Glazing TABLE OF CONTENTS FOREWORD... 1 PUBLICATION... 1 REFERENCE STANDARDS GLAZING CLASSIFICATIONS... 3 Type I Type II Type III

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1 TABLE OF CONTENTS Glazing TABLE OF CONTENTS FOREWORD PUBLICATION REFERENCE STANDARDS GLAZING CLASSIFICATIONS Type I Type II Type III LIGHT TRANSMISSION Phtsynthetically Active Radiatin Ttal Slar Radiatin Haze and Luminus Transmittance Near Infrared Transmissin Medium/Far Infrared Radiatin ASTM E ENERGY U-Value STRENGTH Hail Resistance Tear Resistance Wind Lad LONGEVITY Type I Strength Slar Light Transmissin Type II Current Text Lad Glazing System Design & Safety Type III Strength Slar/Par Transmissin COMBUSTIBILITY MISCELLANEOUS CHEMICAL AND MATERIAL COMPATIBILITY i

2 GENERAL Natinal Greenhuse Manufacturers Assciatin 1986 (2004) GLAZING STANDARD GUIDELINES & VOLUNTARY STANDARD TEST METHODS FOREWORD The NGMA, having received cmment frm grwer and residential purchasers f glazing materials regarding the vagueness, cnfusin and lack f standard test methd citatin in the public advertising f glazing perfrmance, has prmulgated the Glazing Standard. It cvers recmmended test methds frm heat transfer, light transmissin, lngevity, and resistance t hail, tearing, wind lad and cmbustibility. The use and results reprting f the recmmended test methd shall be vluntary n the part f glazing manufacturers, greenhuse manufacturers r glazing resellers. Sme manufacturers may prefer ne test methd ver anther. A few tests are mandatry depending n the industry and applicatin. The vluntary NGMA Standard is published with the fficial recmmendatin f NGMA in rder that Architects, engineers, greenhuse manufacturers, cnsumers and grwers may request glazing perfrmance measurements based n this standard and that glazing manufacturers vluntarily cmply with thse requests. Nthing cntained herein shall be cnstrued as a mandatry requirement (i.e., as a basis fr NGMA membership) and n cmments r statements herein shall be cnstrued t imply that nly ne type, shapes, frm r material cntent f glazing is preferred ver anther nr that any brand names assciated with NGMA membership are preferred ver ther member s brands r nnmembers brands PUBLICATION This standard is the prperty f and published by the natinal Greenhuse Manufacturers Assciatin, a nnprfit grup dedicated t the cntinued grwth f cntrlled envirnment hrticulture in the U.S.A... This standard may be amended frm time t time and the dates f all revisins shall be identified at the end f this Paragraph April 1990 (April 2004) 1

