ASTM D7899 Standard Test Method for Measuring the Merit of Dispersancy of In-Service Engine Oils with Blotter Spot Method
7. Sampling and Preparation of Samples
7.1 It is recommended that in-service oil or lubricant samples to be analyzed by this test method be sampled using procedures outlined in Practice D7418.
7.2 Protect samples from excessive temperatures prior to testing.
7.3 Do not test samples stored in containers with significant leakage. Discard and obtain a new sample if significant leaks are detected.
7.4 When analyzing samples using this test method, shake the sample vigorously until the sample is adequately homogenized and no sediment is adhered to the bottom or sides of the container.
8. Preparation of Apparatus
8.1 Before use, the instrument needs to be calibrated according to the procedure described in Section 10. This calibration can be performed by the end user.
8.2 Before analyzing samples, the instrument should be allowed to warm up for at least 15 min to ensure that the analyzer is stabilized.
9. Calibration of Apparatus
9.1 The calibration of the instrument shall be performed every time it is switched on. Perform the calibration according to the manufacturer's instructions. The camera brightness and contrast are automatically adjusted by measuring the two standard filters specified in 6.6. The spot dimension measurement is verified by measuring the printed spots specified in 6.7.
