Q6.(a) Describe the application of carbon dioxide for the extinguishment of surface fires in flammable liquids in quench tanks where the hazard is not enclosed. (7 marks) (b) Explain how the required concentration of clean agent heptafluoropropane can be determined. ( 8 marks) (c) Given that the minimum enclosure temperature anticipated is 20C, determine (by clear steps, assumptions and explanations) the weight of the fire suppressing agent FM-200 required to protect a heptane storage room with dimensions of 8m(L)7 m(W)3.5m(H). Correct to 1 decimal place. Table 6a and Table 6b may be useful for your calculation. (10 marks) Table 6a - HFC 227ea reference extinguishing and design concentration (extracted from ISO 14520-9) NUIt 1 The extingunshment values tor the Class B and the surtace Class A thels are determined by testing in accordance with ISO 14520-1:2015, Annexes B and C. NOTE 2 The minimum design concentration for the Class B fuel is the higher value of the heptane cup burner or room test heptane extinguishment concentration multiplied by 1,3 . NOTE 3 The minimum design concentration for Surface Class A fuel is the highest value of the wood crib, PMMA, PP or ABS extinguishment concentrations multiplied by 1,3. In the absence of any of the four extinguishment values, the minimum design concentration for Surface Class A is that of Higher Hazard Class A. NOTE 4 The minimum design concentration for Higher Hazard Class A fuels is the higher of the Surface Class A or 95% of the Class B minimum design concentration. NOTE 5 See ISO 14520-1:2015, 7.5.1.3 for guidance on Class A fuels