Why you need Continuous Calibration

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by Brian Graney,

Single point calibration is not a calibration at all. It is a sensitivity check at 100 Hz. An accelerometer is a dynamic sensor therefore it is required to have its sensitivity checked over its entire frequency range. There are two basic methods for doing this.

1) Point to point step calibration, the sensitivity is checked at selected frequencies and a calibration curve is drawn out.

2) Is called continuous method also known as Full Frequency Sweep or B&K White Noise Method, as implied sensitivity is checked over the full frequency range of the sensor. This is about a 15 minute procedure and a full frequency graph is printed with the calibration certificate.

Below the single calibration only checks the sensitivity at one (1) frequency 100 Hz. The green arrows represent the optimal range of the accelerometer. That is the frequency range you are suppose to take your vibration measurements. If you do not check the sensitivity over the full range of the accelerometer you do not know if it is performing to specification. That is why you should always request a continuous calibration certificate when you buy an accelerometer.

Comments (2)

• I would like to know how to read vibrations to determine, whether it is a bearing, pump impeller, etc.

  1) Posted 8:08 am, 25 March 2009 by jim

• We are taking weekly vibration checks on different equipments in our plant. What is the best setting for the sensitivity of the sensor. Does it depend on tne equipment or different equipment can have the same sensitivity settings for the sensor.

  2) Posted 3:27 pm, 07 May 2009 by Edward Akukwe

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