1、Designation:D 3305 94(Reapproved 2005)Standard 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 revisio
2、n.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice covers the sampling of gas from a trans-former gas space or from a gas-collector relay where thevolume of gas available
3、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 should be raised bythe addition of nitrogen gas
4、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 determine the applica-bility of regulatory limita
5、tions prior to use.2.Referenced Documents2.1 ASTM Standards:2D 2759 Practice for Sampling Gas from a TransformerUnder Positive Pressure3.Significance and Use3.1 Gases may be formed in oil-filled electrical equipmentas a result of faults.The type of fault and its severity may oftenbe inferred from th
6、e 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 partition between the gaseous and liquid phases.On t
7、ransformers 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,5-mL,with luer loc termination.4.2 Stopcock,thre
8、e-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 valve and stopcock so gas space gas can flushai
9、r 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 care that gas pressure doesnot eject the plunge
10、r 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 thesyringe.5.7 Close the valve on the gas space.5.8
11、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 of ASTM Committee D27 on ElectricalInsulating Li
12、quids and Gases and is the direct responsibility of SubcommitteeD27.07 on Physical Test.Current edition approved Oct.1,2005.Published November 2005.Originallyapproved in 1974.Last previous edition approved in 1999 as D 3305 94(1999)e1.2For referenced ASTM standards,visit the ASTM website,www.astm.or
13、g,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.ASTM International ta
14、kes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard.Users of this standard are expressly advised that determination of the validity of any such patent rights,and the riskof infringement of such rights,are entirely their own resp
15、onsibility.This standard is subject to revision at any time by the responsible technical 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
16、to ASTM International Headquarters.Your comments will receive careful consideration at a meeting of theresponsible technical committee,which you may attend.If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards,at the address shown below.This standard is copyrighted by ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.Individual reprints(single or multiple copies)of this s
