Determining Probability and Exposure per ANSI B11 for a Risk Assessment

[Life is a bowl of problems]

I am doing a Risk Assessment on a production machine using ANSI B11. It is not clear to me exactly what is meant by Probability level and Exposure level.
Probability is described as: "The likelihood that an individual, when exposed to the hazard, will suffer the consequence" and the levels vary by the degree that the hazard can be avoided. This seems to relate to the speed at which someone can recognize the danger and the time they have to react to it. For example a shearing knife that cycles continuously every second. My assumption is that the time to recognize and remove your hand from the hazard presumes that your hand is in the hazard zone which in my mind is between the blades. In this instance the Probability is "Almost Certain".

When for example a guard is added how does that impact the revised evaluation of the Probability? It's really not about avoidance any more but more about being excluded from the hazard zone. Does the Probability level change with a guard and if so does it go to zero.

I have similar questions about determining the level of Exposure: Exposure is describe as: "The relative frequency that an individual interacts with the hazard". The various levels are broken down into times per day, week, month or year. The initial assessment is done without any guarding or other mitigation. In my prior example of a cycling shear knife the Exposure would seem to be continuous. The same question arises as to whether the Exposure level changes when you add a guard that prevents access.

I also would like to understand how warning labels and training impact Exposure and Probability levels.

Any advice would be appreciated.

 

[Jboggs]

It sounds to me like you need a training session, and the advice and guidance of a safety professional.

 

[MintJulep]

Safety Engineering is a specialized area of practice that requires training. Not something that you can be expected to do properly on the spot without any.

So without being insulting or demeaning, if you need to ask these fundamental questions then you are not the right person to be doing this assessment.

Having said that, your questions themselves are good questions, so with training almost certainly you could do this - if you want to.

 

[Life is a bowl of problems]

I am certainly open to training. As a first step I would like to read a comprehensive description and discussion of the methodology of Risk Assessment. The granular level I am looking for seems to be hard to come by. I have purchased ANSI B11.TR3 but it lacks the details I seek. Any resources anyone could recommend would be appreciated.

Thanks,

 

[MintJulep]

B11.0 is not a bad place to start, but it's on the expensive side.

MIL-STD-882 has the great advantage of being free.