Hydrogen Sulphibe Probit Function

[vickers65]

Hi guys

I'm hoping that somebody can help.

When assessing plant (QRA) for toxic risk, we would ordinarily use the Probit function built into Shell SHEPHERD, in order to assess the lethal concentration (for 1% fatality). We generally use 30 minute exposure for 1% fatality, but currently we are trying to use the same probit function for a 12 hour exposure.

Does anyone have any past experience in this? It has been suggested to us that the function has limitations for longer durations, and as such a different function should be used. Can anyone help with suggestions, or point me to any relevant papers? I'm stuck for ideas.

Hope you can help.

Cheers

Matt

[safetyuser]

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[link Point to another website Only the registered members can access]

Hi guys
When assessing plant (QRA) for toxic risk, we would ordinarily use the Probit function built into Shell SHEPHERD, in order to assess the lethal concentration (for 1% fatality). We generally use 30 minute exposure for 1% fatality, but currently we are trying to use the same probit function for a 12 hour exposure.

Does anyone have any past experience in this? It has been suggested to us that the function has limitations for longer durations, and as such a different function should be used. Can anyone help with suggestions, or point me to any relevant papers? I'm stuck for ideas.

Hope you can help.

YES WE CAN

Firstly, I strongly would not suggest to use 12hrs time exposure in a QRA for a numbers of reasons (mostly academics I would not bor here) but for sure you will result in very very little concentration corresponding to the specific Dangerous Toxic Load (DTL) and hence much larger impact distances.

Secondly, as you need ideas and papers I'll attach this from HSE UK (see attachments above).

Hope it helps

[vickers65]

Thank you very much for your quick response. This is a big help.

Thanks again.

Matt