3 REFERENCE STANDARDS Glazing REFERENCE STANDARDS (In this Publicatin) ASTM C-158 ASTM C-236 ASTM D-256 ASTM D-265 ASTM D-568 Methd fr Flexure Testing f Glass (Determinatin f Mdulus f Rupture). Test methd fr steady-state thermal perfrmance f building assemblies by means f a guarded ht bx. Test methd fr impact resistance f plastics and electrical insulating materials. Test fr Impact using Gardner Impact Methd. Test methd fr rate f burning and /r extent f burning f Flexible plastics in a vertical psitin. ASTM D Test methd fr rate f burning and/r extent f burning f self supprting plastics in a hrizntal psitin. ASTM D-638 Test fr Plastics Tensile Strength, Elngatin, and Tensile Mdulus. ASTM D-696 Test methd fr Cefficient f linear thermal expansin f plastics. ASTM D-79 Test methds fr flexural prperties f un-reinfrced and reinfrced plastics and electrical insulatin materials. ASTM D-882 Test methd fr tensile prperties f thin Plastics sheeting. ASTM D-1003 Test methd fr haze and luminus Transmittance f transparent plastics. ASTM D Test Methd fr Impact resistance f Plyethylene film by the free falling dart methd. ASTM D-256A Test methd fr Impact resistance f thermplastics recrding IZOD impact values. ASTM D Test methd by prpagatin f resistance f Plastic film and thin sheeting by pendulum methd. ASTM D-1925 Test fr yellwness index f plastics. ASTM D-1929 Test methd fr ignitin prperties f plastics. ASTM D-2843 Test methd fr density f smke frm the burning r decmpsitin f plastics. ASTM D-3763 Test methd fr high speed punctures prperties f plastics using lad and displacement sensrs. ASTM D EMMAQUA practice fr perfrming accelerated utdr weathering f plastics using cncentrated natural sunlight. ASTM E-84 Test methd t determine Smke density and Flame spread ratings Similar t UL-723, ANSI N. 2.5, NFPA N 255 and UBC 42-1 ASTM E-72 Methd fr cnducting strength f panels fr building cnstructin. ASTM E-167 Recmmended practice fr Gniphtmetry f bject and materials. ASTM E-330 Test Methds fr structural perfrmance f exterir windws, curtain walls and drs by unifrm static air pressure difference. ASTM E Test Methd fr Slar Energy Transmittance and Reflectance (Terrestrial) f Sheet Materials. ASTM E (2003) Practice fr determining resistance f slar cllectr cver t hail impact with prpelled ice balls. ASTM E-831 Test Methd fr linear thermal expansin f slid materials by Therm chemical Analysis. ASTM E Test methd fr slar absrptance, reflectance and transmittance f materials using integrate spheres. ASTM E Standard Practice fr calculatin f Phtmetric transmittance and reflectance f materials t slar radiatin. ASTM E Standard Test Methd fr Slar Phtmetric transmittance f sheet materials using sunlight. ASTM E Standard Test Methd fr Slar Transmittance (Terrestrial) f sheet materials using sunlight. ASTM E Test methd fr determining slar r phttrphic reflectance and absrptance f materials using a large diameter integrating sphere. ASTM E Standard Test methd fr perfrmance f Exterir Windws, Curtain Walls, and Strm shutters Impacted by Missile/s and expsed t Cyclic Pressure Differentials. ASTM E Standard Specificatin fr Perfrmance f Exterir Windws, Curtain Walls, Drs and Strm Shutters Impacted by Windbrne Debris in Hurricanes. ASTM G-26 Recmmended practice fr perating light expsure apparatus (xenn-arc type) with and withut water fr expsure f nn-metallic materials. UL94 Test fr Flammability f Plastic Materials fr Parts in devices and appliances. 2

4 CLASSIFICATIONS & LIGHT TRANSMISSION GLAZING CLASSIFICATIONS Because varius glazing materials have radically different respnse t envirnmental cnditins such as slar irradiance, wind, snw, and hail; and are by virtue f cmpsitin and manufacturing parameters quite different in physical prperties, NGMA has elected t describe three different categries f glazing: Type I Thin films, generally ranging frm 2-8 mills ( ) nrmally duble layer, air inflated Plyethylene, EVA (ethylene vinyl acetate), plyvinyl chlride (PVC), plyvinyl fluride and plyester films fall int this categry. Type II Flexible plastics such as fiberglass reinfrced plastic (Thermset Plyester (FRP), acrylic, plycarbnate, plyprpylene, PVC, and PETG panels and the ladder prfile ( Multiwall ) type structured materials such as plycarbnate, acrylics, Plyprpylene, PETG and laminar cmpsites f bth (any). This includes the fllwing: Flexible Thermplastics Multiwall Acrylic Sheet Mnlithic Acrylic Sheet Crrugated Acrylic Sheet Duble & Multiwall Plycarbnate Sheet Mnlithic Plycarbnate Sheet Crrugated Multiwall Plycarbnate Sheet Crrugated Mnlithic Plycarbnate Sheet Mnlithic PETG C-Plymer (Glycl mdified Plyester Terephthalate) Multiwall Plyprpylene Sheet Mnlithic PVC Sheet Flexible Thermset Plyester Plastic Sheet (Glass Reinfrced FRP) Mnlithic fiberglass sheet Crrugated fiberglass sheet Cmpsites Cmbinatins f Glazing plastics laminated t each ther Cmbinatins f Glazing plastics laminated t Glass TYPE III Rigid Materials Glass: Flat Glass, annealed, chemically strengthened, tempered and laminated frms f flat, annealed, chemically strengthened, tempered, and rlled patterned glass LIGHT TRANSMISSION PHOTOSYNTHETICALLY ACTIVE RADIATION Applicable t Types I and II and III, Phtsynthetically Active Radiatin (PAR) is the visible prtin f the (light) spectrum frm nanmeters and is regarded by many hrticulturists as being critical fr plant grwth and develpment Cmparative analysis f glazing materials light transmitting prperties must take int cnsideratin the number f layers f glazing invlved fr all three types. Single layer glazing generally will have smewhat higher slar transmissin than multiple layer glazing. 3

