Uncertainty in the sizing calculation

The general approach to uncertainty followed here is that of Duxbury[1,2]. The overall safety factor, F0, may be represented as the product of a number of sub-factors each taking account of particular features  

It is up to the designer to determine what sub-factors need to be included for any particular application. Possible sub-factors include  

For computer simulation (see Annex 4), it will be necessary to correlate.the kinetics of the reaction. The results of the relief sizing calculation will be sensitive to the chosen value of the activation energy.  

If an applicable version of the HEM has been used, then a safety factor may not be required for relief sizing, but one may be needed for sizing of any downstream disposal system (since for disposal system sizing, underestimation of the flow is unsafe). 

It is difficult to treat the following causes of uncertainty by means of a safety factor  

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