Cochin laboratory

C H Ratio = 74 + 15 d

26 – 15 d where d is Specific gravity at 15 deg. C

CETANE INDEX (D 4737)

Provides a means for estimating ASTM Cetane number from density and recovery temperature measurements. The value computed from equation is termed as Calculated Cetane Index .It is a supplementary tool for estimating Cetane Number when standard method for determination (test engine) is not available or the quantity of sample available is too small and when the fuel is without Cetane Improvers.

C I =45.2 + 0.0892T_10N + (0.131+0.901B)T_50N + (0.0523+0.420B)T_90N + 0.00049(T²_10N – T²_90N) + 107B + 60B²

 D = Density at 15 deg.C in g/ml determined by test method D 1298

B = (e^{(-3.5) (D – 0.85)}) – 1 , T₁₀ = Temp(^oC)@ 10% vol. rec. by D86 and corrected to standard barometric pressure