Maintenance procedures can be classified in three basic categories:
Corrective Maintenance is known as reactive maintenance. In other words, waiting for something to break down before worrying about repairing or replacing it. While this process may require less expense in manpower, it can contribute to longer than normal downtime while waiting on replacement parts or equipment to arrive, or a need to have an extensive inventory of those replacement parts or equipment on hand.
Preventive Maintenance is also referred to as scheduled maintenance. This form of maintenance is based on a time based understanding of when breakdown occurs, when specific preventive measures are not taken. Preventive maintenance focuses on replacing or repairing worn or expended system parts before failure occurs, extending the life of mechanical systems. Common scheduled maintenance tasks include changing filters and lubricants, cleaning and flushing of contaminants, correcting tolerance discrepancies, and other items that keep machinery and buildings operating at their peak efficiency.
Predictive Maintenance relies on regular analysis of data collected from in-service system equipment and components to determine when maintenance will be required or a time when failure will occur. Predictive maintenance procedures often include computerized maintenance management systems (CMMS) to gather information from data loggers or sensors which are placed on equipment to track temperature, humidity, speed, pressure, voltage, amperage, flow rates, occupancy, and a multitude of other factors related to the performance of a piece of equipment or building system. When a data logger records a measurement that is outside of a set parameter, the computer sends an alarm that can be programmed to perform many functions to include but not limited to: create a work order, send out digital information to maintenance staff via text or email, and shut down equipment to prevent catastrophic failure.
Although initial setup of CCMS systems can be quite costly, over time this form of maintenance can result in significant savings from not having to keep a large inventory of replacement parts on hand, efficient scheduling of people and ordering of parts, and less unplanned failure of equipment. CCMS systems are commonly found in commercial buildings such as hospitals, office and institutional buildings, and resorts.