ASTM-D7150:13(R2020) pdf free download – Standard Test Method for the Determination of Gassing Characteristics of Insulating Liquids Under Thermal Stress.
7. Method A
7.1 If the sample has visible particles, filter 225 mL of insulating liquid through a 1 or I .2-im filter. Discard the first 25 mL. Collect the remainder in a flask that has been cleaned, rinsed with distilled water and dried for 4 h at 1(X) ± 5°C. Flasks that have been prepared beforehand are acceptable as long as all openings have been covered with aluminum foil. Alternatively, remove the plunger from a glass syringe and secure the tip of the barrel with a metal female luer-to-closedend adapter. Place the barrel in a vertical position so that the large opening of the barrel is facing up. Place 25 mL of insulating liquid in a 30 rnL syringe or 40 mL of oil in a 50 mL syringe. For flasks, use 100 mL.
7.2 Sparge enough of the filtered insulating liquid to conduct the testing with dry air for 30 ± 3 mm. Sparge the air through the liquid at an approximate flow rate of 200 mL per minute. Typical setups are shown in Fig. I and Fig. 2.
7.3 If not already prepared in the syringes, immediately fill two (2) glass syringes (either 30- or 50-mL) with the sparged insulating liquid (25 mL in the 30-mL syringe; 40 rnL in the 50-mL syringe). Make sure the syringe is filled with enough test specimen to conduct a dissolved gas-in-oil analysis. The barrel and plunger of each glass syringe must be well-fitted to avoid air ingress at the junction of the plunger and barrel seal as the test specimen is being heated during the test procedure.
7.4 Immediately remove any trapped bubbles from the syringe as described in Practice D36 12 and seal the syringe with a female-luer-to-closed-end adapter if not already done so. Do not use plastic stopcocks as they tend to leak and melt during the heating phase of the procedure.
7.5 Sparge more insulating liquid as described in 7.1 through 7.2, but with dry nitrogen for 30 ± 3 mm. The nitrogen is sparged through the insulating liquid at an approximate flow rate of 200 mL per minute.
7.6 Repeat the procedures listed in 7.3 and 7.4 for the nitrogen-sparged insulating liquid.
7.7 Place the syringes with the test specimens laying down in the oven with the leur fitting slightly above horizontal. Heat all the test specimens at 120 2°C for 164 h 15 mm. Remove the test specimens from the oven, allow to cool for at least I h.
7.8 After the test specimens have been allowed to cool (Note I), remove the female-luer-to-closed-end adapter and replace with normal stopcocks. Expel a small amount of oil (2-5 niL) from the stopcock to remove any air that may have entered into the syringe when changing out the female-luer-toclosed-end adapter.
Nom 1—Periodically check for air ingress during the cooling of the syringe. In those cases where it is visible, it is advisable to perform the lest again.
7.9 Perform dissolved gas-in-oil analysis (Note 2) on all four test specimens according to Test Method D36 12 or IEC 60599. Whichever Test Method D36 12 method is employed (A. B, or C) or IEC 60599. the following minimum detection limits must be met.