Suppression by water and diluents

Since water is used as a common extinguishing agent, it will be included explicitly in our analysis of suppression. Other physical (nonchemically acting) agent effects could also be included to any degree one wishes. We shall only address water. We assume water acts in two ways  

The addition of water vapor is not addressed. We would have to specifically consider the species conservation equations for at least the products CO2 and H2O. Only water that is 

From the surface evaporation effect (2), we reformulate the surface energy balance (Equation (9.26e)) as the heat transferred (net) must be used to evaporate the fuel and the water at the surface, 

In other words, we replace Ahc by (1 — X, — XWjf)Ahc and L by Lrn everywhere in our stagnant layer solutions. The solution for flame temperature becomes, from Equation (9.56), 

These equations give us the means to estimate physical effects by the reduction of oxygen or addition of water on suppression. The equation for flame temperature with a critical value selected as 1300°C gives a basis to establish extinction conditions. 

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