When the individual pieces of equipment have been identified for preventive maintenance, there must be a procedure for identifying the order in which they are to be done. Not everything can be done first. First In–First Out (FIFO) is one
way of scheduling demand. Using FIFO means that the next preventive task picked off the work request list, or the next card pulled from the file, is the next preventive maintenance work order. The problem with this ‘‘first come, first served’’ method is that the more desirable work in friendly locations tends to get done while other equipment somehow never gets its preventive maintenance. The improved method is

Priority = Need Urgency X Customer Rank X Equipment Criticality.

The acronym NUCREC will help in remembering the crucial factors. NUCREC improves on the Ranking Index for Maintenance Expenditures (RIME) in several ways:
1. The customer rank is added.
2. The most important item is given the number-one rating.
3. The number of ratings in the scale may be varied according to the needs of the particular organization.
4. Part essentiality may be considered.

A rating system of numbers 1 through 4 is recommended. Since most humans think of number 1 as the first priority to get done, the NUCREC system does number 1 first.

Need urgency ratings include
1. Emergency; safety hazard with potential further damage if not corrected immediately; call back for unsatisfactory prior work
2. Downtime; facility or equipment is not producing revenue
3. Routine and preventive maintenance
4. As convenient, cosmetic.