5 LIGHT TRANSMISSION Glazing Fr cmparing ptential plant grwth, NGMA recmmends that glazing manufacturers test and reprt the PAR data derived frm the fllwing test prcedure/s. Light Transmissin is measured ver the spectrum frm nanmeters, which includes the PAR range. The Prcedure prvides a methd t determine the weighted average transmissin ver this range. Testing and reprting shuld be perfrmed accrding t the prcedures specified in ASTM E and/r any f the apprpriate prcedures listed belw;(astm E Standard Test methd fr determining Slar r phttrphic Reflectance f materials Using a large Diameter Integrating Sphere. Testing shuld be perfrmed at incidence angles f 0, 45 and 60 ). NGMA recmmends ASTM and ne r any f the prcedures listed belw apprpriate fr the material substrate (ASTM E-1175 measurements) fr cmparisn f new materials in Type I, Type II r Type III. Light Transmissin values f aged materials will vary widely based n expsure cnditins. {see LONGEVITY sectins} TOTAL SOLAR RADIATION Slar irradiance applicable t Types I, II, and III includes the entire energy spectrum created by the sun. It includes the majr energy carrier in the near infrared waveband and is useful in calculating ttal energy gain in a greenhuse s that heating and cling requirements can be calculated. ASTM E-903 prvides this data and ASTM E-891 the calculating prcedure. HAZE AND LUMINOUS TRANSMITTANCE Haze, the percentage f transmitted light that deviates frm the incident beam by frward scattering and luminus transmittance, the rati f transmitted light t incident light may be pertinent t a grwer s verall evaluatin f a glazing system. The prcedures f ASTM D-1003 shuld be used t determine these values applicable t Type I and II. The prcedures f ASTM E-903 shuld be used t determine the values applicable t Type III. NEAR INFRARED TRANSMISSION Near Infrared energy is the thermal slar radiatin, which adds t the heating f the greenhuse. The infrared transmissin frm mm is measured by prcedures specified in ASTM E-903. MEDIUM/FAR INFRARED RADIATION Far infrared energy is the energy, which is reprduced by the (Thermal) mass inside a greenhuse. Transmissin f far infrared energy thrugh a greenhuse cvering affects the heat retentin capability f a greenhuse. 5 t 20 micrns is the range f imprtance and 7 t 14 micrns is the mst critical area f that range as measured by prcedures specified in ASTM E-903 mdified. ASTM E Standard Test Methds fr Slar Energy Transmittance and Reflectance (Terrestrial) f Sheet Materials American Sciety fr Testing and Materials, 1916 Race St, Philadelphia PA , June 1971 PROCEDURES ASTM Standard test methd fr Slar Absrptance, Reflectance, and Transmittance f Materials using Integrating Spheres ASTM E Standard Test Methd fr slar Transmittance (Terrestrial) f sheet materials using sunlight ASTM E Standard practice fr calculatin f Phtmetric transmittance and reflectance f materials t slar radiatin ASTM E Standard Test Methd fr Slar phtmetric transmittance f sheet materials using sunlight. ASTM E Standard Test Methd fr Determining Slar Phtpic Reflectance, Transmittance r absrptance f materials using a Large diameter integrating sphere ASTM E-1003 Standard Test Methd fr measuring Haze, Luminus & Transmittance f Transparent Plastics 4

