Technical
(usually a silver/grey decal); engine powered machinery, such as ride-on mowers or brushcutters are usually between 100 and 110 decibels.
Let’s look at a brushcutter or hand held hedgecutter with a two-stroke engine running at high speed. The operator is exposed to the full noise this generates. The CE decal and the operator’s instruction book will quote the tested value and this will be used to work out the level of hearing protection required when using that particular piece of equipment. Therefore, it’s actually pretty straightforward.
However, a ride-on mower is quite different. On a larger machine, there is much greater scope for moving the sources of noise away from the operator. The main culprit of noise generation is, of course, the engine. Air filter intakes, radiator cooling fans and the exhaust system all generate noise and all are directed away from the operator’s ear. Modern designs use baffles, anti-vibration pads and non-vibrating materials to keep noise levels as low as possible.
Machines do, however, still produce noise and, whilst clever design moves the noise away from the operator’s ear, this still effects the immediate area around the machine. So, the figure quoted on the silver CE decal is NOT what the operator is actually subjected to. It is the maximum noise level produced by the machine and it is usually found several metres behind it! A more accurate way of describing this reading would be the bystanders’ noise level.
So on a machine like a Ransomes Parkway 3, a heavy duty triple mower, popular with councils and contractors, the sound level on the CE decal is quoted as being 105dB, but in the operator’s instruction book the operator’s noise level is actually 85dB!
Which, rather conveniently is the upper exposure action value for an eight hour working shift. When you take into consideration that this value is the result of the manufacturer’s static test - and most operators will be mowing at an average speed of 3mph - then the actual noise at the operator’s ear is likely to be lower still. If we then look at the actual operating time, it’s more than likely going to be less than eight hours, especially if the machines are transported from site to site on vans or trailers during the working day.
So what are the limits?
The Control of Noise at Work Regulations 2005 define ‘exposure action values’ - levels of noise exposure which, if exceeded, require the employer to take specific action. There are ‘lower’ and ‘upper’ action values, the lower action value being 80dB, the upper action value at 85dB. The maximum exposure value is 87dB.
Therefore, we need to consider hearing protection at 80dB and have to act at 85dB. Nothing should exceed 87dB. So, how many of us actually measure operator noise levels, and how many just go by the warning decals on the actual equipment?
All CE approved machinery has to display the measured noise level
So, why not show the operator’s noise level on the machine as well? Well, in a roundabout way, we do. Remember all those bright yellow warning decals on every piece of machinery you own or operate? This particular warning decal says “READ THE OPERATOR’S
Above: Remember all those bright yellow warning decals on every piece of machinery you own or operate? This particular warning decal says “Read the Operator’s Instruction Book”
Left: All CE approved machinery has to display the measured noise level (usually a silver/grey decal)
PC OCTOBER/NOVEMBER 2015 I 127
INSTRUCTION BOOK” and it’s fitted to almost every CE approved machine in your fleet. So, if the operator follows the warning decals on the machine, he/she will read the manual and, therefore, find the actual noise levels which affect them. Many of these symbols will also be in blue and white, making reading the instruction not only important, but mandatory!
So, there is no excuse for not knowing what noise level the operator is exposed to and select their PPE accordingly. Whenever a new piece of equipment is delivered, the supplier should install it correctly and show you/your staff where the noise level test results are in the operator’s instruction book. This is a key part of the BAGMA Installation training course, which all dealer staff who install machinery should complete.
This begs the question, do you really need ear defenders to operate a machine at 85dB? And, if you do, what is the level of protection you actually need?
Ransomes Parkway 3
The only way to decide whether hearing protection is required or not is to measure the risks and assess them. Measurement should start with getting the right information from the operator’s instruction book and reviewing the actual exposure times. Then an informed decision can be made. Every business should have a clear policy regarding noise hazards and many decide that ear defenders are worn at 80dB and above.
Hearing defenders: Ear defenders basically come in two types - external defenders (EN352- 1) and ear plugs (EN352-2). Without the correct EN coding, they are either ear warmers or just headphones. They are not hearing defenders! Anyone using their own personal devices at work should have to prove that they are actually noise compliant.
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