ASTM D3104 Standard Test Method for Softening Point of Pitches (Mettler Softening Point Method)
5. Apparatus
5.1 A METTLER TOLEDO dropping point cell shall be used to determine pitch softening points by this test method. These commercially available instruments consist of a control unit with a digital temperature indicator, with furnace built in or attached, sample cartridges, and accessories. The control unit automatically regulates the heating rate of the furnace. The softening point is indicated on the readout, and the heating program stopped, when the sample flow triggers the softening point detection. A general view of the contents of a METTLER TOLEDO dropping point instrument is shown in Fig. 1 (old instrument) and Fig. 2 (new instrument).
5.1.1 Integrated or Separate Control Unit - The control unit shall provide a continuous, linear temperature increase from 25 °C to 250 °C at a rate of 2 °C/min. A digital readout shall indicate the temperature to 0.1 °C throughout.
5.1.2 Integrated or Separate Furnace Unit - The furnace unit shall be capable of heating one or two sample cup assemblies, as described in 5.1.3, at a linear rate of 2 °C +/- 0.3 °C/min. It shall include a sensing system capable of detecting the softening point with a precision of 0.1 °C.
5.1.3 Sample Cup Assembly - A cup of chromium-plated brass, or of aluminum, or of stainless steel conforming to the requirements for Type 303 (UNS S30300) stainless steel as prescribed in Specification A314, with the dimensions shown in Fig. 3. It shall be placed in the assembly so that the pitch sample softening point will be detected when it has flowed down a distance of 19 mm.
6. Reagents
6.1 Xylene, industrial grade.
6.2 Benzoic Acid.
