SPM BC100 - Measuring Range

14
The measuring range of the Bearing Checker is large and
covers most bearing applications, but there are a few cases
where shock pulse monitoring should only be attempted with
installed measuring equipment, or not at all.
High speed bearings: The Bearing Checker accepts max.
19 999 rpm, 1 999 mm shaft diameter, and a dBi of 40. The
upper part of the table contains examples of possible com-
binations of shaft diameter and rpm giving a maximum dBi
of 40. The lower part of the table examplifies combinations
that give dBi = 0. The instrument calculates the dBi up to 40.
However, it is possible to manually set the dBi to max. 60. A
reason for setting dbi > 40 is when measuring on e.g. turbo
chargers, high speed gear boxes etc.
Low speed bearings: The lowest acceptable dBi is -9 dB.
However, it is nearly impossible to get a meaningful read-
ing from bearings in the extremely low speed ranges. The
practical limit are bearings with a dBi around 0 dB (see lower
half of the table).
A heavy load with a well defined direction and a low inter-
ference level make it easier to get readings from low speed
bearings. Successful SPM monitoring has been carried out
on bearings with dBi = –3 (54 rpm, shaft diameter 260 mm).
Note that the dynamic measuring range decreases when dBi
values get below 0. For example, a bearing with dBi = –3
showed very heavy damages at dBn = 40.
Installed adapters required: The installation of adapters is
strongly recommended for all systematic shock pulse moni-
toring. In some cases it is a requirement:
• on bearings with dBi below 5
• on heavily vibrating bearing housings
• on covered bearing housings.
Low speed: Do not use a handheld probe on low speed
bearings. As a rule, the measurement should cover at least
10 full revolutions of the shaft. A single damaged part in the
raceway will cause a strong pulse only when hit by a rolling
element while passing through the load zone. It can take
several revolutions before that event occurs or is repeated.
Adapters required!
Covered
housing
dBi < 5
Heavy vibration
Shaft, mm rpm dBi
50 19 999 40
100 13 000 40
180 10 000 40
300 6 000 40
500 5 000 40
1 000 3 400 40
1 999 2 200 40
1 999 24 0
1 000 35 0
650 45 0
500 52 0
300 72 0
180 100 0
100 140 0
50 210 0
Measuring range