RON/MON Octane Test Engine standardization is dependent solely on TSF blend determinations. Every sample fuel octane number determination shall be performed using an octane engine that has been qualified as fit-for-use by rating the appropriate TSF blend. Qualify the RON/MON Test Engine using the appropriate TSF blends in accordance with ASTM D2699 RON/ASTM D2700 MON test method. The octane number of samples can be rated (RON) by referring to the TSF Blend rating procedure (Bracketing Procedure) in the video.
Qualify the MON/RON Test Engine using the appropriate TSF blends in accordance with the following conditions:
At least once during each 12 h period of rating.
After an engine has been shut down for more than 2 h.
After a unit has been operated at non-knocking conditions for more than 2 h.
After a barometric pressure change of more than 0.68 kPa (0.2 in. Hg) from that reading made at the time of the previous TSF blend rating for the specific O.N. range.
When the bracketing procedure is utilized to determine the TSF blend rating, set the cylinder height, compensated for the prevailing barometric pressure, to the guide table value for the O.N.ARV of the selected TSF blend.
RON Test Engine Fit-for-Use Procedure—80.2 to 100.0 O.N. Range:
Select the appropriate TSF blend(s) from Table 2 that are applicable for the O.N. values of the sample fuel ratings tested or to be tested during the operating period.
Rate the TSF blend using the standard IAT based on the prevailing barometric pressure.
If the untuned TSF blend rating is within the untuned rating tolerances of Table 2 for that TSF blend, the engine is fit for use to rate sample fuels within the applicable O.N. range. IAT tuning is not required.
If the untuned TSF blend rating is more than 0.1 O.N. from the O.N.ARV in Table 2, it is permissible to adjust the IAT slightly to obtain the O.N.ARV for that specific TSF blend.
If the untuned TSF blend rating is outside the untuned rating tolerance of Table 2, adjust the IAT within prescribed limits to obtain the O.N.ARV for that specific TSF blend.
RON Test Fit-for-Use Procedure—Below 80.2 and Above 100.0 O.N.:
Select the appropriate TSF blend(s) from Table 3 that are applicable for the O.N. values of the sample fuel ratings tested, or to be tested, during the operating period.
The rating tolerances of Table 3 are determined by multiplying the standard deviation of the data that established the O.N.ARV of the TSF blend and a statistical tolerance limit factor K for normal distributions. Using the standard deviation values for the TSF blend data sets of 100 or more values and K = 1.5, it is estimated that in the long run, in 19 cases out of 20, at least 87 % of the test engines would rate the TSF blend within the rating tolerances listed in Table 3.
Rate the TSF blend using the IAT specified for the prevailing barometric pressure. Temperature tuning is not permitted for these O.N. levels.
If the TSF blend rating is within the rating tolerance, the engine is fit for use to rate sample fuels having O.N. values within the applicable range for that TSF blend.
If the TSF blend rating is outside the rating tolerance, conduct a comprehensive examination to determine the cause and required corrections. It is expected that some engines will rate outside the rating tolerance, at one or more of the O.N. levels, under standard operating conditions. Control records or charts of these TSF blend ratings can be helpful to demonstrate the ongoing performance characteristic of the unit.