ASTM_D_5423_-_14.pdf

Designation:D542314Standard Specification forForced-Convection Laboratory Ovens for Evaluation ofElectrical Insulation1This standard is issued under the fixed designation D5423;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This specification covers forced-convection ventilatedelectrically-heated ovens,operating over all or part of thetemperature range from 20C above the ambient temperature to500C,and used for thermal endurance evaluation of electricalinsulating materials.1.2 The specification requirements for Type I ovens arebased on IEC Publication 216-4-1,and are technically identicalto it.The requirements for Type II ovens are essentiallyidentical to the requirements of Specification D2436.Thisspecification and an associated test method,D5374,havereplaced Specification D2436.1.3 While the ovens covered by this specification areintended primarily for thermal endurance evaluation,they canalso be used wherever their characteristics make them suitablefor other applications.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 limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D2436 Specification for Forced-Convection Laboratory Ov-ens for Electrical Insulation(Withdrawn 1994)3D5374 Test Methods for Forced-Convection Laboratory Ov-ens for Evaluation of Electrical Insulation2.2 Other Document:IEC Publication 216-4-1 Guide for the Determination ofThermal Endurance Properties of Electrical InsulatingMaterials,Part4AgingOvens,Section1Single-Chamber Ovens43.Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 rate of ventilation,nthe number of air changes perhour in the oven chamber.3.1.2 set temperature,nthe average of all of the measuredtemperatures within the oven,averaged over the period of anycyclic temperature variation that may occur.3.1.2.1 DiscussionThis is the actual operating temperatureof the oven.3.1.3 temperature fluctuation,ntemperature differences atone point in the oven over a period of time.3.1.3.1 DiscussionThis property depends upon the sensi-tivity and type(on/off or proportional)of control used and theheater mass in relation to surface area.3.1.4 temperature gradient,nthe maximum temperaturedifference at one time between different points in the ovenchamber.3.1.4.1 DiscussionThis property depends on such factorsas uniformity of heater temperature,heater distribution aboutthe oven,and air flow patterns within the oven.3.1.5 temperature variation,ntemperature differenceswith time and location due to the combination of temperaturegradient and temperature fluctuation.3.1.6 thermal lag time,nthe time required for a definedspecimen to reach a specified temperature(or range of tem-perature).3.1.6.1 DiscussionThis property is largely dependentupon the rate of air circulation within the oven.In IEC 216-4-1,this term is called“time constant.”3.1.7 time constant,nSee thermal lag time.1This specification is under the jurisdiction of ASTM Committee D09 onElectrical and Electronic Insulating Materials and is the direct responsibility ofSubcommittee D09.17 on Thermal Characteristics.Current edition approved April 1,2014.Published May 2014.Originallyapproved in 1993.Last previous edition approved in 2005 as D5423 93(2004),which was withdrawn in January 2014 and reinstated in April 2014.(1999).DOI:10.1520/D5423-14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.Classification4.1 Type IOvens with rate of ventilation of 5 to 20 airchanges per hour.4.2 Type IIOvens with rate of ventilation of 100 to 200 airchanges per hour.5.Test Methods5.1 Determine the properties specified in Section 6 usingTest Methods D5374.6.Performance Requirements6.1 Rate of VentilationThe rate of ventilation at 100C andat the maximum temperature at which the oven is used shall be:6.1.1 For Type I ovens,5 to 20 air changes per hour,6.1.2 For Type II ovens,100 to 200 air changes per hour.NOTE1Past experience in the United States has been to specify 100to 200 air changes per hour,as required for Type II ovens.However,international practice,as defined in IEC Publication 216-4-1,has bee