The Analysis of gases dissolved in electrical insulation oil by gas chromatography- insulation oil proficiency scheme consists on conducting tests for the determination of dissolved gases in insulating oil of transformers, with any laboratory that can do the test, because almost all laboratories are not accredited, being elegible to participate.
The participants must test the samples of electrical transformer oil and verify the quantity of dissolved gases at the samples, expecting the following value:
Hydrogen: 100 – 2000 [ppm];
Oxygen: 1000 – 10000 [ppm];
Nitrogen: 10000 – 100000 [ppm];
Methane (CH4): 100 – 3000 [ppm];
Ethane (C2H6): 300 – 1500 [ppm];
Ethylene (C2H4): 800 – 4000 [ppm];
Acetylene (C2H2): 5 – 50 [ppm];
Carbon monoxide (CO): 100 – 2000 [ppm];
Carbon dioxide (CO2): 2000 – 10000 [ppm].
The participant must do the test according to its routine and to one of test standards, for determination of dissolved gases in electrical transformer insulating oil: ABNT NBR 7070 “amostragem de gases e óleo em transformadores e análise dos gases livres e dissolvidos” and ASTM 3612 Standard Test Method for Analysis of Gases Dissolved in Electrical Insulating Oil by Gas Chromatography.
Qualabor guarantees that the identity of the proficiency testing program participant is confidential and only known by the people involved into the proficiency testing program operation, unless the participant disclaims its confidentiality. Qualabor guarantees that all information given by participants is treated as confidential.
For quantitative testing Qualabor follow the following order for assigned value choice priority:
1) Robust Z – Score with the robust average - In the area of testing there are not clear levels of quality between laboratories for the same test, this way is hard to determine a laboratory with recognition of a higher quality that is accepted by the other participants. The use of an assigned value from a group consensus is the most applicable, In this case determined by the results robust average, which does not require an independent treatment of outliers. To be able to use group consensus with minimal robustness is necessary a group with 4 or more participants. The choice of the z-score method is due to the same being of greater acceptance by the clients and also by difficulties in calculating uncertainty of measurement by the participants, which is not sensitive to this method.
02) Normalized error with a reference value – When it is not possible to have a group with more than 3 participants the assigned value utilized will be a reference value previously validated with participants and always that exist, this value will be taken through an accredited laboratory, and in this case is given priority to the normalized error because the denominator of z score is the program standard deviation which has low robustness because there are few participants.
The activities of Qualabor as proficiency testing provider are done with impartiality and are structured and managed to guarantee the impartiality, Qualabor also guarantee that commercial, financial and other types of pressure will not compromise Qualabor’s impartiality. This is guaranteed through the acknowledgment and agreement term, signed by Qualabor collaborators who affect the quality of proficiency testing.
(Certificate Number: AP-2654, ANSI National Accreditation Board - USA)
Qualabor's QMS is implemented and effectively maintained according ISO/IEC 17043.
EPTIS helps you find a suitable proficiency testing (PT) scheme for your laboratory (a PT scheme is a coherent series of single rounds). For a large number of schemes we have produced data sheets and collected them in the EPTIS database. What is not included in the database is topical information on next PT rounds. When is the next round, and what is the matrix material this time? This information is too dynamic as to be included in the database. But you can find such details for a selection of schemes in our PT calendar.
At present, a listing on the database is only open to PT providers from countries that are covered by our so-called coordinators. They check the plausibility of the data sheet submissions and decide on their publication. They speak the language and are ideally familiar with local PT providers and cultural peculiarities. This helps to safeguard a reasonable level of database quality. There is no cost for PT providers who follow this basic mechanism.