Certified Maintenance & Reliability Professional (CMRP) Practice Exam 2025 – All-in-One Guide to Master Your Certification!

The correct answer is based on the ISO cleanliness standards for oil, which utilize a three-number code to indicate the levels of particles present in the oil. Each of the three numbers corresponds to a specific range of particle counts measured in sizes: over 4 microns, over 6 microns, and over 14 microns.

For the sample marked 16/14/11, the first number (16) indicates the count of particles larger than 4 microns, the second number (14) is for particles larger than 6 microns, and the last number (11) refers to particles larger than 14 microns. The lower these numbers, the cleaner the oil is considered to be.

In comparison, the sample marked 22/21/17 has higher values across all particle size ranges which indicates a greater number of particles present in the oil. This suggests that this sample is significantly more contaminated than the other one.

Thus, the sample 16/14/11 represents cleaner oil because it has lower particle counts in each measured size category, making it more suitable for machinery requiring clean oil for optimal operation and reliability.