Condition monitoring of machines is a maintenance technique. It is a set of actions to keep the equipment, services, and buildings in good operating condition. It is a proactive maintenance practice. It is practiced to keep the equipment and services running smoothly and efficiently, without failure. Condition monitoring is on line maintenance of equipment. Monitoring of equipment condition is started since the man has invented the wheel. He had started to lubricate the wheel hub to run it smoothly and efficiently. This has reduced the failure of the wheel and also reduced the frequency of failure of the wheel.
Condition monitoring of machines a concept developed for preventive maintenance. In the preventive maintenance concept, equipment is continuously monitored for its smooth and trouble-free running. The parameters like bearing heat, vibration, lubricant level, contamination in the lubricant, and noise in the equipment are observed. If these parameters are found in an abnormal range, then corrective actions are taken to prevent them. Thus the chances of premature failure of the equipment are reduced. With this technique the useful life of the equipment is prolonged.
In the maintenance functions following activities are being carried out:
(1) Inspection, lubrication, repair, and replacement of a deteriorated component of the plant equipment.
(2) Repairing and painting of the existing building and its structure.
(3) Generation, supply, and operation of utilities like water, air, steam, and electricity to plants and buildings.
(4) Replacement of existing equipment and building.
(5) Installation of new equipment and constructions.
(6) Storing of equipment for maintenance.
(7) Maintenance of fire protection equipment.
(8) Waste disposal from plants and buildings.
(9) Pollution and noise control in plants and buildings
(10) To do good housekeeping in plants and buildings.
CONDITION MONITORING SYSTEM
Maintenance systems are classified into three main categories.
(1) Breakdown Maintenance
(3) Predictive Maintenance
Maintenance of the equipment is undertaken when it breaks down. It does not perform the intended function. This type of equipment maintenance is the unplanned one. It is to be attended to suddenly and urgently. If there is single line equipment in the plant, this causes downtime and heavy production loss. This type of maintenance is good for the plants, where two-line equipment is available. Second-line equipment is taken in line, before repairing of down equipment. This provides sufficient time for maintenance staff to carry out repairs.
Equipment conditions are monitored continuously for good health. If any abnormality is found in its operating parameters, then corrective action is taken to avoid the breakdown of the equipment. This is carried out through a systematic approach of periodic inspection of equipment. This helps to get the equipment attended prior to its failure or breakdown. Preventive maintenance has the following advantages:
(1) It increases the availability of plants for production.
(2) Better planning for maintenance work and provide sufficient time for procurement of spare parts.
(3) Reduces time for breakdown repair.
(4) To reduce excessive downtime, to save repairing cost, To avoid production loss.
The predictive maintenance technique collects quantitative measurement data on the deterioration of equipment components. The data is collected for wear, tear, corrosion, erosion, vibration, the temperature of bearing, etc. This data of the equipment condition is collected and recorded online with the help of sensors mounted on equipment. This data is studied and analyzed by maintenance experts. They predicted equipment repair and replacement. Based on the predicament, equipment repair and replacement is planned in advance. There are two distinct fields in predictive maintenance:
(1) Vibration measurements in rotating machines like compressors, turbines, fans, and blowers.
(2) Thickness measurement in pipes and vessels. Deterioration in thickness occurs due to corrosion and erosion.
PREDICTIVE MAINTENANCE INSTRUMENTS:
(1) Vibration and Frequency Analyzer ( Used to detect imbalance and misalignment in rotating machines.)
(2) Radiography and Ultrasonic devices. (To measure temperature and thickness)
(3) Dye penetrants ( To locate cracks in metals)
(4) Noise measuring instruments. ( To find looseness of parts)
(5) Temperature sensing instruments. ( To inspect bearing condition)