ASTM E576-88(1999)e1
(Test Method)Standard Test Method for Frost Point of Sealed Insulating Glass Units in the Vertical Position
Standard Test Method for Frost Point of Sealed Insulating Glass Units in the Vertical Position
SCOPE
1.1 This test method describes a field or laboratory procedure for determining the frost point within the air space(s) of sealed insulating glass units, and establishes the criteria for determining whether that point is below or above a given or specified temperature.
1.2 This test method also describes the apparatus to be used for these determinations.
1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Notes 2 and 3.
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Standards Content (Sample)
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Designation: E 576 – 88 (Reapproved 1999)
Standard Test Method for
Frost Point of Sealed Insulating Glass Units in the Vertical
Position
This standard is issued under the fixed designation E576; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript 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.
e NOTE—Keywords were added in October 1999.
1. Scope 3.2 frost state—the case where the frost point of a sealed
insulating glass unit is above the test temperature specified by
1.1 This test method describes a field or laboratory proce-
the purchaser or user.
dure for determining the frost point within the air space(s) of
3.3 no-froststate—thecasewherethefrostpointofasealed
sealed insulating glass units, and establishes the criteria for
insulating glass unit is below the temperature specified by the
determining whether that point is below or above a given or
purchaser or user.
specified temperature.
1.2 This test method also describes the apparatus to be used
4. Summary of Test Method
for these determinations.
4.1 This test method is conducted by the use of a special
1.3 This standard does not purport to address all of the
apparatus, consisting basically of two chilled cylindrical metal
safety concerns, if any, associated with its use. It is the
blocks positioned one over the other and separated by a gap of
responsibility of the user of this standard to establish appro-
controllable distance. The upper block has an exposed flat
priate safety and health practices and determine the applica-
circular surface, 25 mm (1 in.) in diameter, and can be chilled
bility of regulatory limitations prior to use. For specific hazard
to far below the ice point by regulating the air gap distance
statements, see Notes 2 and 3.
between it and the lower metal block which is maintained at
2. Referenced Documents approximately−78°C (−109°F) by dry ice. The test specimen
is placed in contact with this chilled flat circular surface of the
2.1 ASTM Standards:
2 upper block for specified short periods of time, with the metal
C1036 Specification for Flat Glass
surface at successively lower temperatures, to determine at
E77 Test Method for Inspection and Verification of Ther-
3 what temperature frost appears on the corresponding lower air
mometers
space glass surface.
E774 Specification for Sealed Insulating Glass Units
5. Significance and Use
3. Terminology
5.1 This test method is suitable for use under actual or
3.1 frost point—the temperature at which visible frost
simulated in-service conditions; that is, one side of the unit is
begins to deposit on the lower air space glass surface of a
exposed to room temperature, while the other side is exposed
sealed insulating glass unit in contact with the measuring
to natural or simulated weather conditions. Where the glazing
surface of the frost point apparatus.
conditions and the 24-h history are different or changed from
previous conditions, the frost point may not be comparable to
This test method is under the jurisdiction of the ASTM Committee E-6 on
a previous measurement.
Performance of Buildings and is the direct responsibility of Subcommittee E06.22
5.2 This test method is applicable for the uncoated or
on Durability Performance of Building Constructions.
unfilmed clear (transparent) glass pane of sealed insulating
CurrenteditionapprovedMarch25,1988.PublishedSeptember1988.Originally
published as E576–76. Last previous edition E576–79.
glassunits.Ifthisapparatusisusedwithcoatedorfilmedglass
Annual Book of ASTM Standards, Vol 15.02.
pane, the coating or film on the surface of glass pane may be
Annual Book of ASTM Standards, Vol 14.03.
4 damaged.
Annual Book of ASTM Standards, Vol 04.11.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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E 576 – 88 (1999)
Parts List
Part No. Nomenclature Part No. Nomenclature
1 front metal block 12 supporting ring, bottom of
inner tube
2 rear metal block 13 control ring
3 top cover 14 cover lid, inner tube
4 supporting plate, front metal 15 elbow
block
5 spacer 16 tube, nylon
6 spring front metal block 17 main spring
7 supporting plate, top of 18 spacer
inner tube
8 outer tube 19 bearing
9 inner tube 20 bimetallic dial thermometer
10 disk, dry ice pushing 21 dial indicator
11 clamp, dial gage 22 heat source block
FIG. 1 Schematic Diagram of Frost Point Apparatus
5.3 This test method may require minor modifications to The two metal blocks are separated by a small air gap, the
keep the measuring surface of the frost point apparatus in distance of which can be regulated by the control ring. The
contact with the glass if the insulating glass unit is not in the exposedflatcircularsurfaceoftheupperblockis25mm(1in.)
true vertical position.
in diameter, has a ground or lapped finish, and when placed in
contact with the glass test specimen, forms the frost point
6. Apparatus
measuringsurface.Thelowerblockischilledbyadryicepack
6.1 Test Apparatus (see Fig. 1), consisting of upper and
kept in contact with it by the retainer spring assembly,
lowercylindricalmetalblocks,withathermocouple,bimetallic
maintaining it at a temperature near to that of sublimating dry
thermometer, or other suitable temperature sensors being
ice (−78°C (−109°F)). Because the solid metal blocks are
inserted in the upper block; a control ring; and an insulated
highlyconductive,thetemperatureofeachisvirtuallyuniform.
containment cylinder fitted with a retainer spring assembly.