6 ENERGY& STRENGTH LIGHT TRANSMISSION (REVIEW) Visible Light Radiatin Slar Radiatin ASTM D-1003 ASTM E Light Transmissin Direct Slar Transmissin %ST Light Reflectin Slar Reflectin %SR Light Absrptin Slar Absrptin %SA Ttal Slar Transmissin % STt Ttal Slar Reflectin % SRt Shading Cefficient SC ** This adds in a big way: ASTM E as a Reference Standard primary r alternate as acceptable testing criteria. ENERGY U VALUE Applicable t Types I, II, and III (glazing): where U=Rt equals the sum f the R Values. This is the verall rate f heat r Energy Transfer; the lwer the abslute value, the mre resistance t heat transfer, R-Value is reciprcal (=1/U) and is cmmnly used in cnsumer advertising where the R-Value is the resistance t heat transfer. The higher the R- Value f a glazing material the mre resistant it is t heat transfer. Natinal Greenhuse Manufacturers Assciatin recmmends that U values be calculated and reprted fr all glazing materials. Summer and winter values are t be reprted, with shading cefficient t be included in summer value. Shading cefficients can be calculated using the ASHRAE frmula. NOTE: Air infiltratin is a significant factr in heat lss, but is nt a part f ASHRAE U-Value calculatin prcedures. Ttal glazing systems may vary widely in air infiltratin and grwers are cautined t include air infiltratin heat lss in their verall assessment f energy lss (gain). STRENGTH HAIL RESISTANCE Type I A.) NGMA recmmends ASTM D Standard test methds fr Impact resistance f Plastic Films by the free falling dart methd, Using Methd A Type II & Type III A.) NGMA recmmends ASTM E (2003) Standard Practice fr determining Resistance f Slar Cllectr Cvers t Hail by impact with prpelled ice balls. Nine values will be reprted using three sizes f 1", 1 1/2" and 2" at three speeds f 50, 60, and 70 mph.). B.) NGMA recgnizes as vluntary: ASTM E Standard Specificatin fr Perfrmance f Exterir Windws, Curtain Walls, Drs and Strm Shutters Impacted by Windbrne Debris in Hurricanes as als demnstrating the impact value f Type II & Type III materials fr large and small missile impact including hail. C.) NGMA recgnizes as vluntary: ASTM E Standard test methd fr perfrmance f Exterir Windws, Curtain Walls, and Strm Shutters Impacted by Missile(s) and expsed t Cyclic Pressure Differentials as als demnstrating impact and deflectin capabilities f Type II & III materials under cyclic wind pressure. 5

7 LONGEVITY Glazing TEAR RESISTANCE Type I A.) NGMA recmmends ASTM D Standard Test Methd fr Prpagatin f Tear resistance f Plastics Film Sheeting by Pendulum Methd. WIND LOAD Wind lad resistance is usually mre a functin f structural integrity than glazing strength. Grwers are urged t refer t the NGMA Standard fr Greenhuse Structures, apprpriate building cdes, manufactures literature and the unique aspects (mechanical prperties) f the glazing material hlding film (r glazing system hard cver) LONGEVITY (TYPE I, II, & III THE BASICS) The usable life f glazing (skinning) materials is defined as the number f mnths r years that a material will functin effectively in a cmmercial grwing applicatin. T functin effectively, it must retain sme prtin f its essential prperties (mechanical, physical, thermal and electrical) f strength and inherent light transmissin (that part wing t internal chemical change as ppsed t that wing t external factrs such as accumulated dust. dirt and the effects f crrsive atmspheres (internal & external). In sme materials, the decrease in light transmissin, nt lss f physical strength determines the useful life f the glazing material. Type I materials; (NGMA recmmends utdr weathering test fr) Type I shuld be tested with actual utdr weathering. DSET Labratries facilities, Atlas Weathering Service Grup, at their headquarters in Arizna is the (an) NGMA apprved test center fr actual utdr weathering. ASTM D Standard Practice fr perfrming Outdr Accelerated Weathering tests f Plastics Using Cncentrated Sunlight is applicable t a range f plastics materials including, but nt limited t plastic films, sheets, laminates and extruded and mlded prduct in a variety f selected sizes. The claiming f specific useful life f a glazing shall be based n a well defined actual utdr expsure r by crrelatin between results f an accelerated weathering prcedure and actual utdr weathering. The nly currently acceptable accelerated weathering test fr Type I & Type II materials is ASTM D-4364 EMMAQUA. The same testing prcedure used fr determining the strength and light transmitting prperties f a given material shuld be used t determine the strength f the weathered material. Test cmparisn fr strength shall nt be made between material types. Strength values are nly valid fr the verall evaluatin f a glazing material fr a given applicatin. TYPE I STRENGTH: Fr Flexible Films, the strength shall be cnsidered inadequate when the elngatin t Break has decreased t 50% f the riginal value. The recmmended test methd is ASTM D-882, METHOD A. SOLAR/LIGHT TRANSMISSION: Slar/Par values t cntrls and weather samples shall be measured by ASTM E-903 and shall be cmpared t determine the lss fr a given perid f time (example: 1yr, 3 years, 10 years) 6

