In the Toxic Lethality graph, the greatest effect distances are for the 1.5 m/s D weather outdoors, with a distance of about 450 m to a lethality level of 10%, which is approximately a fifth of the distance reached by the catastrophic rupture. The least stable condition, 3 m/s, B, reaches only about 200 m for 10% lethality outdoors.

If you open a GIS Results View for all three Weathers and view the Toxic Outdoor Lethality Footprint, you will see that the effects for 0.1% lethality do not reach the village or the town.

Defining the third scenario: toxic vapour from pipework

The vapour release is the rupture of a two-inch pipe attached to the top of the sphere. The line runs 3.4 m horizontally, then vertically downwards, and the rupture is assumed to occur 1 m from the ground.

Create the Scenario as a copy of the Line rupture, liquid Scenario, rename the copy to Line rupture, vapour, and change the input data as follows:

The release rate from the two-inch vapour line is similar to that from the one-inch liquid line, and the two pipework releases give very similar effect distances.