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Glass knowledge

  • Author:fanyumaoyi
  • Source:chinamirrormanufacturer.com
  • Release on :2016-11-28

1. What is visible light transmittance?
  
  In the visible spectrum (380 nm to 780 nm) range, the percentage of light through the glass.
  
  2. What are visible light reflectance?
  
  In the visible spectrum (380 nm to 780 nm) range, the percentage of light reflection in the glass.
  
  3. What is the solar transmittance?
  
  In the solar spectrum (300 nm to 2500 nm) range, UV, visible and near-infrared light energy through the glass of the percentage.
  
  4. What is a solar reflectivity?
  
  In the solar spectrum (300 nm to 2500 nm) range, UV, visible light, and the percentage of reflection in the glass of near-infrared light energy.
  
  5. What is the u-value?
  
  ASHRAE standard conditions, due to the glass and heat transfer temperature difference between indoor and outdoor, formed by air to air heat. English units: British thermal units per hour per Fahrenheit per square foot. Metric units: Watt per square meter per Kelvin. The lower the u-value, lower the amount of heat through the glass.
  
  6. What is the winter conditions for u-value?
  
  Outdoor air temperature of 0 degrees Fahrenheit (-18 Celsius), the indoor air temperature of 70 degrees f (21 c) and outdoor air flow rate of 15mph (24km/h), indoor air natural convection, sunlight for 0BTU/h-ft2 (OW/m2) (night).
  
  7. What is the condition of u-value in the summer?
  
  Outdoor air temperature of 90 degrees f (-18 c), indoor air temperature of 70 degrees f (21 c) and outdoor air flow rate of 7.5mph (12km/h), indoor air natural convection, sunlight for 248BTU/h-ft2 (OW/m2) (day).
  
  8. What is the shading coefficient?
  
  Under the same conditions, solar radiation through Windows of heat through heat ratio of 3mm transparent glass. Shading coefficient is smaller, the blocking of direct sun radiation the better the performance.
  
  9. What are the relative heat gain?
  
  Solar energy total heat through the glass window of the moment. Including the heat of sun radiation (shading coefficient) heating and conduction (U value). Relative increased hot more low, performance more good, by ASHRAE standard, in summer day, sun radiation strength for 200BTU/h-ft2 (630W/m2), no shade of Outdoor Indoor temperature for 14 f, is relative increased hot = summer u value x room both inside and outside temperature + shade coefficient x sun radiation strength, that relative increased hot =14x summer u value +200X shade coefficient [BTU/h-ft2] or, relative increased hot =8X summer u value +630x shade coefficient [W/m2].
  
  10. What is thermal stress cracking?
  
  Thermal stress cracking of production from different parts of the glass temperature is uneven.Coated glassExposed in Sun straight as Xia, main absorption Sun of infrared light and part visible, in glass ontology within into for energy, makes glass ontology formed hot expansion; and in aluminum box structure internal of glass part is cannot by same of sun radiation, so led to glass overall heated not uniform, internal hot stress formed, glass Central of hot expansion makes glass border region produced tensile stress, this Zhang stress over border region tensile strength, on will led to glass rupture. Glass due to thermal stress and cracking phenomenon is RIP neatly on the edge of the glass, and at right angles to the edge, crack less glass Central rift as curved rather than straight lines.
  
  11. several aspects of the effects of thermal stress is what?
  
  Building orientation, cold weather condition, size, and shape, heating facilities, window systems, indoor and outdoor covered, glass body absorption.
  
  12. What is heat-reflective glass?
  
  Heat-reflective coated glass of glass is called, it is on the surface of the glass coated with metal film and metal oxide or nitride films, glass shading coefficient of Sc from 0.98 (6mm clear glass) down to 0.2~0.6 form.