GE Structured Products LEXAN Thermoclear Multi-wall Polycarbonate

Technical Manual

LEXAN®Thermoclear ® Multi-wallPolycarbonate Sheet

LEX

AN

gGE Structured Products

®

Product availability*

P ro d u c t Av a i l a b i l i t yLEXAN polycarbonate is a unique engineering thermoplastic whichcombines a high level of mechanical,

optical, thermal and electrical properties. The versatility of thismaterial makes it suitable for many engineering applications.When extruded in sheet form, its optical and impact propertiesin particular render this material a strong candidate for a widerange of glazing applications. The GE Structured Productsgroup has developed a whole range of products to suit themost demanding of these application needs.

LEXAN® Multiwall Sheet

LEXAN Thermoclear sheet is animpact resistant, energy-saving, multiwall polycarbonate glazingsheet. It features a proprietary surface

treatment which provides resistance against degradationcaused by UV radiation in sunlight. The entire LEXANThermoclear sheet range of products carries a Ten YearLimited Warranty* against discoloration, loss of light transmission and/or loss of strength due to weathering.Typical applications include:• Skylights/Overhead Glazing• Atriums, Canopies and Walkways• Industrial Roofs and Sidewalls• Sunroom, Swimming Pool

and Conservatory Roofing• Shopping Center Roofing• Railway/Metro Station• Football Stadium Roofing

LEXAN Thermoclear Dripgard sheet,in addition to the properties of standard LEXAN Thermoclear sheet,

also features a specially developed coating on the inner sur-face which reduces the formation of condensation droplets.This property is particularly important in helping to preventcrop spoilage in commercial greenhouses, by falling conden-sation droplets. There is no reduction in light transmissiondue to condensation water droplets. It is an excellent roofglazing material in any application where water drops areunacceptable. For instance: greenhouses verandas/sunrooms/swimming pool enclosures/industrial roof glazing.

LEXAN Profiled Sheet has the sameconstruction, physical, mechanical

and thermal properties as LEXAN Thermoclear sheet, but it doesnot feature the latter’s proprietary surface protection against UVradiation. It is specifically recommended for internal secondaryglazing and other indoor uses such as partitioning, shower stallsand false ceilings.

LEXAN®

Polycarbonate Resin

LEXAN®

Thermoclear® Sheet

LEXAN®

Thermoclear®

Dripgard Sheet

LEXAN®

Profiled Sheet

LEXAN Multiwall Sheet Structures:

2 R - Twin Wall Rectangular Structure

3 T - Triple Wall Structure

4 RS - Four Wall Rectangular Structure

5 RS - Five Wall Rectangular Structure

6 RS - Six Wall Rectangular Structure

LEXAN Thermoclear Dripgard Sheet:Standard SpecificationProduct Code

LTD2R6LTD2R8

Product Code Gauge in Inches Width in Inches

Core Products

LTC 2R6 0.236 48, 72

LTC 2R8 0.312 48, 72, 83

LTC 2R10 0.395 48, 72, 83

LTC 3T16 0.624 48, 72, 83

Value Added Product

LTC 16/4RS 3000 0.624 38.58, 49.21, 82.68

LTC 20/5RS 3300 0.787 38.58, 47.24, 82.68

LTC 25/6RS 3500 0.984 38.5, 47, 49

LTC Venetian Ask for availability

1* See limited warranty for details

P ro p e r t y P ro f i l eTypical property values for LEXAN Thermoclear Sheet (LTC), LEXAN Thermoclear Dripgard Sheet (LTD) and LEXAN Profiled Sheet (LPS) are indicated in the following table:

Sheet thickness mm 6 8 10 16 16 20 25

Structures 2R6 2R8 2R10 3T16 4RS 5RS 6RS

Approx. weight g/m2 1300 1700 2000 2800 3000 3300 3500

Approx. weight lbs/ft2 .27 .35 .41 .57 .61 .68 .72

Clear code 112

Light transmission % 82 82 80 76 75 64 44

Solar transmission % 86 86 85 82 80 75 58

Bronze

Standard 5109 Light transmission % 50 50 50 50 23

Europe 515055Light transmission % 35 35

White

Opal 875074Light transmission % 40 40 40 40

Standard 825075Light transmission % 20 20 20 20

Europe 82995Light transmission % 48 38 24

U.Value Btu/Hr x Ft2 x ˚F 0.61 0.58 0.52 0.42 0.37 0.31 0.27

LEXAN®

Multiwall Sheet

ASTM UNITS

VICAT VST/B/120 °F 293

HDT@264 PSI D648 °F 275

Thermal conductivity C177 BTU/HR x Ft2 x ˚F 1.35

Coefficient of linear thermal expansion D696 In/In °F 3.75 x 10-5

Refractive index D542 - 1.586

Fig. 1

Typical properties

2

M e c h a n i c a l P ro p e r t i e sLEXAN Thermoclear sheet has out-standing impact performance over awide temperature range, -40°F to

+248°F, and also after prolonged outdoor exposure.

The principle of the GE Plastics modified Gardner falling dart impacttest is as follows: The specimen is

placed over a hole of 1 inch diameter in a die mounted on theanvil. The round nosed dart, .5 inch diameter, is placed uponthe specimen. The dart with a mass of 8.8 pounds is raised tothe desired height in a 3.3 foot calibrated tube, and dropped.The maximum applied impact energy is given as:

M x h = 8.8 x 3.3 = 29 foot-pounds

The test specimen is considered to have passed the test if thesample shows no visible signs of surface cracks around theimpact area.

As a roofglazing material, LEXANThermoclear sheet is subjected to the extremes of weather; storms,

hailstones, wind, snowfalls and ice formation. Under these conditions, the product is exceptionally tough and is able to accommodate the subsequent temperature change to sunnyconditions without breaking or buckling.

