1、Designation:D 3305 94(Reapproved 1999)e1Standard Practice forSampling Small Gas Volume in a Transformer1This standard is issued under the fixed designation D 3305;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revis
2、ion.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.e1NOTEEditorial changes were made in March 1999.1.Scope1.1 This practice is used for sampling gas from a trans-former gas space or from a gas-c
3、ollector relay where thevolume of gas available is small and will not permit the use ofPractice D 2759.1.2 This practice covers sampling,using a gas-tight syringeas the sampling apparatus and container.1.3 If the apparatus to be sampled is found to be under anegative pressure,the apparatus pressure
4、should be raised bythe addition of nitrogen gas until a positive pressure isobtained.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and d
5、etermine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:D 2759 Practice for Sampling Gas from a TransformerUnder Positive Pressure23.Significance and Use3.1 Gases may be formed in oil-filled electrical equipmentas a result of faults.The type of fau
6、lt and its severity may oftenbe inferred from the composition of the gases.3.2 Gas samples are taken from transformer gas spaces orfrom gas-collector relays in order that the composition of thegas sample may be determined.3.3 In nitrogen-blanketed transformers,the gases generatedby a fault will part
7、ition between the gaseous and liquid phases.On transformers with gas-collector relays,gas in the form ofbubbles may collect in a gas-collector relay and provide ameans to obtain a gas sample for analysis.3.4 Do not draw samples from an energized instrumenttransformer.4.Apparatus4.1 Syringe,gastight,
8、5-mL,with luer loc termination.4.2 Stopcock,three-way,plastic.4.3 Length of PTFE Tubing,18in.inside diameter.5.Procedure5.1 Connect the plastic stopcock to the plastic tubing.Connect the other end of tubing to a suitable valved entrance tothe transformer gas space or gas-collector relay.5.2 Open the
9、 valve and stopcock so gas space gas can flushair from valve,tubing and stopcock.(The stopcock handlepoints to the closed port,leaving the other two ports in opencommunication.)5.3 Connect syringe to the stopcock.5.4 Turn the stopcock handle to allow gas from the gasspace to enter the syringe,taking
10、 care that gas pressure doesnot eject the plunger completely.5.5 Turn the stopcock so gas can be expelled from thesyringe through the exhaust port of stopcock by pushingplunger home.5.6 Open the stopcock to connect gas space to syringe andfill syringe.Close the stopcock by turning handle toward thes
11、yringe.5.7 Close the valve on the gas space.5.8 Remove the plastic tubing from the valve and stopcock,leaving the stopcock on the syringe.5.9 Label the sample,package carefully,and transport tolaboratory for analysis.6.Keywords6.1 gas;sampling gas;transformer1This practice is under the jurisdiction
12、of ASTM Committee D-27 on ElectricalInsulating Liquids and Gases and is the direct responsibility of SubcommitteeD27.07 on Physical Tests.Current edition approved July 15,1994.Published September 1994.Originallypublished as D 3305 74.Last previous edition D 3305 84(1989).2Annual Book of ASTM Standar
13、ds,Vol 10.03.1AMERICAN SOCIETY FOR TESTING AND MATERIALS100 Barr Harbor Dr.,West Conshohocken,PA 19428Reprinted from the Annual Book of ASTM Standards.Copyright ASTMThe American Society for Testing and Materials takes no position respecting the validity of any patent rights asserted in connectionwit
14、h any item mentioned in this standard.Users of this standard are expressly advised that determination of the validity of any suchpatent rights,and the risk of infringement of such rights,are entirely their own responsibility.This standard is subject to revision at any time by the responsible technic
15、al committee and must be reviewed every five years andif not revised,either reapproved or withdrawn.Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM Headquarters.Your comments will receive careful consideration at a meeting of the responsibletechnical committee,which you may attend.If you feel that your comments have not received a fair hearing you should make yourviews known to the ASTM Committee on Standards,100 Barr Harbor Drive,West Conshohocken,PA 19428.D 33052
