Once the automated testing equipment has been calibrated in accordance with the initial calibration procedures provided in these regulations, it may be used to determine the milk fat content of raw unhomogenized milk, provided it is operated in compliance with the following procedures:
A. Control Milk Samples. Milk samples to be used as control milk samples shall be prepared in accordance with the following procedures:
(1) Eight samples of natural herd milk shall be prepared in accordance with Regulation .06 of this chapter.
(2) These eight samples shall be tested three times by the reference method. The milk fat content of each sample shall be determined by averaging the results of the three tests to the nearest 0.01 percent. They shall contain a milk fat content within the range being tested by the equipment.
(3) The samples shall then be tested immediately by the automated equipment. The results of the three tests for each sample shall be averaged as provided in §A(2), of this regulation.
(4) If the standard deviation of difference between the average of the results obtained using the two methods does not exceed 0.06 percent, the equipment may continue to be used. If the (Sd) exceeds 0.06 percent, the equipment shall cease being used and be inspected to determine why the (Sd) exceeds this limit, be repaired, if necessary. and then recalibrated in accordance with the initial calibration procedures as set forth in Regulation .06 of this chapter. The Department need not be notified as to this recalibration.
(5) All control milk samples prepared shall be stored at temperatures between 35°40°F. A control milk sample may not be used beyond 7 days from the date of its preparation.
B. Daily Performance Checks. At the beginning of each day in which the automated testing equipment is to be used, the following tests shall be conducted:
(1) Upon proper zero adjustment, a performance check shall be made by measuring a control milk sample four times in the automated testing equipment. The results of the first two tests shall be disregarded and the results of the last two tests shall be averaged to the nearest 0.01 percent.
(2) If in the performance check the difference between the milk fat content of the control milk sample and the averaged results of the two tests conducted using the automated testing equipment (D) is greater than 0.06 percent milk fat, the determination shall be repeated using three additional control milk samples, each of which shall be tested in duplicate.
(3) If the difference (D) of any of the three additional samples is again greater than 0.06 percent milk fat, then the equipment shall be recalibrated according to the procedures provided for initial calibration as provided in Regulation .06 of this chapter.