Gardner Impact

60

7.4

14.7

22

29.5

8 10 16 Acrylic Glass

Lexan Thermoclear Sheet Gardner Falling Dart Impact

impact energy = ft-lbs. force

73.4Fgauge in mm -20-4F

In a test developed by the Dutch Testing Institute TNO, samples of LEXAN Thermoclear sheet have been subjected tosimulated hail stones of varying diameters of up to 1.2 incheswithout significant damage. A test sample is clamped into ametal frame 10 ft x 13 ft and polyamide balls of varying diameters are fired at the surface of the sample using a pressurized air gun. The ball diameter and velocity are variedduring the test.

In practice, hailstones with diameter of 3/4 inch can reach a terminal velocity of some 47 mph. Under these conditions materials such as glass and acrylic typically fail.

Table 4 lists the results of a series of tests on three materials.The values indicated relate to the failure velocities versus balldiameter for the different materials tested.

It should be noted that when the glass and the acrylic are tested their failure characteristics are typically brittle, while the LEXAN Thermoclear sheet shows a ductile deformationzone, i.e. small indentations. GE Plastics offers a Ten YearLimited Warranty on LEXAN Thermoclear sheet covering lossof strength or impact due to weathering.

Glazing materials in sports halls areoften subjected to impacts causedby a variety of balls used in manydifferent games. A sample of LEXAN

Thermoclear sheet, 78 x 78 inches and thickness 16 mm,tested according to German DIN Standard 18032, has beenclamped on all four sides and exposed to severe impactsfrom numerous hand and hockey balls. The balls were firedat the test sample at different angles and velocities.

The LEXAN Thermoclear sheet sample showed no visibledamage and easily passed the test.

Impact Strength

Hail Simulation

Sports Ball Impact –DIN 18032 (part 3)

Hail Simulation Test Results

Ball diameter

Material .39 in. .78 in. 1.18 in.

Acrylic multiwall sheet 16 mm 36-45 mph 16-31 mph 9-22 mph

Float glass 4 mm 67 mph 22 mph 18 mph

LEXAN Thermoclear sheet 10 mm >111 mph 98 mph 63 mph

LEXAN Thermoclear sheet 16 mm >111 mph 98 mph 63 mph

Equilibrium velocity hail 31 mph 47 mph 56 mph

max

imum

dro

p he

ight

: 39"

max

imum

impa

ct e

nerg

y:29

ft-p

ds.

falling dart weight: 8.8 pounds

calibratedguide tube

metal round nosed punch .5 inch diameter

Lexan Thermoclear sheet specimen

1 inch

Fig. 4

Fig. 3

Fig. 2 Gardner impact tester

*See limited warranty for details 3

P h y s i c a l P ro p e r t i e sThe sunlight which reaches the sur-face of the earth has a wavelengththat ranges between 295 - 2140

nanometers (10-9 meters). This optical window is divided intothe following sections:

UV-B Middle ultra-violet region 280 - 315 nmUV-A Near ultra-violet region 315 - 380 nmVisible light region 380 - 780 nmNear infra-red region 780 - 1400 nmMiddle infra-red region 1400 - 3000 nm

As shown in Figure below LEXAN Thermoclear sheet has the maximum transmission in the visible light region.

Despite transmitting visible light very well, LEXANThermoclear sheet is almost opaque to radiation in the UVand far infra-red region. This useful shielding property canprevent discoloration of sensitive materials such as fabrics or other organic materials placed under or behind LEXANThermoclear sheet glazing in, for example, a factory warehouse, museum or shopping center.

The same properties, in combinationwith the insulating multiwall struc-ture, contribute to a temperatureincrease inside the building.

Sunlight entering the building heats the air both directly and through absorption by framework, furniture etc., and isreleased as infra-red energy. The insulating properties ofLEXAN Thermoclear sheet prevent this heat escaping fasterthan it is created, causing a temperature increase—the so-called ‘greenhouse effect’. The temperature can be controlledby venting often in combination with specially tinted LEXANThermoclear sheet.

Transparent grades of LEXANThermoclear sheet have excellentlight transmission, between 64 and

82% depending upon thickness. However, for buildings in hotclimates or with south facing aspects. LEXAN Thermoclearsheet is available in translucent grades of bronze, grey, blue,green and opal white. These grades significantly reduce solarheat build up, helping to maintain comfortable interior temperatures.

The specially tinted sheet cuts down the brightness of sun-light to a pleasing level and reduces air conditioning costs in the summer.

The solar radiation reaching thesheet is reflected, absorbed andtransmitted as shown in Figure 6.

The greatest proportion is transmitted and the total solartransmission (ST) is the sum of the direct transmission (DT)and the inwardly released part of the absorbed energy (A).Table 7 outlines the overall solar control properties ofLEXAN Thermoclear sheet.

Light transmission

TemperatureIncrease Insidethe Building

Solar Control

Solar Heat Gain

Total Solar Transmission (ST) in %

LTC LTC LTC LTC LTC16 LTC20 LTC25Material 2R6 2R8 2R10 3T16 4RS 5RS 6RS

Clear 112 86 86 85 82 80 75 58

Bronze 5109 60 60 60 33515055 55 55

White825074 50 50825075 30 30 3082995 71 65 34

Fig. 5

Fig. 6

Fig. 7

4

O u t d o o r We a t h e r i n g P e r f o r m a n c eSolar radiation has a particularlyharmful effect upon polymeric materials initiating degradation by

causing superficial surface crazing. These crazes become sitesfor further erosion from water, dust, chemicals etc. The degreeto which these conditions affect the polymer depend largelyupon environmental parameters such as geographical location, altitude, seasonal variations, etc.

LEXAN Thermoclear sheet has a UV-protected surface, giving durability to outdoor weathering. The unique technolo-gy applied to LEXAN Thermoclear sheet helps to ensure longterm optical quality under intensive UV exposure, and main-tain the superior toughness of the polycarbonate material incomparison to other thermoplastic glazing.

Research into the long term effects ofweathering on glazing materials isbasically focused upon measuringproduct performance through material

property changes, typically mechanical strength, impact resistance, color retention, transparency, etc.

A test was developed using high intensity xenon lamps tosimulate natural sunlight. Together with other suitable UV filters and programmable rain cycles the test is able to simulate natural conditions.

