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Good vibrations

NCE CONTRACTORS FILE - Hand-arm vibration - Few would contest that contractors are best placed to reduce health and safety risks through better buildability. Morgan Est is taking decisive action on hand-arm vibration.

New legislation limiting exposure to hand arm vibration raises the prospect of labourers downing their power tools for the day after half an hour of work.

Contractors and designers alike are being forced to look at ways of limiting exposure to vibration.

'It is going to be a big thing for our industry. It is something we have addressed previously by trying to use low vibration tools, but with the new legislation we have to relook at what we are doing, ' says Morgan Est health and safety director Bob Coles.

'We're trying to design out the problem. There are some simple steps that we can take, such as putting retarders in concrete [to reduce the need for hand-held compactors], and we have to look at these. But designers themselves need to be considering what they are doing, ' he says.

The rm is already talking to its consultants. It is pressing them to take note of the new legislation. Morgan Est has also signed a partnership agreement with tool manufacturer Hilti, which will see its kit become the firm's preferred option.

In exchange, Hilti will provide training and support, helping Morgan Est's workers and managers select the tool with the lowest possible vibration for any particular job.

Hilti's attraction over other manufacturers is the way it presents vibration information.

'Information's structured in terms of productivity. They have identified how much work you can do with a particular tool or product in the course of a day. This simplifies our monitoring because if you don't exceed the amount of work that can be done, you won't have exceeded the legal limit, ' says Coles.

Selecting the right tool for the job can make a startling difference. There is little apparent difference between a Hilti HSA Stud Anchor with a 4.8kN pull out value and a HSC Safety Anchor with a 6.1kN pull out value. But the HSA anchor needs a 10mm diameter hole, 100mm deep, taking 18 seconds to drill and inducing 8.07m/s 2 of vibration. At this level of vibration the exposure action value - the point where the worker has to be put under 'health surveillance' is reached after 47 minutes limiting the number of holes drilled in a day to 156.

The HSC anchor, however, needs a hole only 40mm deep, albeit with a larger drill bit, and provides 30% more strength into the bargain. This takes 10 seconds to drill and induces vibration of 10.7m/s 2. Though the vibration is slightly higher the hole is much faster to drill, enabling 180 a day to be achieved.

'The enefit to designers is huge. Simply by specifying a different anchor he has increased productivity and provided 30% more strength, meaning the number of anchors could be reduced, ' says Hilti hand arm vibration manager Walid Hussain. 'The question is how many designers know about this-'

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