I am estimating noise exposure at present for our "handymen service" and wanting to use manufacturers published information.  Manufacturers tend to quote sound pressure level and sound power level for each bit of kit.  I am assuming the pressure level is the one to use as this is intended to be the noise level experienced by the user rather than the power level (being the decibels emitted by the equipment).  The two quoted levels can often be 10 or so decibels different.  Does anyone have any thoughts please. 

Like all manufacturer information it is based upon a particular test method, generally using brand new equipment in a non-standard (laboratory) environment, even the substrates will not be identical to those of the work place.

Manufacturer data should be a starter for 10 in selecting lower hazard equipment - reality lies in the field with "in use" determination to take in to account reverberation and adjacent transmission.

For protection of workers against hand tool noise Sound Power would be your ready reckoner given Sound Pressure measureemnts are distance related and impacted by sound absorbption or reverberation.

Hi Booker

One of the first distinctions is what the noise measurements given by the manufacturer are measured in.

The most common are dB, dB(A) and dB(C). You could have a dramatic change in number just by changing the method of measurement.

For the purposes of assessing worker exposure it's usually dB(A) that you are interested in.

As Roundtuit has said that will depend on the condition of the equipment (rarely likely to be in the pristine condition that the supplier's information reflects) and how and where it is installed/used.

So, what you actually need to know is what real world exposure is likely to be. Except for providing some very coarse indication of preference at the time of procurement, the numbers given by a manufacturer are almost meaningless.

To do an assessment in the real world, you could start by simply using your ears. 

Then you might use the app on your phone if it is relatively sophisticated.

Then you could use a fairly basic noise meter calibrated in dB(A).

This might allow you to work out where there IS a problem or IS NOT a problem and in the former case there may be some simple fixes. LOTS of guidance on the HSE website.

Then you might need more sophisticated monitoring to check whether you still have a problem and/or to work out how big that problem is.

Hi Booker

Sorry, I'm old school and try to avoid apps!

But I do know that some use their phones to get an indication - how well some of them recognise the limitations of what they are doing, I cannot be sure.

Jus because I avoid apps doesn't mean that I am a dinosaur. I do see the merit in using modern technology where it has its place.

As example, drones to do inspections of bridges, BUT with an understanding that a drone is not a fully qualified structural engineer and has its limitations.

As I can see the limitations of an app on a phone to measure noise I probably wouldn't bother. Start with my ears and then move straight to one noise meter or another, depending on the scenario. Most scenarios are unlikely to need a particularly sophisticated meter.