You can see that the uniform confined method gives the highest pressures peak overpressures. The pressures are very high because the method uses the entire cloud volume and a confinement strength of 10. However, in some locations the method gives lower pressures than other methods, especially in the far field.

Flammable releases from a rail tank wagon

The propane is delivered to the facility by tank wagon from a marshalling yard 10 km to the north. The deliveries take place once a week, involving two tank wagons, and are always during the day and never at night. The wagons are 10.6 m in length, 2.6 m in diameter with a volume of 54 m3, are raised 0.5 m above the ground, and are delivered with a fill-level of 80%. The propane is under the same conditions as in the sphere: under saturation conditions at atmospheric temperature (taken as 10oC).

There are many hazardous events that could be modelled for the tank wagons, including leaks during the unloading process. This tutorial will consider only the rupture of a wagon under normal operating conditions, a leak from the liquid side of a wagon, and a fireball produced by catastrophic rupture of a wagon under flame impingement. All events are assumed to occur while the wagons are at the unloading point 100 m south of the propane sphere.

Defining a folder and creating the Equipment data node for the wagon

Insert a Folder under the Study, and name the folder Tank wagons.

Create a copy of the propane pressure vessel inside the Tank wagons folder. The name Propane, Saturated 10 degC is also suitable for the tank wagon, and you do not need to rename the node.

The Catastrophic rupture Scenario is the only Scenario that was copied with the Equipment node that is relevant to the tank wagon, and you should delete all of the other nodes.

Open the dialog for the tank wagon Equipment node, and change the values for the following fields:

Setting the Elevation for the Rupture Scenarios

Edit the rupture Scenario and change the value for the Elevation to 1.8 m.