8 LONGEVITY TYPE II (Strength f TYPE II Materials) CURRENT TEXT The strength and cntrl f weathered samples shall be measured by any (ne r mre) f the fllwing prcedures. The sample thickness shall be (1/8 ) (r perfrmed in the same thickness fr intended use) fr the apprpriate tests, and where applicable, the side that is expsed during the weathering is the side put under tensin (r impacted using an apprpriate test prcedure) 1.) Tensile Strength, Elngatin, Tensile Mdulus ASTM D ) Flexural Strength ASTM D ) Flexural Mdulus ASTM D ) Impact Resistance ASTM D-265 Gardner Impact 5.) Hail Resistance ASTM E ) Impact Resistance ASTM D-3029 Methd 7.) Deflectin temperature under flexural lad ASTM ) Specific Gravity ASTM D ) Cefficient f Thermal Expansin ASTM-696 NOTE: We can als include new ASTM s fr High Impact IE Dade Cunty & Hurricane. NOTES: Type II Materials Wind, Dead, Live Lading & Design 1.) Wind, dead, live lad resistance being the design functin f the structural integrity f a greenhuse substructure, each Type II glazing plastic material has unique prperties (tested in accrdance with the prcedures listed) which must meet lcal building cde fr lad and fr flammability. The NGMA recmmends a thrugh review f all glazing manufacturer s literature and warranties t include but nt be limited t the fllwing: A.) LOAD Review thickness, width, and length cnsideratins fr flat and/r cld curved glazing pertaining t the material f chice. Glazing manufacturer printed literature, engineering tables, and cpies f actual testing results shuld be applicable fr bth psitive and negative lads fr all structures. Sheet installatin is expressed in terms f width, gauge, & length fr glazing bar and purlin distance recmmendatins. Since sme Type II materials require fastening t accmmdate negative requirements lading cnsult glazing materials manufacturer guidelines fr fastener type, dimensin, and cmpsitin. Since Type II materials are used n pened rf and vented structure applicatins, negative lading cnditins must be cnsidered. Pint fastening materials- selectin & methd f installatin/attachment fr flat and cld curved greenhuses must be cnsidered. Negative lad failure ccurs when part f r entire sheet/s is frced (detached) frm the structure. The fasteners must be f sufficient area (diameter) f cntact, number and placement t prevent this type f failure. Materials cmpatibility Wet sealants & dry gaskets and sealing tapes which cme int cntact with the glazing prduct must be cmpatible with the cmpsitin f the glazing. Incmpatible materials lead t stress failure under lad and weathering. Pre and pst installatin guidelines, sheet preparatin and cleaning instructins fr ne and tw sided UV prtective glazing materials shuld be nted and expressly fllwed. 7

