ASTM D6743 Standard Test Method for Thermal Stability of Organic Heat Transfer Fluids
6. Apparatus
6.1 Test Cell - The test cell shall be a new, clean ampoule made from ASTM A-269 grade 316L stainless steel tubing, 25 mm (1 in.) outside diameter, 2 mm (0.083 in.) wall thickness. The test cell shall be 0.152 m +/- 0.003 m (6 in. +/- 0.125 in.) in length and sealed with compression fittings at each end.

NOTE 1 - Where tubing with SI dimensions is not readily available, the use of tubing with inch-pound dimensions is acceptable.

6.2 Heating Oven - The oven shall be capable of being controlled within +/- 1 °C (+/- 1.8 °F) at test temperature. The test temperature selected will typically be between 260 °C (500 °F) and 427 °C (800 °F), depending on the fluid being tested.

6.3 Bulb Tube Distillation Apparatus - This apparatus shall be capable of heating to at least 250 °C (482 °F) and pressure down to at least 0.1 mm Hg.

6.4 Dewar Flask - The flask is used to hold the test cells during cooling after removal from the heating oven.

6.5 Balance - The balance shall be capable of measuring mass to the nearest 0.01 g.

7. Preparation of Apparatus
7.1 Test Cell - The test cell used shall always be a clean, new ampoule. Reuse of ampoules is not permitted.

7.2 Cleaning of Test Cell - A new test cell shall be cleaned by washing with a suitable volatile solvent such as acetone and dried. (Warning - Use adequate safety precautions with all solvents and cleaners.)