I'd query the results if you're saying that field test results exceeded the manufactuerers data as that's never been our experience. I think even the HSE advise a doubling of figures if you're just going to run with manufacturers data.

Also, make sure everyone understand what "trigger time" is as opposed to the time a task may take, with the tool sitting idle for long periods.

Vibration readings are notoriously unreliable. And I was told that by a vibration specialist!!.

In line with Claire’s comment, I attended a joint eff/HSE seminar on vibration some time ago and the HSE vibration guru’s said the vibration measurements are notoriously unreliable, with consecutive measurements of the same piece of kit using the same measuring equipment often varying by 50% or more.

The HSE have revised their previous advice on doubling up the manufacturer’s data (don’t) and this can be found on the HSE HAVS page.

Although I don’t have any experience of measuring the vibration levels of the specific tools that you refer to they do appear to be particularly high and I personally would be a little sceptical unless these were really old tools (which I assume they aren’t if there is manufacturer’s vibration data available). I have been dealing with grounds maintenance kit for quite some time including chainsaws, strimmers etc with nothing like 27m/s. In fairness and as I have already said, I haven’t experience of orbital sanders, so perhaps your readings are genuinely demonstrative of that kit, but I’m not convinced (if that isn’t repetitive or contradictory!)

Having said that the HSE have changed their advice, I also recognise that the manufacturer’s data is unlikely to be truly representative of the vibration in operational conditions. In an attempt to try and come to a reasonably robust figure without resorting to the measurement route I spent quite some time talking to the technical manager of the manufacture whose grounds maintenance kit we tend to use to try ‘agree’ and approach that we both felt would be reasonably demonstrative of ‘in service ’ vibration levels.

I am not sure what to suggest as the best course of action. Some might argue that having carried out the measurements, that you have opened Pandora’s box and have little choice but to go with that. You could retest with another consultant, but that’s an additional cost and doesn't guarantee too much. The best advice I can give is to discuss your concerns with the consultant who did your measuring and query why the readings are disproportionately high and seek a ‘reassurance’ retest. You could also ask for and ensure that you are satisfied with their methodology used, although you should have already done this before employing them. If you subsequently decide to go with the manufacturer’s data I suggest you read the HSE HAVS site about using this as an initial assessment.

Hope you get it sorted.

After having extensive experience in the field over many years from the early 1990's [With the HSE and others] when mobile test kit was in its very early infancy I have found that there are stories, fairy tales and manufacturers data so in all cases undertake your own measurements [via outside or in-house people] and go from there remembering that it is a judge and not the HSE who decides a case in a court and you must prove that you have done all that it was reasonably practicable to do

NB: Also remember that you should be testing people not just kit as its the dose a person gets that the courts focuses on

I think everyone has got horror stories regarding this subject.
We use impact wrenches as part of our installation process and maximum 'trigger time' has reduced there use to 45 minutes in an 8 hour day.
Seeing as the task can take up to 4 hours, we had to look at other ways of undertaking the task and settled on the tried and trusted method of a couple of spanners and a bit of brute force.
I'm now expecting the incidence of muscle strains to go up................yer cant win eh, sheeeeeeeesh.