Impact Wrench (air)
vibration exposure
How much hand-arm vibration a impact wrench (air) delivers, how fast it uses up a day's exposure, and what to do about it. Typical use on site: 30 mins.
A typical 30 mins on trigger is about 49 points, which is under the action value, leaving room for other tools in the same day. Work it out for a whole day, with every tool, in the free HAVS calculator.
Controls that work
- Choose the lowest-vibration tool that does the job, and check the declared magnitude before you buy or hire.
- Keep tools maintained: blunt blades, worn bearings and unbalanced discs all push the magnitude up.
- Rotate operatives so nobody carries the whole day on one tool, and plan the rotation against points, not guesswork.
- Cut trigger time: pre-drill, use the right consumable, let the tool do the work instead of leaning on it.
- Keep hands warm and dry. Cold and wet make the same exposure more harmful.
- Health surveillance for anyone likely to be regularly exposed above the action value, and a way to report tingling or numbness early.
- Anti-vibration gloves are not a control. They do not reduce the exposure that counts, and they can make grip worse.
Questions people ask
How long can someone use a impact wrench (air) in a day?
At 7 m/s² it reaches the Exposure Action Value (100 points, A(8) 2.5 m/s²) after about 1 h 1 min on trigger and the Exposure Limit Value (400 points, A(8) 5 m/s²) after about 4 h 5 min. Trigger time is time the tool is actually running in the hands, not the length of the shift. Control of Vibration at Work Regulations 2005. Guidance, not legal advice.
Where does the magnitude come from?
7 m/s² is a typical in-use figure for this class of tool. Manufacturers' declared values are measured under ideal conditions and often understate real use, which is why HSE suggests treating them cautiously. If you have measured your own tool, your figure takes precedence.
What are exposure points?
HSE's way of adding up vibration across a day without logarithms: 2 × (magnitude)² × (hours on trigger) per tool. Add the tools together. 100 points a day is the action value and 400 the limit value.
What if two people share the tool?
Each person's exposure is their own trigger time. Sharing a tool between two operatives halves each one's points, which is why job rotation is the first control on most sites.
Do anti-vibration gloves help?
Not as a control. They do very little to the frequencies that cause HAVS and are not accepted as a way of reducing the assessed exposure. Warm, dry hands matter, but the answer is less exposure, not a different glove. Guidance, not legal advice.
Pick the tool, get the assessment
Choose the tools in the SiteLynx RAMS editor and the HAVS assessment fills in with the points, the rotation and the health surveillance note. Signed on site on a phone. 14 days free.
Start free trial