Quality assurance and quality control in oil analysis do not begin and end in the laboratory. Quality assurance programs generally audit only the laboratory process for accurate, repeatable test results. Without the proper controls in place prior to analysis, testing may be performed on non-representative, mislabeled, or out-dated samples resulting in improper corrective actions and added costs to the oil analysis program. Also, if corrective action is not taken in a timely manner, machine failures or increased damage can occur.

Controls that may be overlooked prior to the sample arriving at the laboratory or after the analysis is performed include:

• Storing new oil
• Testing new oil
• Labeling the sample
• Sampling technique
• Using applicable test methods
• Timely sampling, analysis, and corrective action.

Quality assurance and control begin before the oil is added to the machine’s reservoir. Variables that could affect data integrity must be regulated.

Ensuring that the correct lubricant has been obtained from the oil vendor and that the lubricant container has been handled properly prevent problems from being introduced into the reservoir.

New lubrication containers must easily identify the lubricant type and grade. Storing the container in a clean, dry place will aid in ensuring that the lubricant is not contaminated with debris or water.

Also, the container should be kept in a controlled atmosphere to protect it from excessive heat or cold.

Remember that it is possible to receive mislabeled or contaminated lubricant from the oil vendor. Periodically, new lubrication samples should be analyzed by the laboratory as part of the quality assurance program.

Transferring lubricant from a storage container to the reservoir also can introduce contamination. If the product is not being dispensed directly from its original container, it is important to use a clean, dry receptacle for moving the lubricant to its point of use. Each container or device used for dispensing the lubricant should be clearly marked and used exclusively for one product.

When obtaining a sample from the machine reservoir for testing, use a technique that will provide a representative sample. The sampling procedure must ensure that the technique used is consistent each time a sample is drawn to send to the laboratory. This will guarantee that tracking and trending values received from the laboratory are consistent and representative over time.

With any oil analysis program, it is important that the sample is drawn at the same location every time as variations in the oil can sometimes be seen at different locations in the reservoir. Always check the oil level to be sure there is sufficient oil in the reservoir to obtain a sample.

Whenever possible, the sample should be drawn while the unit is operating. If that is not possible, the sample should be drawn as soon after shutdown as possible. This assures that separation of any particles or water in the reservoir does not occur.

Valves can also be installed for sampling purposes. The valve should be installed upstream of the filter so problems such as wear in the unit can be identified. Periodically taking a sample after the filter also can be useful. This gives a good indication of how well the filter is working.

When sampling a unit with a valve, make sure the valve has been cleaned and thoroughly flushed before collecting the sample. When sampling a unit that does not have a valve, use a siphoning pump and tubing. It is critical that all sampling equipment be clean and dry.

When using tubing, cut the length so the sample will be drawn from the midpoint of the reservoir. Each piece of tubing should be used only once and then discarded. Extreme caution must be exercised when using tubing to obtain oil samples from units which are operating. The tubing can be caught by moving parts and pulled into the unit, resulting in damage. Many units will have to be shut down before sampling.

The most undesirable method for obtaining a sample is through a drain plug. If this procedure must be used, an adequate amount of oil should be drained first so that particles, debris, and water from the bottom of the reservoir are removed before collecting a sample.

Be cautious of the results obtained from a sample that has been drawn through a drain plug. Most likely they will not be representative of the reservoir.

All samples should be collected in clean, dry bottles that have never been used. Depending on the type of analysis, bottles can be purchased that have been certified to meet specific cleanliness levels. Labels should be placed on sample bottles immediately after sampling to prevent confusion.

Label information should include but not be limited to reservoir identification, date of sample, lubricant hours ( if applicable), and run time hours (if applicable).

For tracking and trending purposes, the same reservoir identification should be supplied to the laboratory each time a sample is drawn from that reservoir.

Once a sample has been drawn, it is important to have it delivered to the laboratory in a timely manner. It is equally important that the laboratory give results in a timely manner.

When selecting a laboratory for oil analysis, look for attributes such as quality assurance, turn around time, testing capabilities, and good customer service. A quality laboratory will have an in-house quality assurance program, for example the 10-CFR-50 Appendix B quality assurance and control program, or an ISO certification. A laboratory with good quality assurance should provide accurate, dependable results on every  report it provides.

Tour the laboratory if possible. Ask to receive copies of audits or actually audit its quality assurance program. An open line of communication is important. The laboratory will benefit from as much information about equipment, lubrication types, environmental conditions, and maintenance practices as can be provided. In return, the laboratory should be able to provide an in-depth interpretation and recommend action in the oil analysis report.

Once a report has been received from the laboratory, it is important to act quickly on any recommendations or findings. Over time, increased productivity, extended machine life, decreased downtime, and decreased maintenance costs will be noted.

Choose a sampling frequency and an analysis package suitable for the different types of machinery in the plant. For example, engine samples should be tested for coolant and fuel contamination which is not applicable to other systems such as hydraulic equipment. Critical equipment may be sampled on a more frequent basis and include a more extensive analysis.

A close review of the current oil analysis program can ensure the best value for the company’s investment. The program should not only audit the laboratory practices but also verify lubrication storage, lubrication sampling, sample handling, testing methods application, and responsiveness to the analysis results. Monitoring the entire program will make quality control more efficient and effective.

as seen in:
Maintenance Technology
November, 1997