Accelerated weathering tests were carried out in the Xenon1200 apparatus to ISO 4892, however with a higher UV part inthe xenon light during 1/6 of the carousel cycle. Placed withinthis environment, LEXAN Thermoclear sheet was exposed to5000 hours. Experience with the Xenon test equipment indi-cates this relates to approximately 15 years natural exposurein a moderate European climate. Following the test the opticalproperties of light transmission and yellowness index weremeasured and compared with an un-aged sample. Figures 8and 9 indicate the changes in the values over the simulated 15year period of LEXAN Thermoclear sheet (standard Cleargrade).

The heat build-up of glazing materialscan be seen as a function of theabsorption of the glazing material and the solar intensity.

In countries with intense sun radiation, and when high energy absorbing tinted glazing is installed, heat build-up ofthe glazing can be considerable. Calculations and actual measurements on installed LEXAN Thermoclear sheet in several projects throughout Europe have shown that sheetsurface temperatures of 212°F can exist.

LEXAN Thermoclear sheet is characterized by its retention ofimpact strength and stiffness at elevated temperatures, evenover an extended period.

LEXAN Thermoclear sheet retains 85% of its room temperature flexural modulus at 176°F. The Vicat softeningtemperature and the Deflection Temperature Under Load ofLEXAN polycarbonate are both around 284°F.

LEXAN Thermoclear sheet has a continuous-use temperatureof 212°F*. At the other end of the scale the minimum continu-ous-use temperature has been set at -40°F. Using LEXANThermoclear sheet at lower temperatures is possible since theembrittlement temperature can be as low as -80°F.

UV Protection

TemperatureResistance

Typical Values ofThermoclear Sheet

WARRANTYGE Plastics offers a Ten Year Limited Warranty on LEXANThermoclear sheet covering discoloration, loss of light transmission and loss of strength due to weathering. Please consult your local distributor or GE StructuredProducts Sales Office for specific details.

Fig. 8

Fig. 9

*As rated by UL.

*Test performed on 20mm Thermoclear®

5

Va r i o u s P ro p e r t i e s

U.L. Temperature Ratings UL746B

Underwriters LaboratoriesContinuous-use Temperature Rating

LEXAN Polycarbonate 212°FAcrylic 122°FP.V.C. 122°F

The U.S.A. Underwriters Laboratoriescontinuous-use temperature rating

can be considered as a reliable indicator of a thermoplastic’slong-term high temperature performance. Important proper-ties of the thermoplastic are tested at various temperatures.Test results are extrapolated over a period of 10 years and noproperty may lose more than 50% of its original value. Figure10 outlines the UL-continuous-use temperatures of typical thermoplastic glazing materials.

UL Ratings

LEXAN Thermoclear Fire Classification*

Country Norm Classification

USA Model Bldg. Codes Approved LightTransmittingPlastics

Germany DIN 4102 B1 (to 10 mm)part 1 B2 (16 mm)

United-Kingdom BS 476 part 7 Class 1Building Class 0Regulations Tp (a)(1991)

France NF-P-92-507 M1-M2

Netherlands NEN 6065 Class 1-2

*dependent on thickness and color

LEXAN® Thermoclear® sheet hasgood fire behavior characteristics,and receives high ratings in several

major European fire performance tests. As a thermoplastic,LEXAN Thermoclear sheet will typically melt under the intense heat of a fire.

Fire Performance

Weight

Material Thickness Weightmm lbs/ft2

LEXAN Thermoclear Sheet 6 .27LEXAN Thermoclear Sheet 8 .35LEXAN Thermoclear Sheet 10 .41LEXAN Thermoclear Sheet 16 .57LEXAN Thermoclear Sheet 20 .68LEXAN Thermoclear Sheet 25 .72

LEXAN Thermoclear sheet can be an ideal replacement for the more traditional glazing materials. It is safe

and easy to handle, cut and install and is extremely tough. Itslight weight offers significant savings in terms of transportation,handling and installation. When compared with 6 mm wiredglass, 10 mm LEXAN Thermoclear sheet offers weight savingsof more than 85%.

LEXAN Thermoclear sheet has shown in many applicationsthat its lightness and ease of handling have contributed to significant savings in overall installation cost.

Weight Factors

N.B. More detailed information is available fromyour local GE Structured Products Service Center orauthorized dealer. These tests are not intended toreflect the performance of this or any other materialunder actual fire conditions.

Sound Reduction Values

Material Thickness STCmm Rating

LEXAN Thermoclear Sheet 6 17LEXAN Thermoclear Sheet 8 19LEXAN Thermoclear Sheet 10 21LEXAN Thermoclear Sheet 16 22

The sound insulation characteristics ofa material are largely predetermined

by its stiffness, mass and physical construction. The maximumobtainable sound transmission class for LEXAN Thermoclearsheet is:

Sound Insulation

Fig. 10

Fig. 11

Fig. 12

Fig. 13

6

T h e r m a l p ro p e r t i e s

Expected calculation exampleAnnual fuel saving when glass is replaced by LEXANThermoclear sheet.

Data:

4 mm Glass, U-value - 1.02 Btu/Hr x ft2 x °F10 mm LEXAN Thermoclear sheet, U-value - 0.52 Btu/Hr x ft2 x °F

6.7 – Gallon of oil of annual savings989 – Cubic ft of gas of annual savings

Overglazing

Glass Air space Thermoclear U-valueThickness inches Thickness Btu/Hr x ft2 x °F.

4 1-2 6(2R6) 0.384 1-2 8(2T8) 0.374 1-2 10(2R10) 0.354 1-2 16(3T16) 0.30

Installing LEXAN Thermoclear sheetin front or LEXAN profiled sheet

behind the existing glazed window provide additional energysavings. For effective insulation, the best results are typicallyobtained leaving a .75 - 2 inch air gap between the existingglazing and the LEXAN multiwall sheet.

