Hi

We are looking at vibration risk from a hand held grinder and using the HSE hand arm vibration calculator to calculate maxiumum acceptable exposure duration in hours and minutes.

The suppliers manual gives a vibration magnitude of 5ms2 and a uncertainty K of 1.5ms2. Is the K value used in the calculation?

Regards

So the supplier is telling you the level can be somewhere between 3.5 and 6.5 (value +/- uncertainty)

Working worst case scenario use 6.5 in the HAV's tool

Ok i use a handy Free Hav Calculator on my android phone  https://play.google.com/store/apps/details?id=com.toolminder.havcalculator&hl=en_GB  Its pretty good and i can do calculations as i go round the sites.

Just found out you can use it too if you have a windows phone https://www.microsoft.com/en-gb/store/p/hav-calculator/9wzdncrdq7kx

I input the 6.5 m/s2 which is the Exposure magnitude

This gave me 85 points per hour

So the trigger time to reach for...

EAV 2.5m/s2 A(8) is 1 hour and 11 minutes

ELV 5m/s2 A(8) is 4 hours 44 minutes

High risk (above the ELV)

Employees who regularly operate:

• Hammer action tools for more than about one hour per day; or
• Some rotary and other action tools for more than about four hours per day.

Employees in this group are likely to be above the exposure limit value set out in the Regulations. The limit value could be exceeded in a much shorter time in some cases, especially where the tools are not the most suitable for the job.

Medium risk (above the EAV)

Employees who regularly operate:

• Hammer action tools for more than about 15 minutes per day; or
• Some rotary and other action tools for more than about one hour per day.

Employees in this group are likely to be exposed above the exposure action value set out in the Regulations.

Hope that helps

Edited by user 18 February 2017 13:19:38(UTC)  | Reason: added Windows Phone link

I agree with the above post, I would definately purchase a new grinder.

Any grinder which can only be used for less than or up to a maximum time of 1 hour should be replaced to prevent over-use.

When assessing the magnitude of tools I use this site. You might have to register but it helps when purchasing new tools as well. https://www.operc.com/havtec/havinfo.asp

Yep daily x 7

Originally Posted by: Bigmac1

WTD only applies to those who dont opt out and its averaged out over a period. A working week is in quite a few cases 7 days. Hence if a shift pattern meant 7 day working you wouldnt put your grinder down on day 6 would you. 

Yes to the question of putting it down on day 6. If you have reached the exposure limit not to do so may be an offence ... for the company and for the operator, http://www.hse.gov.uk/vibration/hav/advicetoemployers/index.htm 

Its a while, and a couple of companies ago ... 

We used Reactec HavMeter (others are available) The management and control of the system should have been simple enough but was a little problematic.

Edited by user 05 June 2017 21:13:24(UTC)  | Reason: spillchocker

We looked at this system (and similar) following a hard-sell from a rep, but for us they were prohibitively expensive and are relaint on the data input against each tool, so typically the manufactueres.  Instead we tag each tool with points per five minutes trugger time which for new tools we base on the manufacturers data; however we field test tools over time so that we get an accurate picture of the vibration characteristic plus can demonstrate and understand any degrading of the tool over time through wear and tear.  We're a liitle way off but we hope to use that data to inform replacement frequencies and so gather whole life cost data for the power tools generally.

Meant to add that what features heavilly is education and informationj provided to end users so that they understand and can to a degree self-manage exposure.

Originally Posted by: paul.skyrme

SNS,

That device is measuring trigger time from the parameters stored in the little memory disk it seems.

I am guessing that the parameters stored in there by the master system for each tool will be the tool OEM data?