The international standards ASTM D3104, ASTM D3461, ASTM D3954, ASTM D6090 and AOCS Cc 18-80 are specifically based on automatic dropping point and softening point measurement with METTLER TOLEDO's Dropping Point instruments.
For an overview of international norms and standards for dropping and softening points including manual methods, visit www.mt.com/MPDP-norms.
The ASTM D3104 and D3461 standards are called softening point according to METTLER TOLEDO or METTLER TOLEDO's cup-and-ball. They are based on the automatic softening point detection principle with the METTLER TOLEDO Dropping Point instruments. In the D3104 standard, no extra weighting of the sample in the cup is required, whereas in the D3461 standard, a lead ball of specified dimensions is required to enforce the flow of the sample from the cup. In both cases, the test is performed in a furnace and the softening point temperature is detected and recorded automatically. The ASTM D36 or ISO EN 1427 methods specify the softening point test according to the ring-and-ball method. In contrast to METTLER TOLEDO's standards, a different test setup including liquid-medium bath heating is used. The ASTM D566 or ISO EN 2176 are the basis for lubricating grease dropping point testing, using either a liquid medium bath or an aluminum furnace block heating. In both cases, the sample needs to be prepared in the dropping point cup according to an exactly specified procedure. In both standards, the dropping point event is detected manually. The IP 396 standard adheres to these standards in respect to sample preparation, but is based on a dual heating ramp procedure (See diagram) and automatic dropping point event detection.
METTLER TOLEDO's Dropping Point instruments allow fully automated dropping point detection of lubricating grease exactly according to the requirements of the IP 396 standard. In all standards, tight limits for repeatability and reproducibility are given, which serve as a guideline to assess the result quality. In the bitumen/pitch/asphalt standards, these specifications are tight, whereas in the lubricant grease standards the corresponding values are comparatively high. This is due to the fact that the sample integrity of the grease is destroyed during the heating procedure, especially if temperatures above 200 °C need to be applied.