1、Designation: E 576 88 (Reapproved 1999)e1Standard Test Method forFrost Point of Sealed Insulating Glass Units in the VerticalPosition1This 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
2、revision, the year 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.e1NOTEKeywords were added
3、in October 1999.1. Scope1.1 This test method describes a field or laboratory proce-dure for determining the frost point within the air space(s) ofsealed insulating glass units, and establishes the criteria fordetermining whether that point is below or above a given orspecified temperature.1.2 This t
4、est method also describes the apparatus to be usedfor these 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 determin
5、e the applica-bility of regulatory limitations prior to use. For specific hazardstatements, see Notes 2 and 3.2. Referenced Documents2.1 ASTM Standards:C 1036 Specification for Flat Glass2E77 Test Method for Inspection and Verification of Ther-mometers3E 774 Specification for Sealed Insulating Glass
6、 Units43. Terminology3.1 frost pointthe temperature at which visible frostbegins to deposit on the lower air space glass surface of asealed insulating glass unit in contact with the measuringsurface of the frost point apparatus.3.2 frost statethe case where the frost point of a sealedinsulating glas
7、s unit is above the test temperature specified bythe purchaser or user.3.3 no-frost statethe case where the frost point of a sealedinsulating glass unit is below the temperature specified by thepurchaser or user.4. Summary of Test Method4.1 This test method is conducted by the use of a specialappara
8、tus, consisting basically of two chilled cylindrical metalblocks positioned one 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 distan
9、cebetween it and the lower metal block which is maintained atapproximately 78C (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 determin
10、e atwhat temperature frost appears on the corresponding lower airspace glass surface.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
11、or simulated weather conditions. Where the glazingconditions and the 24-h history are different or changed fromprevious conditions, the frost point may not be comparable toa previous measurement.5.2 This test method is applicable for the uncoated orunfilmed clear (transparent) glass pane of sealed i
12、nsulatingglass units. If this apparatus is used with coated or filmed glasspane, the coating or film on the surface of glass pane may bedamaged.1This test method is under the jurisdiction of the ASTM Committee E-6 onPerformance of Buildings and is the direct responsibility of Subcommittee E06.22on D
13、urability Performance of Building Constructions.Current edition approved March 25, 1988. Published September 1988. Originallypublished as E 576 76. Last previous edition E 576 79.2Annual Book of ASTM Standards, Vol 15.02.3Annual Book of ASTM Standards, Vol 14.03.4Annual Book of ASTM Standards, Vol 0
14、4.11.1Copyright 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 point apparatus incontact with the glass if the insulating glass unit is not in thetr
15、ue vertical position.6. Apparatus6.1 Test Apparatus5(see Fig. 1), consisting of upper andlower cylindrical metal blocks, with a thermocouple, bimetallicthermometer, or other suitable temperature sensors beinginserted in the upper block; a control ring; and an insulatedcontainment cylinder fitted wit
16、h 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 ground or lapped finish, and when placed incontact with the glass test
17、 specimen, forms the frost 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). Because the solid metal blocks arehighly conductive, the temperature
18、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 thusreadily adjusted to the desired temperature while in contact5Available from Denni
19、s Industries, 20032 Waynegarden Court, Germantown,MD 20874.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 elbow5 spacer 16 tub
20、e, 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 Point ApparatusE 576 88
21、(1999)e12with the test specimen. The circular measuring surface diam-eter specified is suitable for frost point measurement of glassup to 6.0 mm (14 in.) thick.6.1.1 Upper and Lower Blocks, aluminum alloy that may beanodized, conforming to the dimensions shown in Fig. 1. Otherparts of the apparatus
22、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 anaccuracy of 60.5C (61F) over the full scale. A suggestedcalibration of the
23、bimetallic thermometer is described inAppendix X1.6.2 Vertical Attachment Fixture5(see Fig. 2), consisting of atwin-grip vacuum cup holder, two parallel guide rods, twospring posts, and two clamping springs. The vacuum cup ismade of rubber. When the vertical attachment fixture is placedon the surfac
24、e 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 Gage6(see Fig. 3).7. Test Unit7.1 The sealed insulating glass unit to be tested should havea clea
25、r 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 temperature of 24 6 3C (7565F) for not less than 24 h prior to the testing.8.2 C
26、ondition 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 actual in-service condi-tions, record or obtain the ambient temperatures of
27、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 point of the unit from the reportedtemperature6A device found suitable for this purp
28、ose, U.S. Patent No. 3320849, is availablefrom J. R. Cumberland, Precision Optics, 4505 Beech Rd., Washington, DC 20031.Parts ListPart No. Nomenclature1 rubber vacuum cup2 guide rod3 clamping spring4 vacuum hand lever5 hand grip6 spring postFIG. 2 Vertical AttachmentE 576 88 (1999)e13history to that
29、 implied in-service level of the unit. However, the tempera-ture history will provide a valuable basis for evaluating the in-service leveland life of the unit in the future.9. Procedure9.1 Preparation of Frost-Point Apparatus:9.1.1 Disassemble the apparatus by removing the dry icecontainer and retai
30、ner spring assembly. Carefully clean themeasuring surface with a soft cloth or paper. 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
31、distance between front and rear metalblocks is about 13 mm (0.5 in.). Invert the apparatus onto a softcloth, or a suitable mounting bracket.9.1.3 Spray alcohol or acetone (WarningSee Note 2)onthe fin of the dry ice container to ensure good contact with thedry ice. Compactly charge the container with
32、 the crushed orpulverized dry ice up to the “full” mark. Compress the dry icewith the spring assembly and lock the cover lid.NOTE 2Warning: Both alcohol and acetone are flammable.9.1.4 Turn the apparatus to an upright position. Allowsufficient time for the temperature of the rear metal block toappro
33、ach near that of the dry ice temperature.9.2 Recharging of Frost Point ApparatusDuring the testprocedure, replenish the supply of dry ice whenever it becomesdepleted by inverting the apparatus onto a soft cloth, openingthe cover lid, taking out the retainer spring assembly, andrepeating steps 9.1.3
34、and 9.1.4.9.3 Determination of Frost State or No-Frost State:9.3.1 Charge the frost-point apparatus with 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 a
35、t a 45 angle.9.3.2.2 Observe the reflection in the glass.9.3.2.3 Note where the long line superimposes the shortline.9.3.2.4 Read the minimum thickness of the glass above.9.3.3 Place the frost-point apparatus on top of the guide rodsof the vertical attachment fixture, facing the measuring surfaceof
36、the frost-point apparatus toward the rubber vacuum cup, andslide both guide fins of the frost-point apparatus in between theguide rods from the rear end.9.3.4 Hook each clamping spring to the hooks of thefrost-point apparatus.9.3.5 Clean the exterior glass surface where the frost-pointapparatus and
37、the vertical attachment fixtures are to be placed.Measure the frost point within an area at least 250 mm (10 in.)away from the spacer or at the center of the unit. Examine theinterior air space glass surface in the region where dew or frostis to be deposited, to be aware of any dirt or other foreign
38、particles that might be mistaken for frost. However, a smallforeign particle on the interior air space glass surface may behelpful in focusing on the surface where the frost is to bedeposited.Avoid the area where sunlight strikes directly on theunit or shade it from direct sunlight.9.3.6 Release bot
39、h vacuum hand levers of the verticalattachment fixture.9.3.7 Clean the surfaces of the rubber vacuum cups, and themeasuring surface and front surface of the frost-point appara-tus. If there are any water vapor or frost deposits on themeasuring surface of the frost-point apparatus, clean themeasuring
40、 surface by wetting with alcohol (WarningSeeNote 3). If the measuring surface is heavily scratched, the frontmetal block should be replaced or repaired. If the dew or frostdeposit can be checked from the other side of the unit asdescribed in 9.3.15, a piece of silver-colored aluminizedpolyester film
41、5(with a highly reflective surface, not thickerthan 0.08 mm (0.003 in.), and 25 mm (1 in.) in diameter, or 25by 25 mm (1 by 1 in.) can be placed on the measuring surfaceby wetting both surfaces with alcohol.NOTE 3Warning: Alcohol is flammable.9.3.8 To provide better thermal contact, wet the measurin
42、gsurface of the frost point apparatus and exterior glass surfacewhere it is to be contacted with alcohol (see Note 3).(a) Gage (b) Gage in UseFIG. 3 Glass Thickness GageE 576 88 (1999)e149.3.9 Hold the hand grip of the vertical attachment fixturewith one hand in a level position. Contact the measuri
43、ngsurface against the wetted glass surface and push the verticalattachment so that both rubber vacuum cups touch flatlyagainst the glass surface (see Fig. 4).9.3.10 Slowly flip the vacuum hand levers to a lockingposition so that the vertical attachment fixture is held firmlyagainst the glass surface
44、 of the unit. If a vacuum cup does nothold the vacuum properly, release the vacuum hand lever andflip it again while applying a little more force. Make sure thatthe measuring surface and front surface of the frost-pointapparatus are flush with the glass surface. If it is not flush withthe glass surf
45、ace, adjust it by either increasing the tension ofthe clamping springs or adjusting the guide rod. If needed,shim the guide rod.NOTE 4Warning: Take care that the vertical attachment fixture doesnot fall off during the measurement.9.3.11 Wipe off the excessive alcohol running down theglass surface fr
46、om the measuring surface before it reaches theglazing materials.9.3.12 Slowly reduce the air gap distance 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 b
47、e checked for frost and stabilize it by fineadjustment of the control ring. Temperature fluctuation 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
48、 (185.0 (316)46.0 (14)5NOTE 5See 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 better
49、detection of frost deposit, if needed. If the other side of the unitis not accessible, unhook the clamping spring and slide out thefrost point apparatus far enough to examine the interior airspace glass surface. Then, quickly examine the interior airspace glass surface for frost deposit. If the frost forms or watervapor condenses on the exterior glass surface where themeasuring surface is contacted, wet the exterior glass surfacewith a small amount of alcohol.9.3.16 If a clearly visible frost deposit appears on theinterior air space glass sur
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