the residence time in the heating spiral was 7 minutes at a temperature of 121 u00b0 c 249 8 u00b0 f the level in the stacking tower 17 was markedly lowered and was 33 to 39 thus resulting in a mean residence time of the pulp of 90 minutes at 75 u00b0 c to 77 u00b0 c 167 u00b0 f to 170 6 u00b0 f in comparison to the standard test 5 employed a tower temperature 90 u00b0 c 194 u00b0 f in the dispersion 15 the residence time in the heating spiral was 6 minutes at a temperature of 90 u00b0 c 194 u00b0 f the level in the stacking tower 17 was 59 to 68 thus resulting in a mean residence time of the pulp of 135 minutes at 62 u00b0 c to 63 u00b0 c 143 6 u00b0 f to 145 4 u00b0 f in comparison to the standard test 6 once again employed a lower temperature 90 u00b0 c 194 u00b0 f in the dispersion 15 the residence time in the heating spiral was 6 minutes at a temperature of 90 u00b0 c 194 u00b0 f the level in the stacking tower 17 was 69 to 85 thus resulting in a mean residence time of the pulp of 150 minutes at 50 u00b0 c to 61 u00b0 c 122 u00b0 f to 141 8 u00b0 f the temperature in the dissolving aggregate namely the ahlstr u00f6m drum 2 was set at a constant temperature of 50 u00b0 c 122 u00b0 f for all of the.