EVALUATION OF THE EFFECTIVENESS OF TOOL TIMERS FOR ESTIMATION OF DAILY EXPOSURE TIME TO HAND-ARM VIBRATION

The aim of this work is to evaluate the effectiveness of different types of tool timers for the estimation of daily exposure time for hand-transmitted vibration. The Health and Safety Executive (HSE) previously had little information available to advise on the merits (or otherwise) of tool timers as part of a vibration control program. Duty holders have begun to rely on tool timers to determine their workers’ exposure to hand-arm vibration. The results from this study will allow HSE to provide duty holders with better information regarding the use of tool timers in managing employee exposures to hand-arm vibration. This is ongoing work and additional tests are planned to improve the data set. Tool timers can be strapped directly onto the power tool or worn by the worker. They measure the amount of time a worker is using the power tool by detecting vibration or power flow. Some devices also measure the vibration emitted from the power tool. Using the time and a pre-programmed, or measured, vibration magnitude some devices then calculate HSE exposure points. This is with a view to notifying the user when they reach the Exposure Action Value (EAV) and/or the Exposure Limit Value (ELV) as defined in the Control of Vibration at Work Regulations 2005 (CVWR) 1 . Within this study six different tool timers were evaluated. In brief:  Two devices were mounted directly onto the power tool (“machine timers” according to BS/PD ISO/TR 19664:2017 2 ).  Two were wearable devices. One was wrist worn; the other was worn between the fingers of the operator (“exposure timers” according to BS/PD ISO/TR 19664:2017 2 ).  Two devices were in-line machine timers that monitor the power supply to the power tool (air flow or electric current). Table 1 describes each tool timer and how it functions in more detail.