Overglazing

Double LEXAN Multiwall Sheet Units

Thermoclear Air gap Profiled sheet u-valuesheet Outside inches Inside Btu/Hr x ft2 x °F

6(2RS) .75 - 2 4.5(2R) 0.328(2TS) .75 - 2 4.5(2R) 0.31

10(2RS) .75 - 2 6(2R) 0.2816(3TS) .75 - 2 6(2R) 0.2516(3TS) .75 - 2 10(2R) 0.22

Extremely low U-values can beobtained by double-glazed multiwallLEXAN sheet units. A combination ofLEXAN Thermoclear sheet outside and

LEXAN profiled sheet inside, with an air gap of .75 - 2 inchescan dramatically reduce the heat loss factor in applications suchas curved and pitched roof lights.

Double LEXANMultiwall SheetUnits

The need to reduce energy consump-tion, and therefore energy costs, isone of the highest priorities in any

business today. Substantial savings in the order of more than50% are possible when installing LEXAN Thermoclear sheetinstead of mono-layer glass. When calculating according tothe guidelines outlined in the DIN standard 4701, an averageannual saving between .2 - .3 gal. of oil or 35.3 - 53 ft3 of gasper 10 ft2 of glazing area is obtained by decreasing the U-valueby 0.018 Btu/Hr x ft2 x °F.

Table 17 shows the minimum and maximum expected amountof savings of fuel consumption per 10 ft2 glazing area at various U-value differences.

Energy LossCalculations

U-value difference: 1.02 – 0.52 = 0.50 Btu/Hr x ft2 x °F,acc. table 17 minimum and maximum expectedamount of annual fuel saving per 10. ft2 glazing area.

Material u-values (Btu/Hr x ft2 x °F)

Materials Thickness mm U-value

LEXAN Thermoclear 6 (2R6) 0.61LEXAN Thermoclear 8 (2T8) 0.58LEXAN Thermoclear 10 (2R10) 0.52LEXAN Thermoclear 16 (3T16) 0.42LEXAN Thermoclear 16 (4RS) 0.37LEXAN Thermoclear 20 (5RS) 0.32LEXAN Thermoclear 25 (6RS) 0.27

The multiwall structure of LEXAN®

Thermoclear® sheet offers significantadvantages where thermal insulation

is a major consideration. The hollow form provides insulationcharacteristics with heat losses significantly lower than mono-wall glazing materials. Heat loss is normally referred to as the U-value, which is the amount of energy transmittedthrough a material per square foot of glazing area and perdegree temperature difference. It is expressed in terms ofBtu/Hr x ft2 x °F.

Thermal Insulation

Fig. 14

Fig. 15

Fig. 16

7

T h e r m a l p ro p e r t i e s

U-valuedifference Expected annual saving per 10.0 ft2 glazing areaBtu/Hr x ft2 x OF

Oil - gallon Gas - ft3

0.02 .02 - .3 35 - 53

0.04 .48 - .67 71 - 106

0.05 .71 - 1.0 106 - 159

0.07 .95 - 1.4 141 - 212

0.09 1.2 - 1.7 176.5 - 265

0.11 1.4 - 2.1 212 - 318

0.12 1.7 - 2.4 247 - 371

0.14 1.9 - 2.7 282.5 - 424

0.16 2.1 - 3.1 318 - 477

0.18 2.4 - 3.4 353 - 530

0.21 2.9 - 4.1 424 - 635.5

0.25 3.3 - 4.8 494 - 741.5

0.28 3.8 - 5.5 565 - 847.5

0.32 4.3 - 6.2 635.5 - 953.5

0.35 4.8 - 6.9 706 - 1059.5

0.39 5.2 - 7.6 777 - 1165

0.42 5.7 - 8.2 847.5 - 1271

0.46 6.2 - 8.9 918 - 1377

0.49 6.7 - 9.6 989 - 1483

0.53 7.1 - 10.3 1059.5 - 1589

0.56 7.6 - 11 1130 - 1695

0.60 8.1 - 11.7 1200.5 - 1801

0.63 8.6 - 12.4 1271 - 1907

0.67 9 - 13.1 1342 - 2013

0.70 9.5 - 13.7 1412.5 - 2119

Note:The exact amount of annual fuel savings are strongly dependent upon building type, location and regional environment conditions. Local authority engineering departments usually have official data relating to average temperature differences during the heating time necessary.

The insulation properties of LEXAN®

Thermoclear® sheet will also contribute to lesser cold emission

towards the building. The lower the U-value the higher theinner sheet surface will be maintained during the winter season.

Here is an example of the temperature profile through LEXANThermoclear 6 mm sheet when the outside temperature is14°F and the inside building temperature is 68°F.

The multiwall construction creates an airspace which results ina moderate sheet surface temperature difference.

During the conditions indicated the inner sheet surfaceremains far above freezing temperature so that there is nocold radiation to the inside of the building.

Temperature process through Thermoclear sheet at low outside temperature.

Cold Emission

Compared to single glazed glass, in the same conditions, theinside glass surface will be far below freezing temperature.Cold radiation will negatively influence the overall buildingtemperature and will affect the comfort level near the windows.

Fig. 17

Fig. 18

Fig. 19

8

Periodic cleaning using correct procedures with compatible household cleaners is recommended

to prolong service life.

For general cleaning, it is recommended that the followinginstructions be adhered to.

C o n d e n s a t i o n / C l e a n i n gCleaning

Cleaning Agents Which Have Been Found to be Compatible with LEXANThermoclear Sheet Under Laboratory Conditions

Joy1 various

Palmolive Liquid2 various

Top Job1 various

VM&P grade Naptha various

Condensation is formed when moisture in the atmosphere changesback to water as it comes into contact

with a surface at a temperature below the `dewpoint’ of thesurrounding air.

Water droplets on the surface of the glazing reduce light transmission, and, if they fall, can spoil plants or damage sen-sitive goods and equipment beneath. LEXAN® Thermoclear®

Dripgard sheet has a special one-side coating that inhibits theformation of condensation droplets. The coating lowers thesurface tension and the drops form a thin layer of water overthe whole surface of the sheet.

When the sheet is correctly installed, this thin, transparentwater film runs off the sheet surface into the profile drainagesystem without falling to the ground and without significantlyaffecting the light transmission values of the glazing.

