1、Designation: E 576 08Standard Test Method forFrost/Dew Point of Sealed Insulating Glass Units in theVertical Position1This standard is issued under the fixed designation E 576; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the ye
2、ar of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test method describes a f
3、ield or laboratory proce-dure for determining the frost/dew point within the air space(s)of sealed insulating glass units and establishes the criteria fordetermining whether that point is below or above a given orspecified temperature.1.2 This test method also describes the apparatus to be usedfor t
4、hese determinations.1.3 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
5、 use. For specific hazardstatements, see 9.1.3 and 9.3.7.2. Referenced Documents2.1 ASTM Standards:2C 1036 Specification for Flat GlassE77 Test Method for Inspection and Verification of Ther-mometersE 631 Terminology of Building ConstructionsE 774 Specification for the Classification of the Durabili
6、tyof Sealed Insulating Glass Units33. Terminology3.1 DefinitionsFor definitions of general terms used inthis test method, refer to Terminology E 631.3.2 Definitions of Terms Specific to This Standard:3.2.1 frost statethe case where the frost/dew point of asealed insulating glass unit is above the te
7、st temperaturespecified by the purchaser or user.3.2.2 frost/dew pointthe temperature at which water, or-ganic vapor, or other chemicals begin to appear on the interiorglass surface of a sealed insulating glass unit in contact withthe measuring surface of the frost/dew-point apparatus.3.2.3 no-frost
8、 statethe case where the frost/dew point of asealed insulating glass unit is below the temperature specifiedby the purchaser or user.4. Summary of Test Method4.1 This test method is conducted by the use of a specialapparatus, consisting basically of two chilled cylindrical metalblocks positioned one
9、 over the other and separated by a gap ofcontrollable distance. The upper block has an exposed flatcircular surface, 25 mm (1 in.) in diameter, and can be chilledto far below the ice point by regulating the air gap distancebetween it and the lower metal block which is maintained atapproximately 78C
10、(109F) by dry ice. The test specimenis placed in contact with this chilled flat circular surface of theupper block for specified short periods of time, with the metalsurface at successively lower temperatures, to determine atwhat temperature frost appears on the corresponding lower airspace glass su
11、rface.5. Significance and Use5.1 This test method is suitable for use under actual orsimulated in-service conditions; that is, one side of the unit isexposed to room temperature, while the other side is exposedto natural or simulated weather conditions. Where the glazingconditions and the 24-h histo
12、ry are different or changed fromprevious conditions, the frost/dew point may not be compa-rable to a previous measurement.5.2 This test method is applicable for the uncoated orunfilmed clear (transparent) glass pane of sealed insulatingglass units. If this apparatus is used with coated or filmed gla
13、sspane, the coating or film on the surface of glass pane may bedamaged.1This test method is under the jurisdiction of ASTM Committee E06 onPerformance of Buildings and is the direct responsibility of Subcommittee E06.22on Durability Performance of Building Constructions.Current edition approved Apri
14、l 1, 2008. Published May 2008. Originallyapproved in 1976. Last previous edition approved in 1999 as E 576 88 (1999)e1.2For 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
15、to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.3 This test method may require minor modifications tokeep the measuring surface of the frost/dew-point apparatus i
16、ncontact with the glass if the insulating glass unit is not in thetrue vertical position.6. Apparatus6.1 Test Apparatus4(see Fig. 1); consisting of upper andlower cylindrical metal blocks with a thermocouple, bimetallicthermometer, or other suitable temperature sensors beinginserted in the upper blo
17、ck; a control ring; and an insulatedcontainment cylinder fitted with a retainer spring assembly.The two metal blocks are separated by a small air gap, thedistance of which can be regulated by the control ring. Theexposed flat circular surface of the upper block is 25 mm (1 in.)in diameter, has a gro
