Hazard Rating System

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Auteur avatarGareth Green | Dernière modification 17/06/2024 par Gareth Green en cours de rédaction

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Description of the Hazard rating system employed by Stuga Machinery Ltd to classify and compare risk

Description

Machinery Safety Risk Assessments consist of the same basic considerations as any other type of Risk Assessment, and can be carried out by the following step-by-step approach:

  • Identify any hazards associated with the machine
  • Estimate the risk
  • Evaluate the risk

There are a wide range of tools and methodologies available to safety professionals to allow them to estimate the level of risk associated with each identified machine hazard, and determine whether or not the current level of risk is as low as reasonably practicable (ALARP).

One methodology which is frequently used in Machinery Safety Risk Assessments is known as the Hazard Rating Number (HRN) method.

How does the HRN method work?

Using the HRN system, once a machine hazard is identified, numerical values are assigned based on the following factors which aid in estimating and evaluating the risk related to a particular hazard:

  • Likelihood of Occurrence (LO)
  • Frequency of Exposure (FE)
  • Degree of Possible Harm (DPH)
  • Number of Persons at risk (NP)

Once the numerical values are assigned to each of the factors above, the hazard rating number (HRN) can be calculated by HRN = LO x FE x DPH x NP. The HRN number can then be equated with an overall risk level, using the tables below.

LO - Likelihood of occurrence score
Almost Impossible 0.033
Highly Unlikely 1
Unlikely 1.5
Possible 2
Even Chance 5
Probable 8
Likely 10
Certain 15


DPH Degree of Possible Harm Score
Scratch or Bruise 0.1
Laceration 0.5
Break Minor Bone 2
Break Major Bone 4
Loss of one limb, eye, hearing 6
Loss of two limbs or eyes 10
Fatatlity 15


FE - Frequency Of Exposure Score
Annually 0.5
Monthly 1
Weekly 1.5
Daily 2.5
Hourly 4
Constantly


NP - Number of Persons Score
1-2 Persons 1
3-7 Persons 2
8-15 Persons 4
16-50 Persons 8
50+ Persons 12


HRN - Hazard Rating Number
HRN Risk Level
0-1 Negligible
1-5 Very Low
5-10 Low
10-50 Significant
50-100 High
100-500 Very High
500-1000 Extreme
1000+ Unacceptable

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