AS ISO 13381.1:2014 pdf free
AS ISO 13381.1:2014 pdf free.Condition monitoring and diagnostics of machines – Prognostics
Influence factors are parameters that effect the deterioration rate of a failure mode, such as temperature,viscosity, clearance, load and speed. Each influence factor may be considered to be a symptom of an existing failure mode and is represented in Figure 1 by the solid lines that connect existing failure mode trends.
Influence factors also have effects on the progression and initiation of other either existing or future faults (see Figure 2).
An example of a situation as described by Figure 2 is where the initial parameter of vibration, due to a fault in a lubricating oil pump bearing (primary failure mode), influences the initiation of a seal failure (secondary failure mode) which has a faster deterioration rate than the bearing. As this seal progresses to failure, the leakage results in a loss of oil delivery pressure, which influences the initiation of an impeller failure in the pump (tertiary failure mode), which has a slower deterioration rate.
The failure definition set point for a parameter/descriptor is the final value that it reaches at the point in time when the item fails. This value is normally determined historically from failure history.
The trip set point, however, is the parameter/descriptor value at which the machine is shut down and is normally less than its failure set point. This value is normally determined from standards, manufacturers’ guidelines and experience. This is the value normally used to define the failed condition. However, this value does not usually reflect the fully failed condition, due to its lower set point required to prevent consequential damage or catastrophic failure.
Alert and alarm limits are normally set at a value less than the trip set point. This value is usually based on the maintenance lead time required. However, the following parameters should be known before deciding such alert values:
a) the confidence level of the prognosis;
b) future production requirements;AS ISO 13381.1 pdf free download.
