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alan w houghton  
#1 Posted : 01 May 2012 15:59:46(UTC)
Rank: Super forum user
alan w houghton

Hi

I have completed a noise assessment for our workshop

For 8 minutes whilst our punch press in operation we have acheived max noise of 96dBA
I have looked at reducing the noise before hand by placing rubbers underneath the feet etc

I now find I need hearing protection with a SNR25 value to ensure noise is reduced to between 70-80 whilst wearing hearing protection

My question
How to I work out noise exposure on a daily basis when this is my loadest noise yet 90% of the time we don't fabricate such noise levels

In other words how long can we have this noise level as I thought it was noise x length of time exposed but can't grasp how I would report this.
Thanks in advance
Alan




KAJ Safe  
#2 Posted : 01 May 2012 16:07:20(UTC)
Rank: Forum user
KAJ Safe

Alan

If you look at the guidance (L108) on the noise regs (pg 37 onwards), you will see there is a chart which helps work out such things - the charts actually starts on pg 42 but I would read the guidance first.

leadbelly  
#3 Posted : 01 May 2012 16:12:49(UTC)
Rank: Super forum user
leadbelly

Try the appropriate calculator here: http://www.hse.gov.uk/noise/calculator.htm

LB
alan w houghton  
#4 Posted : 01 May 2012 16:21:53(UTC)
Rank: Super forum user
alan w houghton

LB

I tried the calculator, but means nothing to me
:-(

Thats what confused me in the first place, what do the results mean
alan w houghton  
#5 Posted : 01 May 2012 16:43:35(UTC)
Rank: Super forum user
alan w houghton

Cuttel180003

Got it now cheers mate
Jobe  
#6 Posted : 01 May 2012 16:58:04(UTC)
Rank: New forum user
Jobe

Alan, sent you a PM.

Regards,
JJ Prendergast  
#7 Posted : 01 May 2012 17:02:19(UTC)
Rank: Super forum user
JJ Prendergast

For every 3db change in noise levels, the noise energy either doubles or halves (forgive me if not quite the correct technical terminology). This then also either doubles or halves the time 'allowed' to have the same noise 'dose'

The calculation is usually worked out as 90db for 8hrs

Therefore an increase from 90-93db is doubling the noise energy

A further increase from 93-96db is another doubling of the noise energy

Therefore 90-93 would reduce your permitted time to 4hrs.

Increasing from 93-96db would reduce your permitted time to 2hrs.

In summary 96db over 2hrs = 90db over 8hrs.

This is a rule of thumb estimate.
Heather Collins  
#8 Posted : 01 May 2012 17:15:39(UTC)
Rank: Super forum user
Heather Collins

JJ Prendergast wrote:
The calculation is usually worked out as 90db for 8hrs


Not since the Control of Noise at Work Regs 2005 introduced an Upper Exposure Action Value of 85 dB it isn't. Your theory is right - halve the time for every 3 dB increase, but you need to start at 85 dB for 8 hours, not 90.
JJ Prendergast  
#9 Posted : 01 May 2012 17:23:14(UTC)
Rank: Super forum user
JJ Prendergast

ok, guess that works out as about 1/2 hr at 96db = 8hrs at 85db
Canopener  
#10 Posted : 01 May 2012 21:07:40(UTC)
Rank: Super forum user
Canopener

Ok here goes. Nobody else has said it yet, and that is because the first person that does often gets a bit of a slating, however.

On the one hand you say that you have completed a noise assessment while on the other you’re unsure of how to calculate the LEPD, and that the HSE noise calculator means nothing to you and that you don’t understand the results!!!!!

Are you comfortable, confident that you are competent to carry out a noise assessment? Looking from the outside with the comments that you have made so far I would suggest probably not and that you haven’t actually carried out a noise assessment either but rather probably measured the LEQ of a single noise source (I assume A weighted?) and made a time measurement. So far so good, but this is unlikely to give you an accurate reflection of the LEPD. To use SNR or HML accurately you need to be able to measure C weighted levels as well.

The information that the other posters have provided is all ‘good stuff’, the 3dB rule etc.

