1、Designation: E 546 08An American National StandardStandard Test Method forFrost/Dew Point of Sealed Insulating Glass Units1This standard is issued under the fixed designation E 546; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, t
2、he 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.1. Scope1.1 This test method describe
3、s a laboratory procedure fordetermining the frost/dew 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 test method also describes the apparatus to be usedfor these
4、determinations.1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.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 t
5、o establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specific hazardstatements, see 9.1.3.2. Referenced Documents2.1 ASTM Standards:2C 1036 Specification for Flat GlassE77 Test Method for Inspection and Verification of Ther
6、-mometersE 576 Test Method for Frost/Dew Point of Sealed InsulatingGlass Units in the Vertical PositionE 631 Terminology of Building Constructions3. Terminology3.1 DefinitionsFor definitions of general terms used inthis test method, refer to Terminology E 631.3.2 Definitions of Terms Specific to Thi
7、s Standard:3.2.1 frost statethe case where the frost/dew point of asealed insulating glass unit is above the test temperaturespecified by the purchaser or user.3.2.2 frost/dew point, nthe temperature at which water,organic vapor, or other chemicals begin to appear on theinterior glass surface of a s
8、ealed insulating glass unit in contactwith the measuring surface of the frost/dew-point apparatus.3.2.3 no-frost 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 conduc
9、ted by the use of a specialapparatus, 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
10、 by regulating the air-gap distancebetween 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 successivel
11、y lower temperatures, to determine atwhat temperature frost appears on the corresponding lower airspace glass surface.5. Significance and Use5.1 This test method and the apparatus described are in-tended primarily for sealed insulating glass units positionedhorizontally. If the procedure is applied
12、to such units in otherthan a horizontal position, the results may not be comparable tothose obtained by this procedure.NOTE 1A similar method is Test Method E 576.6. Apparatus6.1 Test Apparatus3(see Fig. 1), consisting of upper andlower cylindrical metal blocks with a thermocouple, bimetallicthermom
13、eter, or other suitable temperature sensors beinginserted in the upper block; a control ring; and an insulated1This 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 Cons
14、tructions.Current edition approved April 1, 2008. Published May 2008. Originallyapproved in 1975. Last previous edition approved in 1999 as E 546 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 A
15、STMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The sole 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, plea
16、se provide thisinformation to ASTM International Headquarters. Your comments will receivecareful consideration at a meeting of the responsible technical committee,1whichyou may attend.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.c
17、ontainment 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 ground or lapped finish; and, when place
18、d 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). Because the solid metal blocks are
19、highly 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 thusreadily adjusted to the desired temperature wh
20、ile 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 Metal Blocks, aluminum alloy thatmay be anodized, conforming to the dimensions shown in Fig.1. Other parts of
21、 the apparatus may be fabricated from anyappropriate materials.6.1.2 Calibrated Temperature-Measuring Device; such as athermocouple, thermistor, or bimetallic thermometer; having aParts ListPart No. Nomenclature Part No. Nomenclature1 upper metal block 12 supporting ring, bottom of inner tube2 lower
22、 metal block 13 control ring3 top cover 14 cover lid, inner tube4 supporting plate, upper metal block 15 elbow5 spacer 16 tube, nylon6 spring, upper metal block 17 main spring7 supporting plate, top of inner tube 18 spacer8 outer tube 19 bearing9 inner tube 20 bimetallic dial thermometer10 disk, dry
23、 ice pushing 21 dial indicator11 clamp, dial gage 22 heat source blockFIG. 1 Schematic Diagram of Frost/Dew-Point ApparatusE546082suitable range graduated in 1C (2F) or smaller units; and anaccuracy of 60.5C (61F) over the full scale. A suggestedcalibration of the bimetallic thermometer is described
24、 inAppendix X1.7. Test Specimen7.1 The specimen to be tested shall be representative of theunits to be evaluated and capable of being positioned horizon-tally.8. Conditioning8.1 Prior to testing, condition the test specimen at a tem-perature of 24 6 3C (75 6 5F) for not less than 24 h.9. Procedure9.
