The cloud point of petroleum products and biodiesel fuels is an index of the lowest temperature of their utility for certain applications. Wax crystals of sufficient quantity can plug filters used in some fuel systems.

Petroleum blending operations require precise measurement of the cloud point.

This test method can determine the temperature of the test specimen at which wax crystals have formed sufficiently to be observed as a cloud with a resolution of 0.1°C.

This test method provides results that, when corrected for bias and rounded to the next lower integer (see 12.2), have been found equivalent to Test Method D2500.

This test method determines the cloud point in a shorter time period than required by Test Method D2500.

1.1 This test method covers the determination of the cloud point of petroleum products, biodiesel, and biodiesel blends that are transparent in layers 40 mm in thickness, using an automatic instrument.

1.2 The measuring range of the apparatus is from -65 to 51°C, however the precision statements were derived only from samples with cloud point temperatures from -50 to +6°C.

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.