18、und or lapped finish, and when placed incontact with the glass test specimen, forms the frost/dew pointmeasuring surface. The lower block is chilled by a dry ice packkept in contact with it by the retainer spring assembly,maintaining it at a temperature near to that of sublimating dryice (78C (109F)
19、. Because the solid metal blocks arehighly conductive, the temperature of each is virtually uniform.Use of the control ring adjusts the air gap distance between thetwo blocks to give the desired thermal resistance across the airgap. The circular measuring surface of the upper block is thus4The sole
20、source of supply of the apparatus known to the committee at this timeis Dennis Industries, 20032 Waynegarden Court, Germantown, MD 20874, http:/. If you are aware of alternative suppliers, please provide thisinformation to ASTM International Headquarters. Your comments will receivecareful considerat
21、ion at a meeting of the responsible technical committee,1whichyou may attend.Parts ListPart No. Nomenclature Part No. Nomenclature1 front metal block 12 supporting ring, bottom ofinner tube2 rear metal block 13 control ring3 top cover 14 cover lid, inner tube4 supporting plate, front metalblock15 el
22、bow5 spacer 16 tube, nylon6 spring front metal block 17 main spring7 supporting plate, top ofinner tube18 spacer8 outer tube 19 bearing9 inner tube 20 bimetallic dial thermometer10 disk, dry ice pushing 21 dial indicator11 clamp, dial gage 22 heat source blockFIG. 1 Schematic Diagram of Frost/Dew-Po
23、int ApparatusE576082readily adjusted to the desired temperature while in contactwith the test specimen. The circular measuring surface diam-eter specified is suitable for frost/dew point measurement ofglass up to 6.0 mm (14 in.) thick.6.1.1 Upper and Lower Blocks, aluminum alloy that may beanodized,
24、 conforming to the dimensions shown in Fig. 1. Otherparts of the apparatus may be fabricated from any appropriatematerials.6.1.2 Calibrated Temperature-Measuring Device; such as athermocouple, thermistor, or bimetallic thermometer; having asuitable range graduated in 1C (2F) or smaller units; and an
25、accuracy of 60.5C (61F) over the full scale. A suggestedcalibration of the bimetallic thermometer is described inAppendix X1.6.2 Vertical Attachment Fixture4(see Fig. 2), consisting of atwin-grip vacuum cup holder, two parallel guide rods, twospring posts, and two clamping springs. The vacuum cup is
26、made of rubber. When the vertical attachment fixture is placedon the surface of clean glass and the vacuum hand lever ispushed down, the vertical attachment fixture becomes firmlyattached to the glass surface. Other equivalent attachmentfixtures may be used.6.3 Glass Thickness Gage (see Fig. 3).7. T
27、est Unit7.1 The sealed insulating glass unit to be tested should havea clear glass pane (see 5.2) in contact with the measuring sideof the test apparatus and shall be positioned vertically.8. Conditioning8.1 Condition the unit to be tested at room temperature onboth unit sides by exposing to a tempe
28、rature of 24 6 3C(75 6 5F) for not less than 24 h prior to the testing.8.2 Condition the unit to be tested under simulated in-service conditions by exposing to temperatures within 63C(65F) of the desired simulated conditions for not less than 24h prior to testing.8.3 For the unit to be tested under
29、actual in-service condi-tions, record or obtain the ambient temperatures of both sidesof the unit at the start and end of a particular measuring period,and the 24-h temperature history prior to testing.NOTE 1At the present time, there is insufficient information tocompare the measured frost/dew poin
30、t of the unit from the reportedtemperature history to that implied in-service level of the unit. However,the temperature history will provide a valuable basis for evaluating thein-service level and life of the unit in the future.Parts ListPart No. Nomenclature1 rubber vacuum cup2 guide rod3 clamping
31、 spring4 vacuum hand lever5 hand grip6 spring postFIG. 2 Vertical AttachmentE5760839. Procedure9.1 Preparation of Frost/Dew-Point Apparatus:9.1.1 Disassemble the apparatus by removing the dry icecontainer and retainer spring assembly. Carefully clean themeasuring surface with a soft cloth or paper.
32、Do not scratch themeasuring surface. Wipe and clean the apparatus thoroughly ifany moisture has condensed on the surfaces and walls.9.1.2 Assemble the dry ice container and turn the controlring so that the air gap distance between front and rear metalblocks is about 13 mm (0.5 in.). Invert the appar
33、atus onto a softcloth or a suitable mounting bracket.9.1.3 Spray alcohol or acetone (WarningBoth alcoholand acetone are flammable.) on the fin of the dry ice containerto ensure good contact with the dry ice. Compactly charge thecontainer with the crushed or pulverized dry ice up to the “full”mark. C
34、ompress the dry ice with the spring assembly and lockthe cover lid.9.1.4 Turn the apparatus to an upright position. Allowsufficient time for the temperature of the rear metal block toapproach near that of the dry ice temperature.9.2 Recharging of Frost/Dew-Point ApparatusDuring thetest procedure, re
35、plenish the supply of dry ice whenever itbecomes depleted by inverting the apparatus onto a soft cloth,opening the cover lid, taking out the retainer spring assembly,and repeating steps 9.1.3 and 9.1.4.9.3 Determination of Frost State or No-Frost State:9.3.1 Charge the frost/dew-point apparatus with
36、 dry ice asdescribed in 9.1 or 9.2.9.3.2 Measure the thickness of glass in the measuring sideas follows:9.3.2.1 Place the long side of the glass thickness gage (seeFig. 3) against the glass pane at a 45 angle.9.3.2.2 Observe the reflection in the glass.9.3.2.3 Note where the long line superimposes t
37、he shortline.9.3.2.4 Read the minimum thickness of the glass above.9.3.3 Place the frost/dew-point apparatus on top of the guiderods of the vertical attachment fixture, facing the measuringsurface of the frost/dew-point apparatus toward the rubbervacuum cup, and slide both guide fins of the frost/de
38、w-pointapparatus in between the guide rods from the rear end.9.3.4 Hook each clamping spring to the hooks of thefrost/dew-point apparatus.9.3.5 Clean the exterior glass surface where the frost/dew-point apparatus and the vertical attachment fixtures are to beplaced. Measure the frost/dew point withi
39、n an area at least 250mm (10 in.) away from the spacer or at the center of the unit.Examine the interior air space glass surface in the region,where dew or frost is to be deposited, to be aware of any dirtor other foreign particles that might be mistaken for frost.However, a small foreign particle o
40、n the interior air space glasssurface may be helpful in focusing on the surface where thefrost is to be deposited. Avoid the area where sunlight strikesdirectly on the unit or shade it from direct sunlight.9.3.6 Release both vacuum hand levers of the verticalattachment fixture.9.3.7 Clean the surfac
41、es of the rubber vacuum cups, and themeasuring surface and front surface of the frost/dew-pointapparatus. If there are any water vapor or frost deposits on themeasuring surface of the frost/dew-point apparatus, clean themeasuring surface by wetting with alcohol (WarningAlcohol is flammable.). If the
42、 measuring surface is heavilyscratched, the front metal block should be replaced or repaired.If the dew or frost deposit can be checked from the other sideof the unit as described in 9.3.15, a piece of silver-coloredaluminized polyester film with a highly reflective surface, notthicker than 0.08 mm
43、(0.003 in.), and 25 mm (1 in.) indiameter, or 25 by 25 mm (1 by 1 in.) can be placed on themeasuring surface by wetting both surfaces with alcohol.9.3.8 To provide better thermal contact, wet the measuringsurface of the frost/dew-point apparatus and exterior glasssurface where it is to be contacted
44、with alcohol (WarningSee 9.3.7).9.3.9 Hold the hand grip of the vertical attachment fixturewith one hand in a level position. Contact the measuringsurface against the wetted glass surface and push the verticalattachment so that both rubber vacuum cups touch flatlyagainst the glass surface (see Fig.
45、4).(a) Gage (b) Gage in UseFIG. 3 Glass Thickness GageE5760849.3.10 Slowly flip the vacuum hand levers to a lockingposition so that the vertical attachment fixture is held firmlyagainst the glass surface of the unit. If a vacuum cup does nothold the vacuum properly, release the vacuum hand lever and
46、flip it again while applying a little more force. Make sure thatthe measuring surface and front surface of the frost/dew-pointapparatus are flush with the glass surface. If it is not flush withthe glass surface, adjust it by either increasing the tension ofthe clamping springs or adjusting the guide
47、 rod. If needed,shim the guide rod. (WarningTake care that the verticalattachment fixture does not fall off during the measurement.)9.3.11 Wipe off the excessive alcohol running down theglass surface from the measuring surface before it reaches theglazing materials.9.3.12 Slowly reduce the air gap d
48、istance between front andrear metal blocks by turning the control ring while watchingthe temperature of the front metal block.9.3.13 Bring the temperature of the front metal block to thetemperature to be checked for frost and stabilize it by fineadjustment of the control ring. Temperature fluctuatio
49、n shouldnot exceed 61C (62F).9.3.14 Maintain the stabilized temperature for a minimumtime duration as follows:Glass Thickness Designation,mm (in.)Stabilized TemperatureDuration,minimum, min2.5 (332)33.0 (185.0 (316)46.0 (14)5NOTE 2See Specification C 1036.9.3.15 If the other side of the unit is accessible, clean theexterior glass surface and examine the interior air space glasssurface in contact with the measuring surface. Illuminate theinterior air space glass surface with a flashlight for betterdetection of frost deposit, if n
