It’s a nagging, industry-wide question, and one that keeps many a supplier and end user up at night.
In the multi-step process of moving lubricants from THEIR tanks to YOUR equipment, where does contamination start? At what point do dirt and/or moisture enter the supply chain? Is it a problem with storage, handling, dispensing or a combination? This three-part series aims to answer these questions once and for all. Based on studies of actual field data of the cleanliness of new oil put into equipment, it will provide recommendations on how to more effectively guarantee cleanliness in the future. A continuing theme in this series will be the fact that it takes a strong, cooperative effort among lubricant supplier, distributor/marketer and end user for any oil cleanliness program to be successful (see Fig. 1).
Most lubricants purchased today come from a distributor and are delivered in the following ways:
How the lubricant is delivered by the distributor will have a major impact on oil cleanliness.
The lubricant blender also plays a key role in oil cleanliness. Typically, turbine and hydraulic oils are sent out of the blend plant at a cleanliness of 19/17/14. Once it is put in trucks or drums, the delivered oil will not be as clean. (One major manufacturer that is filtering hydraulic oil and putting it in new sealed steel drums, however, is achieving a cleanliness rating of 14/11/9. There is a cost for this procedure, but customers know they will receive very clean hydraulic oil as a result of it.)
Some companies may require special handling of their oils. A case in point is General Electric, which has a minimum cleanliness rating for turbine oils of 16/13. This is achieved by delivering filtered turbine oil to GE in a dedicated bulk truck. Lubricant suppliers are providing this service either directly from the blend plant or through filtration at the distributor.
The end user also has a responsibility to maintain oil cleanliness. Oil can become dirty very quickly if it is not handled or dispensed properly. The customer needs to cooperate closely with the lube blender and distributor to develop a program achieving targeted oil cleanliness levels economically. Scope of this study In our study, new lubricants are being evaluated for two major contaminants: particles and water. All laboratory test work is being conducted by MRT Laboratories, an ISO 17025-2005 certified laboratory in Houston, TX. The following tests are being performed:
The following samples were purchased from four major lubricant manufacturers for evaluation:
As shown in Fig. 2, the lubricant flow through a distributor operation is being examined for both water and particle contamination. The major focus will be on turbine and hydraulic oils. Fluid cleanliness will be examined at each stage to determine the effect of storage and handling on contamination.
The final phase of the study will be focusing on end user handling of lubricants. Very clean fluid can be delivered to the plant, but without proper handling all efforts for clean oil are wasted.
Lubricants at several end-use facilities will be examined to determine the introduction of contaminants at the various stages of lubricant dispensing (as indicated by Fig. 3). The use of filters and filter carts in the achieving of fluid cleanliness targets also will be examined.
After all study data is collected, recommendations will be made on the optimum way to achieve fluid cleanliness in the most economical way. Subsequent installments in this series will address best practices for lubricant blenders, distributors and end users.
ISO 4406: 1999 Cleanliness Code
Cleanliness will be measured by the use of an optical laser counter that measures the number and size of various particles. Although this procedure was discussed thoroughly in a previous article on oil cleanliness (see pgs. 34-35, Lubrication Management & Technology, September/October 2007), it will be reviewed here.
The data in Table I are used to assign a cleanliness code number for a fluid:
The particle sizes measured are= 4 micron, = 6 micron and = 14 micron. The number of particles are measured with a particle counter and recorded by size per milliliter of fluid. Take, for example, a fluid with the following particle count:
= 4 micron = 8500/ml
= 6 micron = 1650/ml
= 14 micron = 300/ml
The shorthand notation according to ISO 4406:1999 would be 20/18/15 for this fluid. A lower number represents a cleaner fluid. Note, too, that a one-number increase in the cleanliness code represents a doubling in the number of particles. The other articles in this three-part series will utilize this code to represent fluid cleanliness.
Oil cleanliness is a very timely topic. Many end users today are demanding cleaner oil without understanding the costs involved. The next articles will address the issue of the cleanliness of oil currently supplied and best practices to assure that the oil will be clean when put into the equipment. The relationship between the lubricant supplier, distributor and end user needs to be cooperative and not adversarial. They all need to work with one another to assure clean oil at an economical cost.
Realistic cleanliness goals need to be established by equipment type before any program is implemented. A total program needs to be established, including the use of proper filtration when the fluid is in the equipment. This filtration also has been discussed in a previous article (pgs. 8-12, Lubrication Management & Technology, November/December 2007). Like everything else, effective filtration requires a strong cooperative effort between the end user and the filter manufacturer.
The second installment in this series will appear in the July/August issue of Lubrication Management & Technology.