Posted By P. Moore
Dear All

I am working on a risk assessment for the hand-arm vibration output of a machine.

I have consulted the manufacturer's technical data, the vibration emission data is given in m/s2 which state that it is "measured as per ISO 5349 based on 8 hour daily exposure".

The problem I have is that it gives an eight hour normalised emission level, not the simple vibration magnitude of ahv eq m/s2.

Consequently, I am unable to input this into the HSE HAV calculator which (I believe) requires the magnitude figure. From this figure it will then give an exposure level corresponding to the exact length of time of the equipment is in use.

Can anyone advise if there is a way to work out ahv eq m/s2 from what the manufacturer so that I can use the HAV calculator? Or have I misunderstood something?

Thank you!

Posted By P. Moore
Thank you for this.

I have contacted the manufacturer via our supplier. The response was that they have already provided the information they are obliged to!

Is there not a formula for working back to the magnitude from the normalised figure?

Posted By Adrian Watson
All measurements must be normalised to 8 hours. See Schedule 1 to The Control of Vibration at Work Regulations 2005 (SI 2005 No. 1093)

To use the HSE spreadsheet just input the vibration magnitude and exposure duration. This will give you a partial exposure period of m/s^2 A(8). Put in the remainder of the measurements, if any, and read the Daily exposure in m/s^2 A(8).

e.g. put in 2.5 m/s^2 x 4 hrs duration to give 1.8 m/s^2 (50 exposure points). then put in 2.5 m/s^2 x 8 hrs duration to give 1.8 m/s^2 (50 exposure points). This gives a total of 2.5 m/s^2 (100 exposure points).

Regards Adrian

Posted By Adrian Watson
Peter,

You cannot back calculate it as you don't know the measurement period. However, you don't need it as it is irrelevant providing that the peak value is not exceeded.

Regards Adrian