Risk Assessment and Hazard Analysis
Hazard Identification
A hazard is: -
Anything that has the potential to do harm, a source of possible injury or damage to health.
A risk is: -
The likelihood of someone coming into contact with a hazard and the degree of injury or damage to health that could be caused should contact occur.
A hazardous situation is: -
Any situation where a person or persons are exposed to a hazard. Examples A moving belt on a conveyor would be a hazard. The risk would be the likelihood of someone coming into contact with an inrunning nip or being drawn along the belt by a protrusion and the severity of injury or damage to health that could be caused. An electrical enclosure containing voltages above 50v AC and 75v DC that has uncovered terminations is a hazard even though the enclosure may be kept locked and strict key control enforced. The reason for this is that if an electrician had to carry out diagnostic testing on a live enclosure they could inadvertently touch an adjacent terminal with a tool etc. The risk would be the likelihood of that happening and the severity of injury or damage to health that could be caused.
Risk Assessment Definition
A comprehensive estimation of the probability and degree of possible injury or damage to health in a hazardous situation in order to select appropriate safety measures
EN ISO 14121-1 Objective
To achieve adequate safety according to the state of the art and technical and economic requirements.
There are numerous ways of assessing risk involved with a hazard, one of which is the hazard rating number system. (HRN)
The practical risk assessment method that is used by Laidler Associates is Preliminary Hazard Analysis, which uses the HRN system. A sample risk assessment form can be found in the appendices at the end of this guide.
Numerical values are assigned to descriptive phrases relating to-
- The likelihood of occurrence (LO)
- The frequency of exposure (FE)
- The degree of possible harm (DPH)
- The number of persons at risk (NP)
A key to the number system is detailed on the risk assessment form in the appendices.
The hazard description is vital in understanding those risk assessments, unless otherwise stated, the risk assessment relates to the hazards in the normal operation of the machine. Where a specific risk is associated with that equipment, a separate risk assessment will be provided.
Where there is no control over the frequency of exposure, a worst-case scenario must be assumed, and a constant frequency is assigned.
Risk Assessment
Example Injury due to access to dangerous parts of machinery. The present guarding, partially fitted, allows access to the moving parts.
LO x FE x DPH x NP = H.R.N.
2 x 5 x 4 x 1 = 40
Degree of risk: = Significant
Clearly from this example we can see that the existing guarding, whilst offering a certain amount of protection, is not adequate and the degree of risk can be reduced further by fitting a guard that completely prevents contact with the hazard but does not affect the production.
Control Measure:
Fit a tunnel guard that prevents all access to the moving parts in accordance with EN953 and EN294.
After control measures fitted:
LO x FE x DPH x NP = H.R.N.
0.1 x 0.1 x 4 x 1 = 0.04
Degree of risk: = Negligible
The control measure has detailed the machinery needs additional guarding, and has detailed the Standards to which you should construct that guard in accordance with. EN Standards will be used for the correct control measure where those Standards exist. The control measure is deliberately left non-specific in its description in order to allow the designer of that guard some scope of flexibility in his approach. If we detail an exact specification to a guard or control measure, we effectively tie your hands. Our assessments are one method of compliance and should you find an alternative way to achieve compliance, then we would welcome your suggestions. Our engineers are available to give specific advice to you outside of these assessments should you require it.
As mentioned at the start of this section, EN ISO 14121-1 is the main standard for risk assessment for machines and is harmonised to the Machinery Directive. It lays down principles forrisk assessment and highlights a number of different methods, including the method that Laidler Associates use and was documented on the previous pages.
Also included within the standard is a table giving examples of hazards, hazardous situations and hazardous events. A simplified version of this is included within the Appendices of this guide. The original table in the standard gives more detail as to the kind of hazards or hazardous situations that can occur. Anyone involved in a risk assessment project for machinery should refer to the Standard list as matter of course unless they are totally confident in their knowledge and ability to carry out the assessment.
Contact Us
Still not found what you were looking for? Confused by all the different regulations, directives and standards?
Why not contact us and get specific answers to your questions along with practical solutions by using the contact form below:
