording delivery dates and turning inventory according to ‘First-In-First-Out (FIFO)’ policy is essential.
- Handling: Preserving the integrity of the fluid while getting it from storage to usage reducing contamination. Bear in mind that often the best ways are also the easiest as well as the most efficient. Some best practices include:
- Filtered hand pumps with air breathers
- Transfer pumps with quick-connects
- Top up/small oil change out containers
- Containers that reduce the potential of contamination
Funnels represent the highest risk factor for contamination ingress while adding oil into components. Consider retrofitting containers with air breathers, and hand pumps with quick disconnect couplers. Companies that establish a procedure that incorporates adding oil via a portable filtration system have reduced contamination.
- Exclusion: The cost of cleaning dirty oil can be 10X higher than keeping it clean in the first place. An economic and easy way to help avoid contamination is to incorporate exclusion principles. Breathers on the sumps can exclude particles as small as ½ micron. Many breathers are rated at 20 CFM of air or an equivalent of 150 GPM change in tank fluid level. Desiccant breathers will also exclude moisture. These change color according to moisture absorption. Protecting new oil from contamination is possible if purchased in larger containers or bulk, per usage. Identifying and repairing leaks reduces the ingress of contamination. If oil can leak out of a system, it is very possible that contamination can enter the same system. As oil heats up during operation it will expand, but upon cooling iy will contract. This may set up a situation that draws contamination into a leak. Contamination is often the deciding factor for an oil drain, kidney loop filtration will aid extending drains, or time based changes can be monitored via oil analysis to determine when the oil should be changed.
- Review lubricant storage and handling: It is a common misconception that new oil is clean. Typically, new oil is 8 to 16 times dirtier than recommended for hydraulics and other critical components and must always be filtered prior to use. Best practice includes a review of the lubricant storage and handling practices. Once the oil is clean, it must stay clean. Many lubrication reservoirs have inadequate breathers which offer little or no protection against moisture or particle ingression, the two most significant causes of mechanical failure. An audit of the system is also been used and proved to be a best practice.
- Continuous training: Often companies will train new employees but assume others have learned all they need to know. Nothing could be further from the truth. Companies that actively engage in a program of continuous competency development of shown monumental gains in productive and cost avoidance.
Michael D. Holloway, MLE, CRL, LLA I & II, MLT I & II, MLA I-III, OMA 1, CLS
Principle Consultant, Certified Reliability Leader