The HSE noise calculator is really easy to use and more accurate than the nomogram, but in practical terms the easiest and generally most accurate way to get an accurate LEPD is to use some form of dose meter. Your alternative is to make a number of LEQ measurements and ‘plug’ these into the noise calculator with the appropriate exposure duration.

Sorry, but with the best will in the world I do wonder if you need to take a step back and as a MINIMUM get the books out, do your research on noise measurements etc and FULLY understand the nature of noise, how it is measured, how to calculate an LEPD, and how to use SNR etc before going to much further. Ideally you should attend a noise measurement/assessment course by a reputable provider. The danger of not understanding what you’re doing is that you might not protect where you should be, or that you might be asking your employer to fork out on something they don’t need to Either way this is not particularly good news.

Right, I’m now off to get my stab vest and hard hat on and wait for the inevitable!
Graham Bullough  
#11 Posted : 02 May 2012 00:17:41(UTC)
Rank: Super forum user
Graham Bullough

canopener - Though I've had little involvement with noise and vibration issues in recent years, I generally agree with your comments and suggestions above, including the use of a personal dosemeter. I recall from my latter years with HSE over 25 years ago that HSE occupational hygienists used such devices in workplaces to get accurate measurements of actual noise exposures when helping inspectors to determine if existing personal protection and/or engineering noise control measures were sufficient or not. A similar case can be made for using vibration dose meters now that effective devices have been developed and become available during more recent years.

Alan W H - Hope you are not too fazed by the responses, especially canopener's, to your thread. It can be argued that you have demonstrated competence by recognising the limit of your knowledge and choosing to ask other OS&H people for practical advice and suggestions via this forum. As mentioned above, my own knowledge of noise and vibration issues is admittedly rusty. Therefore, if faced with a noise situation like the one you describe, I'd need to update myself with current legislation, terminology and standards - even though I think I know the basics, i.e. try to reduce noise at source by available practical measures. If such measures are not available or insufficient, there is no little or no option but to rely on suitable PPE and ensure that those to be protected have sufficient understanding of its limitations.

Similar advice applies to various other situations in OS&H and also other professions. For example, many years ago, I asked an HSE medical adviser how he managed to remember all the information he surely needed to know when he previously worked as a general practitioner. His answer seemed very honest because he replied that neither he nor other doctors could expect to know let alone remember everything about the medical conditions which they might encounter as GPs. They should obviously have a good working knowledge of common or critical conditions with which their patients, young and old, might arrive at GP surgeries, and be able to give appropriate advice and/or prescriptions for them, or instigate appropriate action for critical conditions which need urgent attention, e.g. meningitis in young children. As for other conditions, medical skill lay in trying to get appropriate information from or about patients, including samples where appropriate, and then looking up textbooks, discussing with colleagues, etc., with a view to making diagnoses. Gaining sufficient time to do this explains to some extent why GPs tend to give some patients interim advice and tell them to come back within a few days or a week, etc., if their conditions do not clear up. Thus, by the time a patient returns if necessary, the GP has hopefully had time to 'mug up' on possible conditions and appears very knowlegeable about what to do.

As some doctors may get upset if they happen to see the above comments, I'd better stress that they are simplistic ones based on my recollection of what one doctor told me years ago as someone with no medical training, plus comments by some medical friends during the intervening years.
alan w houghton  
#12 Posted : 02 May 2012 08:00:47(UTC)
Rank: Super forum user
alan w houghton

canopener
I understand exactly what you say and would agree - I have limited knowledge regarding noise and have booked myself a training day to get a good understanding of the requirements and how to measure etc
As Graham has pointed out thats why I have come to gain advise of the people whom do know about noise as the risk is today I don't want to wait till after I have done my training so I am trying to ensure I deal with it the best I can for now and then take it forward after my training
Thanks everyone for your good avice
Alan
ctd167  
#13 Posted : 02 May 2012 13:33:56(UTC)
Rank: Forum user
ctd167

Am i being too simplistic in suggesting that during the noise generating activity, the area is considered to be a noise hazardous area and therefore ear protection should be worn?
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