ASTM D923 standard practices for sampling electrical insulating liquids
SAMPLING DEVICES
6. Application
6.1 Devices suitable for withdrawing samples of liquid from containers, electrical equipment, cable feeders, and cable joints are shown in Figs. 1-5.
6.2 Dip Type or Drum Thief - The device shown in Fig. 1 is used for taking bottom samples from drums, storage tanks, and small de-energized electrical equipment, that are to be subjected to routine tests. It is not recommended for use under the following conditions:
6.2.1 When the samples are to be subjected to referee tests,
6.2.2 When the relative humidity of the atmosphere exceeds 50 %,
6.2.3 When the samples are to be tested for dissipation factor, resistivity, or moisture content, and
6.2.4 When the viscosity of the liquid to be sampled exceeds 2.28 x 10(-5) m2/5 (21 cSt) at 40°C.
6.3 Pressure Type - The device shown in Fig. 2 and Fig. 3 is intended primarily for sampling drums of high-viscosity liquids. However, it is particularly suitable for obtaining samples of all electrical insulating liquids in drums where it is desired that all contact of the sample with the atmosphere is eliminated. When possible, this device should be used for obtaining samples from drums when these samples are to be subjected to referee tests.
6.4 Tank Car Type - The device shown in Fig. 4 is used for taking either top, middle, or bottom samples from containers of large capacity such as tank cars, tank trucks, and large storage tanks not provided with a sampling-test nipple. This device is not recommended for use under the conditions described in 6.2.1 through 6.2.4.
6.5 Manifold - The device shown in Fig. 5 is used for taking samples from low-pressure oil-filled cable feeders with the use of vacuum and either dry carbon dioxide gas or dry nitrogen gas. Its use is recommended when high relative humidity conditions exist and it is desired to take the samples through a closed system.
6.6 Electrical Equipment Sampling Outlet or Valve, used for taking top or bottom samples from energized or de-energized electrical apparatus. This device is especially suitable when collecting samples in a glass jar, metal can, or other suitable containers as described in Section 9.
7. Construction
7.1 The construction of each of the devices shown in Figs. 1-5 is described in the Annex.
8. Storage
8.1 When not in use, clean sampling devices such as shown in Figs. 1-5 as described in 13.1, Sections 14 and 15, respectively, and keep at all times in a vertical position in a dry, dust-free cabinet or a clean sealed plastic bag. Provide the cabinet with a rack having a suitable drainage receptacle at the base.
8.2 When the sampling device shown in Fig. 5 is not in use, store in a room having low humidity.