9 COMBUSTIBILITY Glazing B.) GLAZING SYSTEM DESIGN & SAFETY: Since Type II glazing materials deflect t sme degree under lad: TYPE III Edge bite and expansin clearance prvided by glazing systems are primary design criteria s. Glazing material manufacturers shuld indicate by written r graphic illustratin glazing system design requirements and recmmendatins fr their prduct Tw side glazed Fur side glazed Edge bite and clearance Expansin/cntractin cefficient Pint fastening materials Lading tables fr gauge, width & length and cmbinatins theref. STRENGTH: Fr glass the strength shall be cnsidered inadequate nly upn actual breakage. Glass manufacturers shall test the flexure strength accrding t ASTM C-158, and reprt it fr each type f glass prduced. SOLAR/PAR TRANSMISSION Lss f slar and PAR values in glass is anticipated t be f s little change as t nt require testing f weathered samples. COMBUSTIBILITY FLAMMABILITY TYPE I: NGMA recmmends that Flammability shall be measured and reprted in accrd with ASTM D-568 ASTM D-568 supprts a sample vertically. A flame is allwed t burn until it either extinguishes itself r burns past a gage mark (100mm) n the bar. If the sample des nt burn past the 100mm gauge mark, time and extent f burning are reprted. If it burns past the gauge mark, an average burn rate, in centimeters per minute, is reprted. FLAMMABILITY TYPE II PRIMARY Standard ASTM D NGMA recmmends that Flammability fr Type II materials shall be reprted in accrd with ASTM D Unifrm Building Cde Standard 26-7 Methd fr Determining Classificatin f Apprved Light Transmitting Plastics. This methd is based n ASTM D Standard test methd fr rate f Burning and/r extent f burning f Plastics in a Hrizntal Psitin Abar f material t be tested is supprted hrizntally at ne end. The free end is expsed t a specified gas flame fr 30 secnds. The elapsed time and burn length are measured and reprted if the specimen des nt burn mre than 100mm. An average burning is reprted fr a material if it burns past the 100mm mark frm the ignited end. Classificatin requirements per UBC Standard 26-7, Sec CC-1: Plastic Materials which have a burning extent f 1 inch (25mm) r less when tested in nminal.060-inch (1.5mm) thickness (r in the thickness intended fr use) by this test CC-2: Plastic Materials which have a burning rate f 2.5 inches per minute (64mm/min) r less when tested in Nminal.060 thickness (r in the thickness intended fr use) by this test. NGMA recmmends that materials be tested in the thickness intended fr use by this Standard. 8

10 CHEMICAL & MATERIAL COMPATIBILITY ADDITIONAL FLAMMABILITY STANDARDS NGMA recgnizes that glazing material manufactures cnduct additinal tests fr varied applicatins and may r may nt apply t applicatins in the industry. They are mentined in this standard t educate and t further define material capability and t enable cmparisn if required. Certain plastics glazing materials may be reprted in accrdance with these standards. ASTM E-84 Standard Test Methd fr Surface Burning Characteristics f Building Materials bth as t equipment and test prcedure. This prcedure is similar t UL-723, ANSI N 2.5, NFPA N 255 and UBC Tw values are reprted using this test methd: Flame Spread & Smke density NFPA Class UBC Class Flame Spread A I 0-25 B II C III ** Smke (density) Develped: all classes ASTM D Applicable t Types I & II This test measures the lss f light transmissin thrugh smke prduced frm a burning plastic. ASTM D-1929 Applicable t Types I & II This test measures bth flash ignitin and self ignitin. UL 94 Tests fr Flammability f Plastic Materials fr Parts in Devices and Appliances. MISCELLANEOUS ASTM D-696: Cefficient f Expansin f Type I and Type II materials shuld be measured and reprted using this standard. ASTM E-831: Cefficient f Expansin f Type III materials can be reprted using this standard. CHEMICAL AND MATERIAL COMPATIBILITY NGMA recmmends that each manufacturer f a prduct that cmes int cntact with glazing materials be prepared t advise the user f any ptential prblem r ther incmpatibility with a specific type f glazing material. Likewise, a glazing manufacturer shuld warn ptential custmers f any knwn prducts that are incmpatible with their glazing. These wuld be prducts that wuld be used in a greenhuse (Structure) and wuld cme int cntact with the glazing. This wuld include but nt be limited t the fllwing. Anti- fgging agents Plasticizers used in glazing system gaskets, fasteners, shade clths, thermal blankets, etc. Sealants and caulking cmpunds Wd preservatives Shading cmpunds Shading fabrics Washing cmpunds Repair tapes Pesticides, by chemical class f cmpund The carrier (slvent) fr any f the abve prducts When a grwer uses new materials he is urged t ask the manufacturer abut the cmpatibility f it with ther materials f cntact in the greenhuse. 9

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