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Glossary Of Terms / C-D

Glossary Of Terms / C-D Contraflam A fire safety glass sealed glass unit containing clear heat absorbing gel used in fire rated installations. Countersunk hole A hole which has been ground out at the surface to receive a mechanical fixing and bush, allowing the bolting or fixing of the glass panel. The head of the bolt will be flush with the surface of the glass. Convection Heat transfer in where actual movement of the medium, gas or liquid occurs. Crash rail A rail, together with its fixings, capable of withstanding a load of 750N per metre length, acting in any direction without contact with the glazing material. Cullet Waste glass that can be recycled and fed into a glass making furnace. Cure time The time necessary for the mixed compound to develop to a state that can be handled in production and moved without distorting the sealant. The longer the work life, the longer the cure time. Decibel A measure of noise loudness. Deflection The amount of bending or flexing of the centre of a glass panel at right angles to the plane of the glass surface under load. Delamination A condition in which one or more of the glass plies of laminated glass loses the bond with the interlayer. Density How heavy glass is. Glass weighs 2.5 grammes per cubic centimetre. One square metre of 4mm thick glass weighs 10 kilos. Desiccant Substance used to adsorb moisture inside the air space of secondary glazing or an IGU. Desiccant adsorbs moisture that has become trapped in an insulated glass unit during manufacture as well as moisture that diffuses through the edge seal throughout the life span of the unit. Design wind pressure The specified wind pressure a product is designed to withstand. 228 Product Catalogue For Glass Processors & IG Manufacturers

Glossary Of Terms / D Dew/frost point The temperature at which condensation begins when air is cooled. One of the most common indicators of insulated glass performance. Diamant Trade name for a low iron extra clear glass. Diffuse To spread light rays in all directions. This lets light pass but makes it softer. Diminishing stop bevel A bevel in which only a portion of the surface edge is bevelled. The bevel running out on a small radius. Direct transmittance The portion of solar heat energy which is directly transmitted through the glazing. Distance piece Small blocks of resilient, non-absorbent material (such as extruded rubber) used to hold in place the glazing compound or sealant. They are positioned opposite each other between the glass and rebate, and glass and bead. Refer to Shims. Distortion Alteration of viewed images caused by variations in glass flatness. It is an inherent characteristic of glass that has been heat treated. Double glazing Two panes of glass separated by an air space. This improves insulation against heat transfer and/or sound transfer. Normally a referred to an Insulating Glass Unit. Refer to IGU. Draw lines Refers to the direction of flow (or pull) of the glass during production of sheet glass. Float glass has eliminated this issue. Dry glazing Glazing, or sealing in, of single glass or IGU in the supporting framing system without wet sealants using pre-formed and extruded materials such as glazing gaskets. Also called compression glazing. Dry seal A weather seal between the glass and frame using foam tapes or gasket materials. Note: A dry seal may not be completely watertight. Dual seal Double glazed units comprising a primary seal (PIB) and a secondary seal using either Polysulphide, Hotmelt, Polyurethane, or Silicone for maximum protection against moisture vapour transmission. Durometer An instrument for measuring Shore Hardness of materials such as rubber. Email: info@fgtrading.co.za | Web: www.fgtrading.co.za 229