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47 tween the two sites. Full strength fluids were affected by this increase in the range from 30 to <50%. A major reason for rule 11 to 15% of the time. these changes is the stepped augmentation of measured rates Other than the 50/50 mix, all fluids showed between-site in accordance with the CARs exemption. In the case of the HOT differences greater than 20% of the lower site value, 14 Octagon fluid, of the 18 data set pairs falling in the 30 to to 18% of the time. <50% difference range, 10 experienced a differential in aug- For thickened fluids at full strength and 75/25 mix, be- mentation, where the measured rates of one site were slightly tween-site HOT differences greater than 30% were expected below 10 g/dm2/h and thus were augmented by 6 g/dm2/h, 5 to 7% of the time and differences greater than 50% were ex- while the rates of the other site were over 10 g/dm2/h and thus pected 2 to 3% of the time. were augmented by 14 g/dm2/h. For Type I fluid, between-site HOT differences greater than 30% were expected 11% of the time and differences greater than 50% were expected 5% of the time. Examination of Site Separation Distance For the 50/50 fluid strength case, between-site HOT differ- To examine the relationship of distance between test sites ences were larger than for the other fluids, with HOT differ- and size of between-site HOT differences, data sets were ences greater than 20% about 29% of the time, greater than sorted by distance for the base case only. The tests were grouped 30% about 19% of the time, and greater than 50% about 14% into three distance ranges that each offered a reasonably large of the time. and similar number of tests. The distance range limits are shown in Table 31. The results for all data are shown in Table 31, and provide Summary of Differences--CAR Exemption Case the following findings: A secondary analysis was conducted wherein the measured data were adjusted according to the conditions described for At the shortest distance range for all fluids, there was only the CARs exemption case. The statistical analysis proceeded one case of between-site differences greater than 30%; as described above for the base case. For the Type I fluid base case, the frequency of tests gener- Table 30 summarizes the differences using the CARs ex- ating a percentage difference greater than 20% increased emption conditions. The total number of tests analyzed is from: lower than for the base case due to the exclusion of test sets 4% at the shortest distance; to when their actual precipitation rate was less than 2.0 g/dm2/h 25% at mid-range distance; and or when their augmented precipitation rate value exceeded 15% at the longest distance. 50 g/dm2/h. For the Clariant 2012 100/0 base case, the frequency of tests Fewer test sets are affected by the 120-minute capping rule generating a percentage difference greater than 20% in- as a consequence of the higher augmented precipitation rates creased from: and shorter HOT values. 1% at the shortest distance; to In comparison to the base case, there is a decrease in the 14% at mid-range distance; and frequency of differences in the range from 20 to 30% and an 21% at the longest distance. Table 30. Summary of between-site difference in fluid holdover time--CAR exemption case. SAE Clariant Octagon Kilfrost Kilfrost Type I MP IV 2012 MaxFlo ABC-S ABC-S Fluid 100/0 100/0 75/25 50/50 No Statistical Difference 69 36% 69 36% 69 36% 69 36% 9 31% Forced to Equality by 120 0 0% 10 5% 11 6% 0 0% 0 0% Minute Rule Test Sets < 20% 94 49% 81 42% 73 38% 82 43% 11 38% where Dif. in Endurance 20 to 30% 19 10% 15 8% 13 7% 18 9% 2 7% Time as % 30 to 50% 7 4% 13 7% 18 9% 17 9% 5 17% of Lowest Site is: > 50% 2 1% 3 2% 7 4% 5 3% 2 7% Total Test Sets Analyzed 191 100% 191 100% 191 100% 191 100% 29 100%

OCR for page 47
48 Table 31. Relationship of between-site differences and distance--all data 2007 to 2008. Type I Holdover Times in Snow - Measured Rates Number of tests where difference between sites is Distance Range (ft) 20% to 30% to 50% Total 29.9 % 49.9 % 4167 5052 64 3 67 96% 4% 100% 7017 13390 62 4 8 8 82 76% 5% 10% 10% 100% 27800 28500 78 6 6 3 93 84% 6% 6% 3% 100% Total tests 204 13 14 11 242 analyzed 84% 5% 6% 5% 100% Clariant 2012 100/0 Holdover Times in Snow - Measured Rates Octagon Maxflo 100/0 Holdover Times in Snow - Measured Rates Number of tests where difference between Number of tests where difference between Distance Range sites is Distance sites is (ft) Range (ft) 20% to 30% to 20% to 30% to 50% Total 50% Total 29.9 % 49.9 % 29.9 % 49.9 % 4167 5052 66 1 67 4167 5052 65 1 1 67 99% 1% 100% 97% 1% 1% 100% 7017 13390 70 6 1 5 82 7017 13390 68 8 2 4 82 85% 7% 1% 6% 100% 83% 10% 2% 5% 100% 27800 28500 73 14 6 93 27800 28500 68 16 6 3 93 78% 15% 6% 100% 73% 17% 6% 3% 100% Total Tests 209 21 7 5 242 Total Tests 201 25 9 7 242 Analyzed Analyzed 86% 9% 3% 2% 100% 83% 10% 4% 3% 100% ABC-S 75/25 Holdover Times in Snow - Measured Rates ABC-S 50/50 Holdover Times in Snow - Measured Rates Number of tests where difference between Number of tests where difference between Distance Range sites is Distance sites is (ft) Range (ft) 20% to 30% to > 20% to 30% to 50% Total 4167 5052 66 1 67 4167 5052 12 12 1% 100% 100% 100% 7017 13390 65 9 3 5 82 7017 13390 8 3 0 2 13 11% 4% 6% 100% 62% 23% 0% 15% 100% 27800 28500 67 17 7 2 93 27800 28500 10 1 2 4 17 72% 18% 8% 2% 100% 59% 6% 12% 24% 100% Total Tests 198 27 10 7 242 Total Tests 30 4 2 6 42 Analyzed Analyzed 82% 11% 4% 3% 100% 71% 10% 5% 14% 100%