Figure 20 shows a typical condensation prediction chart showing the relationships between internal and external temperature, relative humidity and the U-value. The dottedlines on the chart illustrate clearly how glass with a high U-value is more prone to condensation than the LEXANThermoclear sheet.

Condensation

1. LTC 20 mm at a humidity content of: 68%2. LTC 6 mm at a humidity content of: 50%3. Glass at a humidity content of: 32%

Procedure 1 - Small Areas

1. Rinse sheet with lukewarm water.2. Wash sheet with a solution of mild soap or

household detergent and lukewarm water, usinga soft cloth or sponge to loosen any dirt andgrime.

3. Rinse with cold water and dry with a soft cloth toprevent water spotting.

Procedure 2 - Large Areas

1. Clean surface with a high pressure water and/orsteam cleaner.

2. Use of additives to the water should be restrictedto those compatible with LEXAN Thermoclear sheet.

Never use an abrasive or highly alkaline cleaner on LEXANThermoclear sheet.

• Cleaners and solvents generally recommended for useon polycarbonate are not necessarily compatible with the UV-protected surface of LEXAN Thermoclear sheet.

• DO NOT USE either BUTYL CELLOSOLVE or ISOPROPANOL on the UV-protected surface of LEXAN Thermoclear sheet.

• Never scrub with brushes, steel wool or other abrasive materials.

IMPORTANT

Fig. 20

Fig. 21

Example:Inside temperature: 68°FOutside temperature: 14°FCondensation will occur on:

9

Thermoclear sheet has been success-fully used in combination with manybuilding materials and glazing

compounds. Taking into account the complexity of chemicalcompatibility, all chemicals which come into contact with thepolycarbonate should always be tested. For sheet products the most common materials are sealants, gaskets and the various cleaning media. Chemical compatibility testing is an ongoing process at GE Structured Products and many standard products have already been tested. A complete list of recommended cleaners, gaskets and sealants is available;however, a shortened list of some of the more common compounds is outlined in these sections.

C h e m i c a l R e s i s t a n c eChemical Resistance

Recommended Sealants, Gaskets and Tapes

Type Manufacturer Product Name

Silicone General Electric Company Ultrapruf SealantWaterford, NY(800) 255-8886

Silicone General Electric Company Silipruf® SealantWaterford, NY(800) 255-8886

Silicone General Electric Company CONSTRUCTIONWaterford, NY 1200® Sealant(800) 255-8886

Silicone General Electric Company CONSTRUCTIONWaterford, NY 1000® Sealant(800) 255-8886

Gasket/Tape Norton Company • NORRENE* FoamGranville, NY • V-2100 Urethane(800) 724-0883 Series

Gasket Tremco • Silicone (70Columbus, OH Durometer)(800) 321-6357 • EPDM (60, 70

Durometer)Tape Tremco 440 Tape

Cleveland, OH(800) 321-6357

Butyl Tape PTI 303, 606Dayton, OH(800) 543-7570

Butyl Tape Schnee-Morehead Isocryl 5600Irving, TX Series(214) 438-9111

Aluminum/ DRG Sellotape Sellotape BVMesh Tape Utrecht, Holland Vent Tape

030-44 33 44Vent Tape 3M Tape 394, 3294

Minneapolis, MN(612) 733-1110

Vent Tape ITP MuerifireAnnapolis, MD AD 3429(410) 757-5040

When using glazing compounds it is essential that the sealantsystem accepts a certain amount of movement, to allow forthermal expansion, without loss of adhesion to the frame orsheet. Silicone sealants are generally recommended for usewith LEXAN Thermoclear sheet, see Figure 22, but it is strongly advised when using non GE sealing compounds to check compatibility before use.

Compatible Neoprene, EPT or EPDM rubbers with an approxi-mate Shore Hardness of the A65 are generally acceptable andcompatibility reports for different rubber types are availableupon request.

In case of doubt about any aspect of the chemical compatibility of the LEXAN Thermoclear sheet range, alwaysconsult your nearest GE Structured Products Sales Office forfurther advice.

Fig. 22

* Registered trademark of Norton Company.

10

G e n e r a l g u i d e l i n e sLEXAN® Thermoclear® sheet should be stored and protected againstatmospheric influence like sun, rain

etc. LEXAN Thermoclear sheets of the same length should bestacked together horizontally or, if different length, graded withthe longest sheet at the bottom of the stack in order to avoidunsupported overhang. The stacks should be supported on timber bearers. Do not stack where they can be walked on ordriven into.

As with all glazing materials, careshould be exercised when handlingand transporting LEXAN Thermoclear

sheet in order to prevent scratches and damage to sheetedges. Each sheet is packaged as follows to minimize the riskof these problems.

• Top face covered with a printed masking. This isthe UV protected side and should face outwards.

• Bottom face with a plain white masking.• Edges with a colored protective edge tape,

retain in packed condition until immediately priorto installation.

LEXAN Thermoclear sheet can usually be cut easily and accuratelywith standard workshop equipment.

This includes common circular, hand and hacksaws. Saw dustshould be blown out of the channels using clean compressedair. Circular saw blades should be fine-toothed panel blades.When hand or power hacksaws are used, the sheet should be clamped to the worktable to avoid undesirable vibration.When finished the edges of LEXAN Thermoclear sheet shouldbe free of notches and swarf build-up.

With the smaller wall section LEXAN Thermoclear sheetgrades (up to 10 mm) it is possible to cut the sheet with aknife. However, it is important that the knife is sharp.

Holes should be drilled either by ahand or power drill using a metalworking bit. When drilling, support

should be given immediately beneath the drill to avoid vibration. Very clean holes are easily obtained. The use of liquid cooling media is not recommended.

Since LEXAN Thermoclear sheet has a greater linear thermal expansioncoefficient than traditional glazingmaterials, care should be taken toallow for free expansion of the sheet

to prevent bowing and internal thermal stress:

Thermal expansion allowance must be made for both thelength and width of the LEXAN Thermoclear sheet. The recommended allowances for various sheet dimensions areoutlined in the graph. The sheet must be trimmed at least asmuch as the indicated thermal expansion.

