Section 20
00-02-0841
2013-01-14
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13 -
Setting of Alarms
The alarm values may vary considerably, up or down, for different machines. The values
chosen will normally be set relative to a baseline value determined from experience for the
measurement position or direction for that particular machine.
As shown in Figure 7, it is recommended that the alarm value be set higher than the baseline
by an amount equal to 25% of the upper limit for Zone B. If the baseline is low, the alarm
should be below Zone C.
Where there is no established baseline (for example with a new machine) the initial alarm
setting should be based either on experience with other similar machines or relative to agreed
acceptance values.
After a period of time, the steady-state baseline value will be established and the alarm setting
should be adjusted accordingly.
Recommended Alarm Settings
The following are guidelines based on industry standards. Actual settings will vary depending
on mounting and unit installation. (Note: Refer to the Appendix for recommended settings by
specific manufacturers.) Experience with a given installation should be the major factor in
deciding the settings.
It is recommended that the alarm value should not normally exceed 1.25 times the upper limit
of zone B.