25、1 Preparation of Apparatus:9.1.1 Disassemble the apparatus by taking out the dry icecontainer and retainer 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 is condensed on the
26、 surfaces and walls.9.1.2 Assemble the dry ice container and turn the controlring so that the air gap distance between upper and lower metalblocks is about 13 mm (0.5 in.). Invert the apparatus onto a softcloth.9.1.3 Spray alcohol or acetone (WarningBoth alcoholand acetone are flammable.) on the fin
27、 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. Compress the dry ice with the spring assembly and lockthe cover lid.9.1.4 Return the apparatus to an upright position and secureit onto a horiz
28、ontal surface. Allow sufficient time for thetemperature of the lower metal block to approach that of thedry ice temperature.9.2 Recharging of Apparatus:9.2.1 During the test procedure, replenish the supply of dryice whenever it becomes depleted by turning the apparatusupside down on a soft cloth, op
29、ening the cover lid, taking outthe retainer spring assembly, and repeating steps 9.1.3 and9.1.4.9.3 Determination of Frost State and No-Frost State:9.3.1 Charge the frost/dew point apparatus with dry ice asdescribed in 9.1 or 9.2.9.3.2 Clean both exterior surfaces of the specimen.9.3.3 Place a piece
30、 of silver-colored aluminumized polyes-ter film3(highly reflective mirror surface, not thicker than 0.08mm (0.003 in.) and 25 mm (1 in.) in diameter or 25 by 25 mm(1 by 1 in.) on the measuring surface by wetting both surfacesof the film with acetone or alcohol (WarningSee 9.1.3).Center the specimen
31、on the apparatus. Examine the lower airspace glass surface in the region where frost is to be deposited,to be aware of any dirt or other foreign particles that might bemistaken for frost. Note, however, that a small foreign particleon the lower air space glass surface may be helpful in focusingon th
32、e surface where the frost is to be deposited (see Fig. 2).9.3.4 Slowly reduce the air gap distance between upper andlower metal blocks by turning the control ring while watchingthe temperature of the upper metal block.9.3.5 Bring the temperature of the upper metal block to thetemperature to be check
33、ed for frost and stabilize it by fineadjustment of the control ring. Temperature fluctuation shouldnot exceed 61C (2F).9.3.6 Maintain the stabilized temperature for a duration asfollows:Glass Thickness Designation,mm (in.)Stabilized TemperatureDuration,min2.5 (332)33.0 (185.0 (316)46.0 (14)5NOTE 2Se
34、e Specification C 1036 for glass thickness tolerances.9.3.7 Wipe off the condensation that may have occurred onthe upper exterior surface of glass, or spray the upper surfacewith clear water.9.3.8 Examine the lower air space glass surface in contactwith the measuring surface for frost. Illuminate th
35、is surfacewith a fluorescent desk lamp (two 15-W daylight bulbs), orequivalent for better detection of frost (see Fig. 3).9.3.9 If a clearly visible frost deposit appears on the lowerair space glass surface during or after the temperature stabili-zation period, the frost/dew point of the specimen is
36、 above thisstabilized temperature (frost state) (see Fig. 4 for frost forma-tion). Check for double image of the frost to assure that thefrost lies on the lower air space glass surface (see Fig. 4 B). Ifthe frost deposit is so small and faint that it cannot bedistinguished from dirt or other foreign
37、 particles, lower thetemperature of the measuring surface by 1C (2F) and holdthis value for the duration given in 9.3.6. Reexamine thesuspected particles. If the deposit is frost, its size or populationwill grow or get heavier.FIG. 2 Cross Section of Sealed Insulating Glass Unit for Frost/Dew Point
38、MeasurementE5460839.3.9.1 Frost/dew point determination as described in 9.3.9is difficult to observe on reflective glass. It is acceptable to liftthe specimen off the tester and observe for frost by viewing theunit when held up to light. The observation shall be madewithin5sofremoval from the tester
39、.9.3.10 If frost does not appear after the temperature stabi-lization period, the frost/dew point of the specimen is belowthis stabilized temperature (no-frost state).9.3.11 To check at other temperatures, repeat the test pro-cedure described in 9.3.3-9.3.10 for the temperatures desired.9.4 Determin
40、ation of Approximate Frost/Dew-Point Range:9.4.1 Perform a series of measurements as described in 9.3at successively lower temperatures until frost state is proven.Temperature intervals of 10C (20F) are preferable: forexample, 10C (20F), 20C (0F), 30C (20F), 40C(40F), 50C (60F), and 60C (80F) as des
41、cribed in9.3. Other temperature levels can be checked as desired. Thefrost/dew point will be between the temperature at which frostappeared and the next higher temperature.9.4.2 When the frost/dew-point range can be predicted byexperience (newly fabricated specimen, and so forth), only thetemperatur
42、es bracketing the predicted frost/dew point need bechecked.9.4.3 Estimate the frost/dew point of the specimen withinthe temperature range between frost and no-frost found in 9.4.1by comparing the frost at the lower temperature limit (froststate) with the reference photograph (see Fig. 4) of similart
43、emperature range.9.5 Final Measurement of Frost/Dew Point:9.5.1 Perform a series of no-frost, frost state measurementsdescribed in 9.4 by starting at a few degrees Celsius above theestimated frost/dew point. Lower the temperature by intervalsFIG. 3 Frost/Dew-Point Test Apparatus in UseNOTE 1Number X
44、 means XC below frost/dew point.NOTE 2Size of frost deposit varies with the thickness of glass.FIG. 4 References of Frost Deposit at a Glass Thickness of 5.0 mm (316 in.)E546084of less than 2C (3F) (preferably 1C (2F). If frost appearsat the first starting temperature, reestimate the frost/dew point
45、using Fig. 4 and repeat the test.9.5.2 The frost/dew point is the temperature at which visiblefrost first appears, or between this temperature and the nexthigher temperature that was checked.9.5.3 Record the frost/dew point as the temperature of theupper metal block when the visible frost first appe
46、ars.9.5.4 For repeated measurements of frost/dew point on thesame specimen, allow the frost to evaporate completely, orchoose another spot at least 50 mm (2 in.) away from theprevious measuring spot. Use a counterweight to balance thespecimen. The heat source block (see Fig. 1, Part No. 22) maybe wa
47、rmed and placed in momentary contact with the uppermetal block to raise its temperature before proceeding with arepeated measurement.10. Report10.1 Report the following information:10.1.1 Complete description of the test specimen, includingsize, glass thickness, air space(s) thickness, desiccant typ
48、e andquantity, and sealant type.10.1.2 Specimen conditioning temperature, if other than thatspecified in 8.1.10.1.3 Frost/dew point temperature.11. Precision and Bias11.1 The precision and bias of the test method were deter-mined after assembling various laboratory personnel in onecommon laboratory
49、with their respective test equipment. Alltests were performed on the same set of specially prepared testspecimens.11.2 When the temperature measuring device is calibratedin accordance with 6.1.2 andAppendix X1, the frost/dew pointdifferential measured was within 2C (4F).12. Keywords12.1 building; frost/dew point; insulating glass; sealed in-sulating glass unitsAPPENDIX(Nonmandatory Information)X1. CALIBRATION OF BIMETALLIC THERMOMETERX1.1 Required EquipmentX1.1.1 Secondary Standard Thermometer,