In general: Thermal expansion of the sheet is approximately.140 inch per linear 39 inches.

On roof constructions LEXANThermoclear sheet should not beused to support a person’s weight

during installation or cleaning. A temporary wooden beam orother device, supported by the roof members, should alwaysbe used.

Storage

Handling

Sawing

Drilling

Pre-installationThermal ExpansionAllowance

Site Safety

Sash dimension in inches

Tota

l the

rmal

exp

ansi

on in

inch

es

20 39 59 79 98 118 138 157 1770

.039

.079

.118

.159

.197

.236

.315

.394

.47

.276

.354

.43

.51

.55

.59

Fig. 24

Fig. 25

Fig. 26

Based on Temperature Change of 100˚F

11

LEXAN® Thermoclear® sheet should be mounted with the ribs runningdownwards to assist in condensation

water drainage. Algae growth, in the form of a green depositinside the sheet channels, may occasionally be a problem. It isthe result of permanent condensation inside the channels dueto particular temperature conditions. Steps to help prevent condensation and algae formation are discussed in more detailin Section: Sealing Techniques.

Note: The tape delivered on Thermoclear sheet is for protection only and is not an impermeable sealing/installation tape. Thistape should be replaced prior to installation with a tape asdescribed in section: Sealing Techniques. Before installation,remove approximately 2 inches of the masking from all sheetedges. Only remove the remaining masking when the installation is complete.

Glazing with LEXAN Thermoclear sheet should be considered a finishing operation and seen as the final step in the completion of an application.

P re - I n s t a l l a t i o n / S e a l i n g G u i d e l i n e sPre-installation

•The tape should have a good weathering resistance, without loss of adhesion or mechanical strength over a long period.

• The tape should have good resistance to tearing and otherdamage during installation and handling.

• Multifoil has developed G3629, an antidust impermeabletape, and AD3429, an antidust venting tape. By way of“Verzekered Keur” Multifoil will provide within Europe a 10 Year Guarantee on the operation of the tapes.

MULTIFOILUS Dealer:

International Trading Partners, Ltd.1413 Sharps Point RoadAnnapolis, MD 21401410-757-5040Europe Dealer:

Verl. Hoogravenseweg 63 h3252 BB Utrecht, NLThe Netherlands:

tel. +31 30 28 96 333fax. +31 30 28 94 545

Basic RequirementsSealing Tape

One of the most important aspects ofinstallations is edge sealing, particu-larly the open-ended channels, since

moisture build-up and dust contamination inside the channelscan be a major problem. There are several techniques that canbe adopted to significantly reduce contamination, the choicedepending largely on the prevailing environmental conditions.

Sealing Techniques

The following guidelines are recommended to minimize sealing and contamination problems:

• Ensure that all sheet edges are smooth androunded before applying the tape.

• All channels should be blown free of dust beforesealing.

• Ensure tape is completely covered by glazingprofiles, flashings, end closures etc. No tapeshould be left exposed when installation iscomplete.

• Replace any damaged tape before finalinstallation.

• Suitable and approved sealing tapes for glazing LEXAN Thermoclear sheet, are available at the vast majority of approved LEXAN Thermoclear sheet distributors and specialized installers.

Sealing guidelines

Both channel ends sealed with impermeable tape, e.g. Multifoil G3629 tape.Recommended for use in:

• Extremely dusty environments (sawmills - welding-stations, etc.).

• Low humidity/dry conditions (shopping centers -warehouses, etc.).

• No interior/exterior temperature difference(football stadium - metro/railway station roofing).

No dust/insect penetration.• Possible water build-up in channels by

condensation.• Risk of algae growth.

Glazing-SpecificEnvironments

Sealing recommendation

Fig. 27 Impermeable tape on both sides

Remarks

12

P re - i n s t a l l a t i o n - S e a l i n g Te c h n i q u e sTop end channels sealed with animpermeable tape, e.g. Multifoil G3629 tape. Bottom end channelssealed with a perforated filter tape,

e.g. Multifoil AD 3429 tape.

Additional `U’ profile covering perforated bottom tape, or distance holders between venting holes to facilitate condensation drainage. See fig. 31 and 32.• Integrated filter which minimizes dust/insect penetration.• Condensation water drainage possibility.• Ventilation into channels helping to prevent

excessive condensation.• Clearance between bottom sheet edge and sash

platform necessary to allow for condensation drainage.

At semicircular barrel vaults both channel ends should besealed with perforated filter tape, e.g. Multifoil AD 3429.

General StandardGlazing Conditions

Care should be taken to provide a clearance between bothsheet edges and sash platform to allow for condensationdrainage. See figs. 31 and 32.

The following recommendationsapply to installations involving flatglazing, i.e. vertical, horizontal orinclined, and curved glazing. It is

extremely important when installing LEXAN Thermoclearsheet that the edges are correctly clamped, whether the application involves wet or dry glazing conditions.

A cover plate, or glazing bead, with rubber gaskets or siliconesealant, can hold the sheet in place and create a watertightseal. In both cases there must be sufficient clearance to allowfor thermal expansion of the sheet. It is also important that theedge of the sheet be engaged for a minimum of 3/4" into theglazing frame with at least one rib located in the clampingarea. See fig. 33.

Sheet edgeClamping Conditions

Fig. 28

Fig. 29

Fig. 30

Fig. 31

Fig. 32

Impermeable tapePerforated tape

‘U’ profile

perforated filter tape

condensed water drainage

perforated filter tape

distance holder, e.g. rubber/filter tape

13

G l a z i n g S y s t e m s

In general the total rebate depth for each profile shouldinclude a minimum of .3/4 inch engagement and an allowancefor thermal expansion. Due to the rib geometry of 16 mmLEXAN® Thermoclear® sheet, additional precautions shouldbe taken. In this case it is important that the sheet is cut sothat at least one rib is located in the center of the rebate.