Useofthecontrolringadjuststheairgapdistancebetweenthe
two blocks to give the desired thermal resistance across the air
5 gap. The circular measuring surface of the upper block is thus
Available from Dennis Industries, 20032 Waynegarden Court, Germantown,
MD 20874. readily adjusted to the desired temperature while in contact
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E 576 – 88 (1999)
with the test specimen. The circular measuring surface diam- 6.3 Glass Thickness Gage (see Fig. 3).
eter specified is suitable for frost point measurement of glass
7. Test Unit
up to 6.0 mm ( ⁄4 in.) thick.
7.1 The sealed insulating glass unit to be tested should have
6.1.1 UpperandLowerBlocks,aluminumalloythatmaybe
anodized,conformingtothedimensionsshowninFig.1.Other a clear glass pane (see 5.2) in contact with the measuring side
of the test apparatus and shall be positioned vertically.
parts of the apparatus may be fabricated from any appropriate
materials.
8. Conditioning
6.1.2 Calibrated Temperature-Measuring Device, such as a
8.1 Condition the unit to be tested at room temperature on
thermocouple, thermistor, or bimetallic thermometer, having a
bothunitsidesbyexposingtoatemperatureof24 63°C(756
suitable range graduated in 1°C (2°F) or smaller units, and an
5°F) for not less than 24 h prior to the testing.
accuracy of 60.5°C (61°F) over the full scale. A suggested
8.2 Condition the unit to be tested under simulated in-
calibration of the bimetallic thermometer is described in
service conditions by exposing to temperatures within 63°C
Appendix X1.
(65°F)ofthedesiredsimulatedconditionsfornotlessthan24
6.2 VerticalAttachmentFixture (seeFig.2),consistingofa
Parts List
Part No. Nomenclature
1 rubber vacuum cup
2 guide rod
3 clamping spring
4 vacuum hand lever
5 hand grip
6 spring post
FIG. 2 Vertical Attachment
twin-grip vacuum cup holder, two parallel guide rods, two h prior to testing.
spring posts, and two clamping springs. The vacuum cup is 8.3 For the unit to be tested under actual in-service condi-
made of rubber. When the vertical attachment fixture is placed tions, record or obtain the ambient temperatures of both sides
on the surface of clean glass and the vacuum hand lever is oftheunitatthestartandendofaparticularmeasuringperiod,
pushed down, the vertical attachment fixture becomes firmly and the 24-h temperature history prior to testing.
attached to the glass surface. Other equivalent attachment
NOTE 1—At the present time, there is insufficient information to
fixtures may be used.
comparethemeasuredfrostpointoftheunitfromthereportedtemperature
Adevice found suitable for this purpose, U.S. Patent No. 3320849, is available
from J. R. Cumberland, Precision Optics, 4505 Beech Rd.,Washington, DC 20031.
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E 576 – 88 (1999)
(a) Gage (b) Gage in Use
FIG. 3 Glass Thickness Gage
history to that implied in-service level of the unit. However, the tempera-
9.3.2.4 Read the minimum thickness of the glass above.
turehistorywillprovideavaluablebasisforevaluatingthein-servicelevel
9.3.3 Placethefrost-pointapparatusontopoftheguiderods
and life of the unit in the future.
of the vertical attachment fixture, facing the measuring surface
ofthefrost-pointapparatustowardtherubbervacuumcup,and
9. Procedure
slidebothguidefinsofthefrost-pointapparatusinbetweenthe
9.1 Preparation of Frost-Point Apparatus:
guide rods from the rear end.
9.1.1 Disassemble the apparatus by removing the dry ice
9.3.4 Hook each clamping spring to the hooks of the
container and retainer spring assembly. Carefully clean the
frost-point apparatus.
measuringsurfacewithasoftclothorpaper.Donotscratchthe
9.3.5 Clean the exterior glass surface where the frost-point
measuring surface.Wipe and clean the apparatus thoroughly if
apparatus and the vertical attachment fixtures are to be placed.
any moisture has condensed on the surfaces and walls.
Measure the frost point within an area at least 250 mm (10 in.)
