Sampling - Part 3

Transformer Sampling - Part 3:

Sample Containers

In Part 1 of this series on sampling, we discussed what information is necessary to make a correct diagnosis of the state of your electrical equipment. In Part 2, we discussed some of the issues involved in obtaining a good and representative sample. In Part 3, we will review appropriate sample containers.

The following table lists various sample containers, and highlights their main characteristics. For a more comprehensive list, see ASTM D923 Appendix X2.

Regarding containers for Karl Fischer Moisture Analysis, SDMyers has found that a glass bottle functions as an excellent container for moisture analysis, if all of the following conditions are met:

1. Before sampling, the capped bottle is kept dry by using a desiccant tablet (discarded immediately before sampling).
2. The glass bottle has a metal cap with a Teflon liner.
3. When sampling, the bottle is filled to the very top (if possible), in order to minimize the gas space in the bottle.
4. The KF Moisture test is the first test performed out of the bottle – i.e., the first time the bottle is opened after sampling is for the KF Moisture test.

Using proper sample containers will help ensure that your samples are representative of the actual conditions inside your electrical equipment, enabling proper diagnosis to extend the life of your transformer.