Rationale

Section 14.4.5.2 contains instructions for performing fit for use testing using a Toluene Standardization Fuel of known value. The instructions state ‘…it is permissible to adjust the detonation meter settings to obtain a knockmeter reading of 50 ± 2 divisions.’ When testing unknown samples, the cylinder height is adjusted to obtain this knockmeter reading as appropriate detonation meter settings would have been determined either during fit for use testing or while establishing standard knock intensity on a Primary Reference Fuel. When performing fit for use testing, section 12.2.4 instructs to ‘…set the cylinder height for the O.N., compensated for the prevailing barometric pressure, to the guide table value for the O.N.ARV of the selected TSF blend.’ Therefore, the only practical way to obtain a knockmeter reading of 50 ± 2 divisions, when qualifying fit for use on a TSF, is to adjust the detonation meter settings. Currently that is not clear as the text implies the adjustment of the detonation meter is optional. This ballot attempts to clarify the instruction by using mandatory wording.