9.1.2 Assemble the dry ice container and turn the control
away from the spacer or at the center of the unit. Examine the
ring so that the air gap distance between front and rear metal
interiorairspaceglasssurfaceintheregionwheredeworfrost
blocksisabout13mm(0.5in.).Inverttheapparatusontoasoft
is to be deposited, to be aware of any dirt or other foreign
cloth, or a suitable mounting bracket.
particles that might be mistaken for frost. However, a small
9.1.3 Spray alcohol or acetone (Warning—See Note 2)on
foreign particle on the interior air space glass surface may be
the fin of the dry ice container to ensure good contact with the
helpful in focusing on the surface where the frost is to be
dry ice. Compactly charge the container with the crushed or
deposited.Avoidtheareawheresunlightstrikesdirectlyonthe
pulverized dry ice up to the “full” mark. Compress the dry ice
unit or shade it from direct sunlight.
with the spring assembly and lock the cover lid.
9.3.6 Release both vacuum hand levers of the vertical
NOTE 2—Warning:Both alcohol and acetone are flammable.
attachment fixture.
9.1.4 Turn the apparatus to an upright position. Allow 9.3.7 Clean the surfaces of the rubber vacuum cups, and the
sufficient time for the temperature of the rear metal block to
measuring surface and front surface of the frost-point appara-
approach near that of the dry ice temperature. tus. If there are any water vapor or frost deposits on the
9.2 Recharging of Frost Point Apparatus—During the test
measuring surface of the frost-point apparatus, clean the
procedure,replenishthesupplyofdryicewheneveritbecomes measuring surface by wetting with alcohol (Warning—See
depleted by inverting the apparatus onto a soft cloth, opening
Note3).Ifthemeasuringsurfaceisheavilyscratched,thefront
the cover lid, taking out the retainer spring assembly, and metal block should be replaced or repaired. If the dew or frost
repeating steps 9.1.3 and 9.1.4. deposit can be checked from the other side of the unit as
9.3 Determination of Frost State or No-Frost State: described in 9.3.15, a piece of silver-colored aluminized
9.3.1 Charge the frost-point apparatus with dry ice as polyester film (with a highly reflective surface, not thicker
described in 9.1 or 9.2. than 0.08 mm (0.003 in.), and 25 mm (1 in.) in diameter, or 25
9.3.2 Measure the thickness of glass in the measuring side by 25 mm (1 by 1 in.) can be placed on the measuring surface
as follows: by wetting both surfaces with alcohol.
9.3.2.1 Place the long side of the glass thickness gage (see
NOTE 3—Warning:Alcohol is flammable.
Fig. 3) against the glass pane at a 45° angle.
9.3.2.2 Observe the reflection in the glass. 9.3.8 To provide better thermal contact, wet the measuring
9.3.2.3 Note where the long line superimposes the short surface of the frost point apparatus and exterior glass surface
line. where it is to be contacted with alcohol (see Note 3).
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E 576 – 88 (1999)
9.3.9 Hold the hand grip of the vertical attachment fixture adjustment of the control ring. Temperature fluctuation should
with one hand in a level position. Contact the measuring not exceed 61°C (62°F).
surface against the wetted glass surface and push the vertical
9.3.14 Maintain the stabilized temperature for a minimum
attachment so that both rubber vacuum cups touch flatly time duration as follows:
against the glass surface (see Fig. 4).
Glass Thickness Designation, Stabilized Temperature—Duration,
mm (in.) minimum, min
9.3.10 Slowly flip the vacuum hand levers to a locking
2.5 ( ⁄32)3
position so that the vertical attachment fixture is held firmly
3.0 ( ⁄8)3
against the glass surface of the unit. If a vacuum cup does not
5.0 ( ⁄16)4
6.0 ( ⁄4)5
hold the vacuum properly, release the vacuum hand lever and
flip it again while applying a little more force. Make sure that
NOTE 5—See Specification C1036.
the measuring surface and front surface of the frost-point
9.3.15 If the other side of the unit is accessible, clean the
apparatus are flush with the glass surface. If it is not flush with
exterior glass surface and examine the interior air space glass
the glass surface, adjust it by either increasing the tension of
surface in contact with the measuring surface. Illuminate the
the clamping springs or adjusting the guide rod. If needed,
interior air space glass surface with a flashlight for better
shim the guide rod.
detectionoffrostdeposit,ifneeded.Iftheothersideoftheunit
NOTE 4—Warning:Take care that the vertical attachment fixture does
is not accessible, unhook the clamping spring and slide out the
not fall off during the measurement.
frost point apparatus far enough to examine the interior air
9.3.11 Wipe off the excessive alcohol running down the
space glass surface. Then, quickly examine the interior air
glass surface from the measuring surface before it reaches the space glass surface for frost deposit. If the frost forms or water
glazing materials. vapor condenses on the exterior glass surface where the
9.3.12 Slowlyreducetheairgapd
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