ADASH Ltd.
Adash 4900 – Vibrio M
Further technical and contact information can be found at www.adash.com
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Velocity measurement amplitude response
Measurement accuracy for RMS vibration velocity (0,1 – 100 mm/s range) on 80 Hz reference
frequency is +/- 2,5 %
Acceleration measurement amplitude response
Measurement accuracy for RMS vibration acceleration (0,1 – 10 g range) on 8kHz reference
frequency is +/- 2,5 %
Sensor sensitivity
Before any calibration you need to know, what exact sensitivity of sensor is set in the instrument. See
the switch off screen, which contains this information. Keep the button pushed and read the
information.
Description of numbers on switch off screen:
1. Firmware version
2. Serial number
3. HP filter frequency for bearing (0,5 kHz), HP filter frequency for ISO (10 Hz)
4. The sensor sensitivity (100 mV/g)
The sensitivity of sensor is usually in 95-105 mV/g range.
Basic test with A4801 Sensor Simulator
If you have the A4801 unit, you can regularly test the unit on two frequencies 80Hz and 8kHz. On the
initial A4900 screen are displayed RMS values of velocity and acceleration. The velocity value should
be 10 mm/s and the acceleration should be 0.5g.
The signal from A4801 is adjusted for exact 100mV/g sensitivity. When the sensitivity of A4900 unit is
e.g. 95mV/g, then the higher values (10.5mm/s and 0.53g) will be displayed. Expected values from the
A4801 should be multiplied by 100/95 coefficient.
Basic test with sensor and shaker
The procedure should be the same as with A4801. Set on the shaker 10mm/s on 80Hz and check the
RMS velocity value on the initial screen. Then set 0.5g on 1.2 kHz or higher and check the RMS
acceleration. Bellow 1.2 kHz the HP filtering is applied and the result would be distorted.
Advanced tests of velocity measurement
Use the shaker and sensor. You can make the frequency response and the amplitude response.
Use the amplitude 10mm/s for frequency response test. Change the frequency from 6 to 1200 Hz and
draw the curve. This is the exact response with the sensor.
Set the 80Hz for amplitude response. Change the amplitude from 0.1 to 100 mm/s and read values.
