Low vibration tools greatly reduce the risks of VWF but purchasers of power tools often face a lack of reliable data on the actual vibration levels produced by various tools in use. Many manufacturers’ data relates only to the vibration produced when the tool is free running, and vibration levels can increase dramatically under load.
The Health & Safety Executive (HSE) initially set a recommended safe limit of 2.8 m/s2 as the mean acceleration to which hands are subjected for an eight hour period. However, the ‘Control of Vibration at Work’ regulations of 2005 reduced the limits of exposure. The 2005 regulations define two action levels. The Daily Exposure Action Value (EAV) of 2.5 m/s2 is the level above which an employer must introduce a programme of controls to eliminate or reduce exposure and provide health surveillance to operators regularly exposed above the action value. A second limit, the Daily Exposure Limit Value (ELV) of 5.0 m/s2, is the level above which the employer must take immediate action to prevent further exposure to vibration.
Research commissioned by Norbar Torque Tools compared the vibration effects on the user between a typical impact wrench and Norbar’s Pneutorque® torque tool in a typical truck garage environment.
To measure the vibration, the researcher for the ‘Industrial Noise and Vibration Centre’ used an accelerometer attached to a typical impact wrench, as close as possible to the position of the operator’s hand. Tests were then carrier out using both an impact wrench and a Pneutorque tool to tighten ten truck wheel nuts to 600N.m.
Averaged over the ten bolts, the total vibration measured for the impact wrench was 18.8 m/s2, whereas Norbar’s Pneutorque® registered only 1.4 m/s2 during the same test. While a user of the impact wrench would reach their daily exposure limit (EAV) in just eight minutes of wheel changing, the Pneutorque operator could perform the same task continuously for over 24 hours without breaching the EAV limit.
