ASTM D3707 test method for storage stability of water-in-oil emulsions
ASTM D3707 standard test method for storage stability of water-in-oil emulsions by the oven test method
7. Procedure A - 48-h Test
7.1 After careful preparation of the sample to obtain homogeneity (described in Section 6), transfer 100 mL to a graduated 100-mL cylinder. Insert the vented stopper.
7.2 Place the cylinder in a convection oven maintained at 85 +/- 1°C (185 +/- 2°F) for a period of 48 h. Take care to position the graduated cylinder in the oven generally in the center and raise at least 75 mm from the bottom of the oven, to ensure temperature uniformity.
NOTE 1 - When carrying out a number of tests at the same time, arrange the cylinders to avoid developing temperature variations in the oven due to inadequate convection. The number of tests carried out at the same time should, for the same reason, also be restricted.
7.3 Withdraw the cylinder from the oven and allow to stand at room temperature, 21 +/- 3°C (70 +/- 5°F), for a period of 1 h.
7.4 Observe and record:
7.4.1 The amount of oil separated, percent volume and
7.4.2 The amount of water separated, percent volume.
7.5 By means of a 10-mL pipet, withdraw aliquots in the following order:
7.5.1 With the pipet tip located exactly at the 80-mL mark, slowly withdraw a 10-mL sample and transfer to a small glass vial. This is designated as the upper layer sample.
7.5.2 With the pipet tip located exactly at the 15-mL mark, slowly withdraw a 10-mL sample and transfer to a small glass vial. This is designated as the lower layer sample.
NOTE 2 - In the event that the amount of separated water equals or exceeds 10 % by volume then the determination of the water content of the lower layer is an optional procedure.
7.6 Determine the water content, as percent weight, of the upper layer and lower layer samples, after shaking, by the procedure given in the Annex. Use a 0.05-mL sample transferred by means of a glass microsyringe.
8. Procedure B - 96-h Test
8.1 This procedure is identical to that described under Section 7 except that the time period in the convection oven (7.2) is changed from 48 h to 96 h.
