AS ISO 5349.2:2013 Mechanical vibration—Measurement and evaluation of human exposure to hand-transmitted vibration
6.1.2.2 Vibration magnitude
Hand-held machines can produce high vibration magnitudes. A pneumatic hammer, for example, may generate a maximum acceleration of 20000 m/s² to 50000 m/s². However, much of this energy is at frequencies well outside the frequency range used in this part of ISO 5349. The accelerometer chosen for the measurement has therefore to be able to operate at these very high vibration magnitudes and yet still respond to the much lower magnitudes in the frequency range from 6,3 Hz to 1 250 Hz (one-third-octave band mid-frequencies). For the use of mechanical filters to suppress vibration at very high frequencies, see annex C.
6.1.2.3 Frequency range
Accelerometer selection will also be influenced by the fundamental resonance frequency of the accelerometer, this is a characteristic of the accelerometer (it is sometimes referred to as the “mounted resonance frequency”, “natural frequency” or “resonance frequency”). Information on the fundamental resonance frequency will be available from the accelerometer manufacturer. ISO 5348 recommends that the fundamental resonance frequency should be more than five times the maximum frequency of interest (for hand-transmitted vibration, this corresponds to 6250 Hz). For piezoelectric accelerometers, the fundamental resonance frequency should normally be much higher, ideally greater than 30 kHz, to minimize the likelihood of DC-shift distortion (see 6.2.4).
NOTE The fundamental resonance frequency of the accelerometer should not be confused with the resonance frequency of the accelerometer when mounted on a hand-held workpiece or power tool which is a characteristic of the whole accelerometer mounting system. In practice, the resonance of the mounted accelerometer on a hand-held workpiece or power tool will be substantially lower than the fundamental resonance frequency (see 6.1.4).
6.1.3 Location of accelerometers
Vibration measurements in accordance with ISO 5349-1 should be made at or near the surface of the hand (or hands) where the vibration enters the body. Preferably, the accelerometer should be located at the middle of the gripping zone (e.g. halfway along the width of the hand when gripping a power tool handle), it is at this location that the most representative evaluation of the vibration entering the hand is obtained. However, it is generally not possible to locate transducers at this point; the transducers will interfere with the normal grip used by the operator.