This selection illustrates some glazing proposals using commerciallyavailable profiles which have beensuccessfully used in combination with

LEXAN Thermoclear sheet. Situations may occur where sheetexpansion exceeds sealant limitations and often for aestheticreasons, this type of “dry” glazing system can provide anideal solution.

The advantage of dry systems is that the rubber gaskets are `snapped’ into the glazing strips which then allow freemovement of the sheet during expansion and contraction. See figs. 34 and 35.

WARNING!Do not use P.V.C. gaskets!

Due to migration of additives of soft P.V.C., the LEXANThermoclear sheet can be chemically affected resulting in surface cracks or even sheet breakage.

A wide range of easy to use glazing bars and fixing acces-sories, designed specifically for glazing LEXAN Thermoclearsheet, are available at the vast majority of approved LEXANThermoclear sheet distributors and specialized installers.

Dry Glazing Systems

This type of installation system is mainly used in small domestic type applications: car ports, ware-houses, conservatories and other

glass replacement situations.

With standard metal profiles or wooden sections, in combina-tion with glazing tapes and glazing compounds, many different configurations are possible. See figs. 36 and 37.

When using glazing compounds it is essential that the sealantsystem accepts a certain amount of movement, to allow forthermal expansion, without loss of adhesion to the frame orsheet. Silicone sealants are generally recommended for usewith LEXAN Thermoclear sheet, but it is strongly advised whenusing sealing compounds to check compatibility before use.

Care should be taken not to use amino or benzamid curing silicone sealants, which are not compatible with LEXAN® sheetand result in micro-cracks, particularly when stress is involved.See fig. 22 for sealant recommendations.

Wet Glazing Systems

Fig. 33 Fig. 35

Fig. 34

Fig. 36

Fig. 37

14

W i n d & S n o w L o a d i n gThe wind speed is used to determinethe actual loading upon the glazingpanels. In mathematical terms, thepressure loading is calculated by

multiplying the square of the design wind speed by 0.002531

q = KV2

where q = dynamic wind pressure in lb - force/ft2

K = 0.002531V = design wind speed in mph

To allow for local fluctuations in theacceleration/deceleration of the windby building or glazing geometry, it is

necessary to include an appropriate pressure coefficient. Thewind loading is obtained by multiplying the dynamic windpressure by the pressure coefficient. Detailed pressure coefficient values can be found in the appropriate NationalBuilding Norms.

Snow loadings on roof glazings shall be considered equivalent to a vertically, uniformly distributed

load, acting per ft2 of the horizontal projection of the glazing.Snow loading factors can be obtained from the appropriatelocal building norm.

A computer aided design programhas been developed especially forlarge glazing projects, or projects with an uncommon shape or unusual

loading conditions. The problem creates the finite elementmodel of a particular glazing design, applies the specifiedloads and edge condition and runs the deflection analysis.Consult your nearest GE Structured Products Technical Service Center for further advice.

Support Conditions

Note: Regardless of support configuration selected, the sheetshould always be installed so that the rib structure channelsare sloping downwards. Sheet “width” is the dimension perpendicular to the rib structure, “length” the dimension parallel.

Safety factor

The tables indicate the maximum allowable sheet at a speci-fied loading which results into an acceptable sheet deflectionbehavior while minimizing the RISK of sheet buckling or pop-out effect calculated with a safety factor of 1.5.

N.B. The values indicated in the tables are applicable for aLEXAN Thermoclear sheet edge engagement in the glazingframe of at least .75 inches.

General Comments

For sloped glazing applications a minimum slope of 5°(1 in/1 ft sheet length) is advised to allow for rainwaterdrainage.

Dynamic WindPressure

Pressure Coefficient

Snow Loading

Values of q in SI units (lb-force/ft2)

windspeed windpress windspeed windpressmph lb-f/ft2 mph lb-f/ft2

20 1.04 150 5630 2.50 170 7250 6.0070 12.00

100 25.00120 36.00

For glazing projects with an unusual loading condition, please contactyour local GE Structured Products Sales Office.

Computer aidedSheet Engineering

Sheet ThicknessCriteria andTable Interpretation

sheet edgeengagement ±3/4 inch

Fig. 38

Fig. 39

Fig. 40

15

T h i c k n e s s S e l e c t i o n F o r F l a t G l a z i n gBecause of LEXAN® Thermoclear® sheet’s exceptional stiffness to weight ratio, it is ideally suited for load bearingapplications such as vertically installed or sloped glazing.

The following information has been generated to assist the designer in selecting the proper gauge, sheet size and support spacing for their applications.

The design information has been organized in graph formbased on fixed widths of 24", 36", 48", 72", and 83". In allcases, the ribs are running perpendicular to the width. The data has been further organized according to allowabledeflection limits. Select the maximum design deflection and choose the graph having the proper width dimension.Then plot, starting from the specified design load (PSF) across the Y axis to the maximum deflection desired. The recommended maximum unsupported sheet length is located at the intersection.

16

17

18

19

20

21

LEXAN Thermoclear sheet can be successfully cold curvedover curved support glazing profiles, to suit many glazingapplications, e.g. domes, rooflights etc. Providing the radius is not below the minimum recommended value of 175 timesthe thickness, then the introduced stress by cold curving is not expected to have any adverse effect upon the mechanical performance of the sheet. Sheets must always be bent longitudinally, never across the width of the sheet.

The minimum radius values are outlined below in fig. 51.

The following load charts are based upon curved glazingapplications clamped on all four edges. The charts show linear buckling load values (calculated with a safety factor of2.0) against installation radii.

Sheet length ‘L’ needs to be greater than sheet width ‘W’ tofacilitate curvature; in practice, a ratio of 1:2 or less is virtuallynever contemplated because of the practicalities of installationgeometry.

C u r v e d G l a z i n g S y s t e m s / S h e e t T h i c k n e s s S e l e c t i o n

How to read the charts.

