Open Gassy Systems

In an open system with gas production, the volume of gas can be obtained from Equation 10.3, and the volume calculated either for a toxicity limit, as for example the level called Immediately Dangerous to Life and Health (IDLH)  

In these equations, the extension is calculated as the radius of a half sphere, as it is easier to estimate a distance than a volume. This geometry is used to give an approximate idea of the order of magnitude of the area that may affected by gas or vapor release. This calculation is purely static and has nothing to do with emission and dispersion. Other shapes could also be considered. The assessment is by comparing the extension to characteristic dimensions, for example, of the equipment, plant, and site. 

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Open gassy system gas release in an open system. 

For gassy systems, open tests are preferable because ... 

In an open test, the pressure measured will be,the pressure in the containment vessel. If the test is done with the containment vessel closed and the nitrogen pressure control system off, then any permanent gas produced by the reaction will cause the containment vessel pressure to rise. Thus a constant containment vessel pressure indicates a vapour pressure system and a rising containment vessel pressure indicates a gassy or hybrid system. 

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