Instrument Planned Maintenance

Today’s modern instruments are incredibly sophisticated and accurate. Yet, even with inbuilt computer based systems the instrument planned maintenance should never be overlooked.

The objective of this article is too service each component of a system according to its needs, general physical state, and that operational efficiency is maintained. The system as a whole should in theory, never break down. The exceptions of course are incidents outside normal operational conditions, for example - lightning strikes, flooding, and or mechanical damage, or the system or components are approaching their end of operational life span.

Determination of the frequency and level of planned maintenance is based on several factors.

These are:

• the known track records of the device in normal conditions
• the severity of ambient conditions
• the severity of the service
• special problems concomitant with the service such as:
  • periodic blockages
  • seal failures
  • vibration issues
  • immersion.
    
    An instrument which is housed in a weather proof enclosure, on a non-aggressive surface which has a good reliability record, will need a calibration check every 3 months to at the very least, once a year. The same instrument in a severe environment on an aggressive surface could require a weekly service, monthly calibration and in general have a complete overhaul every six months.
    Further factors to be taken into account include the operational importance of the instrument, the ease of access to the instrument and the operational implications of downtime of the instrument. An important overhauling factor is the financial feasibility.  If it cost more to repair than what a new unit is worth, it would pay to scrap the old one for spares and buy a new one.
    
    Having determined all the required information, a schedule can then be constructed, after listing all the relevant data.
     Typical data to be gathered:

1.    list all components to be scheduled for maintenance

2.    determine the period between servicing and the level of servicing for each

3.    if there are instruments which can be used in multiple locations, note the type range and configuration for each installation

4.    list spares needed for each level of servicing and any equipment required. Note: the equipment required for servicing should be deemed a workshop standard and have a higher accuracy that the instrument being serviced.

5.    for each component, note any difficulties in getting access

6.    assemble the instruments into areas or groups for convenience.

 Mal Garrick