Curved Glazing

The design information in the following pages is organized ingraph form for each thickness of Thermoclear and is based onthe cold formed glazing radius and the specified design load.To determine the required rafter spacing, find the graph thatrepresents the desired sheet thickness and locate the line onthe graph that represents your loading requirement startingfrom the design radius fixed on the X axis, plot up to the line that represents the specified loading and locate your maximum rafter spacing on the Y axis.

center to center distance betweencurved support rafters

radius 'R'

span

LEXAN Thermoclear Min. Radiussheet thickness inches

6 41

8 55

10 69

16 110

20 138

25 173

Fig. 51

Fig. 50

90

80

70

60

50

40

30

20

10

041 47 51 55 59 63 69 74 78 82 86 90 94 98

LTC2R6

RADIUS, inches 12.5psf 16.5psf 21psf 25psf29psf 33psf 37psf 41psf

Uniform Loading

Rafte

r Spa

cing

in In

ches

22

90

80

70

60

50

40

30

20

10

055 59 63 69 74 78 82 86 90 94 98 102 106 110 118 126

LTC2R8


Uniform Loading

Rafte

r Spa

cing

in In

ches

90

80

70

60

50

40

30

20

10

069 74 78 82 86 90 94 98 102 106 110 118 126 134

LTC2R10


Uniform Loading

Rafte

r Spa

cing

in In

ches

90

80

70

60

50

40

30

20

10

0110 118 126 134 142 150 158 166 174 182 190

LTC3T16


Uniform Loading

Rafte

r Spa

cing

in In

ches

23

L E X A N T h e r m o c l e a r S h e e t G l a z i n g G u i d e l i n e s

General

• Clean window frame. Remove old putty or broken glass, ifnecessary.

• Measure sheet edge engagement area (± .75 inch) andinternal window frame dimensions, i.e. the space intowhich the LTC sheet will be fitted.

• Calculate sheet size, allowing clearance for thermal expansion (.118 inch per linear 39 inches).

• Select right LTC type, which fulfills loading requirements, U-value, etc.

• Clamp the LTC sheet to a support table to avoid vibrationand rough cutting.

• Cut the sheet to required size, using a standard electric circular or jig saw.

• Blow out the saw dust contaminated channels with cleancompressed air.

• Remove any sharp edges and irregularities from the sheet.

• Peel back approximately 2 inches of masking film from all 4 edges of the cut sheet on both sides.

• Select appropriate sealing tape by an accurate considera-tion of glazing application.

• Seal the top and the bottom sheet channels with imperme-able and/or venting tape, i.e. Multifoil G3629/AD 3429.

Please refer to the processing instructions provided by thesealing tape supplier.

• In case of venting tape, and to allow condensed waterdrainage, apply an aluminum closure profile with drainagepossibilities or apply some single sided self adhesive glaz-ing tape as distance holder between the venting holes.

• For wet glazing apply single sided self adhesive glazingtape or rubber profile to both window frame and bead.

• For dry glazing, snap-fit neoprene rubber gaskets in place insupport profile as well as in clamping cover profile.

• Insert the LEXAN Thermoclear sheet into the windowframe.

• LEXAN Thermoclear sheet should always be installed with the ribs running vertically and the UV protected sheetsurface should always face outwards.

• Fix window bead or clamping cover profile in place.

• For wet glazing apply appropriate silicone sealing compound, i.e. Silglaze/Silpruf sealants between sheet andwindow frame/bead.

• Remove all masking film immediately after installation.

• Clean window carefully with warm soapy water and softcellulose sponge or woolen cloth.

Don’t s

• Do not use plasticized PVC or incompatible rubber sealingtapes or gaskets.

• Do not use amine, Benzamide or Methoxy based sealants.

• Do not use abrasive or highly alkaline cleaners.

• Never scrape LEXAN Thermoclear sheet with squeegees,razor blades or other sharp instruments.

• Do not walk on LTC sheet at any time.

• Do not install LTC sheet with damaged tapes.

• Do not clean LTC sheet in hot sun or at elevated temperatures.

• Benzene, gasoline, acetone, carbon tetrachloride or butylcellosove should never be used on LTC sheet.

Wet Glazing Dry Glazing

Metal frame Glazing filler tape

Silicone sealant

Fig. 53 Fig. 54

24

® Registered Trademarks of General Electric Company.™Trademark of General Electric Company.SPL-2315B (6/00) Ryba

gGeneral Electric CompanyOne Plastics AvenuePittsfield, MA 01201

GE Structured Products

The technical support you need and deserve.

Our growing portfolio of GE StructuredProducts incorporates diverse technologies from the industry’s mostcomprehensive engineering plasticsline. Our film and sheet technology isonly matched by the quality of technicalassistance that’s available to you—frominitial concept and design through fabrication and end-use.

To optimize the use of GE StructuredProducts materials, please call:(800) 451-3147 or (413) 448-5400.

For Customer Service assistance, pleasecall: (800) 323-3783.

Although all information, recommendations, or advice contained here-in is given in good faith, no guarantee is made that the same results asthose described will be obtained or as to the effectiveness or safety ofany design, and General Electric Company, USA, its subsidiaries, affili-ates and authorized representatives shall in no event be held responsi-ble for any loss incurred through such use of the products. Each usershall make its own determination of the suitability of the products orany such information, recommendations or advice for its own particu-lar use. The products of General Electric Company, its subsidiaries oraffiliates are sold in any event subject to the Conditions of Sale consti-tuting part of the applicable representative or other sales agreement orprinted on the back of order acknowledgments or invoices or are avail-able upon request. Nothing in this or any other document or any oralrecommendation or advice shall be deemed to alter, vary, supersede, orwaive any of the Conditions of Sale. Statements concerning possible orsuggested uses of the materials or designs described herein are not tobe construed as constituting a license under any General ElectricCompany or subsidiary or affiliate company patent covering such useor as recommendations for use of such materials or designs in theinfringement of any patent.

GE Structured Products United StatesGE Plastics1 Plastics AvenuePittsfield, MA 01201(413) 448-5400

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CanadaGE Plastics - Canada2300 Meadowvale Blvd.Mississauga, OntarioCanada L5N 5P9(905) 858-5774

GE Structured Products LEXAN Thermoclear Multi-wall Polycarbonate

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