ASTM D831 Standard Test Method for Gas Content of Cable and Capacitor Oils
7. Calibration of Apparatus
7.1 Calibration and conditioning of the apparatus are often done by the manufacturer. If this has not been done, or if a check is desired, the following procedures may be used:
7.1.1 Clean the glass assembly with a cleaning solution, wash with distilled water, and dry. Weigh the empty glass apparatus with a slight film of grease on the stopcocks. Record the weight in grams (or volume in millilitres) as W. Fill the glass apparatus between stopcocks B and C and point M with distilled water and weigh. Record the weight in grams (or volume in millilitres) as R. The volume represented by the difference between W and R added to the volume of the pressure gage (Note 4) is the volume, V, of the tester in millilitres. The volume, Vd, of the degassing chamber enclosed by the oven and the volume, Vt, of the cold trap covered with coolant may be determined similarly. Correction for temperature of water may be made, but is an unnecessary refinement.
7.1.2 Empty and thoroughly dry the glass apparatus in an oven. Grease the stopcocks and mount the apparatus on a suitable frame.
7.1.3 An alternative method of calibration on the completed assembly to determine the volume, V, utilizes a gas buret procedure. After evacuating the assembled apparatus, including the vacuum gage, to 0.1 mm Hg or less, a calibrated amount of air at atmospheric pressure is allowed to expand into the evacuated apparatus and the resultant pressure recorded. The total apparatus volume may then be simply calculated.
