An insulated glass (IG) sealed unit is made with two panes of glass which are separated with a spacer frame made from tube or foam spacer (tube can be bent or cut and corner keyed). The spacer frame is fixed onto the two panes of glass with a primary sealant.
A spacer tube is filled with desiccant on two sides of the frame (foam spacer is manufactured with a desiccant compound included and then a secondary sealant is applied to the back of the spacer to seal the unit.Insulated glass sealed units can also be gas filled to improve their thermal efficiency. It is generally accepted that a high performance unit which achieves a higher Window Energy Rating is put together similar to double glazed sealed unit - one low-e glass pane and the other glass pane float or low-iron. You then have various options in terms of gas-filling, warm edge spacer, desiccant and sealant. Whether you apply single or dual seal, it's the care you take over the construction and the choices of the components that you make that will help to guarantee the longevity of your sealed unit.

Glass Preparation
  • The two panes of glass that will be used to make the sealed unit are measured and cut to size by hand. Alternatively, an automatic cutting table can be used which reduces waste and manpower. Glass can also be ordered from suppliers in large sheets cut to size, or they can be made to order.
  • BASSRA supplies machines for removing the low-e perimeter (soft coat) surface coating from the edge of a glass panel prior to its use in an insulated glass sealed unit. Edge deletion is necessary because the low-e coating on the glass surface affects adhesion with insulated glass sealants. Removal of the edge coating means that the sealant can bond directly to the glass. Please confirm this requirement with your glass supplier.
  • Glass panes are then fed through a glass washer/dryer using demineralised water. After being washed they are thoroughly inspected by the operator. For leaded units, the leading is applied to the glass which is then fed through the washer a second time. We supply a range of glass washers, both horizontal and vertical, as well as water purification units/treatment plants (essential for soft coat), demineralising units and the resin.
  • If bevels have been applied to the glass they are now 'cured' using a UV lamp or bench (these can be supplied by BASSRA). BASSRA supplies a range of bevels, lead and colour film, as well as a range of tools and accessories for applying these to the glass.

Spacer Frame Construction
  • Tubular Spacer bar - can either be bent or cut and used with corner keys to construct a frame to be used to create airspace between the two panes of glass in a double glazing sealed unit. The width of the spacer bar determines the cavity depth within the sealed unit.
  • Spacer Bar Bending - A length of spacer is cut to size and bent in 4/3 corners to create a rectangular frame (spacer tubes can also be curved for unusual shaped glass sealed units). The two ends of bar are then joined either using one corner key for a corner joint (for gas filling this must be a corner key with a hole), or with a straight connector for a join along the length of the spacer tube. BASSRA supplies a range of spacer bar bending machines as well as the accessories they require. Please note that some spacer tubes are more suitable for bending than others.
  • Spacer Bar Cut and Corner Keys - Four lengths of spacer are cut to the correct length (standard size is 24mm shorter than the glass size) and then joined together with compatible corner keys to create a rectangular framework. bending machines and saws. A wide range of Georgian Bar and accessories is also available, as well as Aluminium and UPVC Surface Mount Georgian Bar.

  • Desiccant Filling
  • Desiccant Filling - The completed spacer frame is filled with desiccant which adsorbs any moisture that may trapped in-between the two panes of glass during manufacture, or which finds a way into the sealed unit throughout the lifetime of the unit. It is standard practice in cut and corner key units that two of the four spacer tubes are filled with desiccant. BASSRA supplies a range of desiccants and also manual and automatic desiccant dispensers to fill spacer tubes. It is important that you purchase a pure 3A desiccant to ensure the longevity of your sealed units. Ask about our desiccant testing service and test kits we can supply. Primary Seal
  • Polysulphide or PIB is applied to both edges of the spacer tube framework. This is then carefully pressed in place in-between the two panes of glass. PIB can be hand applied, but is usually applied using a PIB machine. BASSRA supplies PIB and a range of PIB machines suitable for small and large IG manufacturers.
  • Secondary Seal
    There are various options of secondary sealant which can be applied to the outer edge of IG units to provide a dual seal.

  • various options of secondary sealant which can be applied to the outer edge of IG units to provide a dual seal. •Hot Melt / Hotmelt (most popular secondary sealant used in the UK market) - one component sealant applied at 170-190°C has no curing time. Simply wait to cool down and glaze.
  • Polysulphide (PS) 2-component chemically curing sealant.
  • Polyurethane (PU) 2-component chemically curing sealant.
  • Silicone one or two part chemically curing sealant.
Various ranges of all of the above sealants are supplied by BASSRA , as well as a variety of machines suitable for applying each sealant including: Hot Melt Extruders and replacement guns; Glass Sealing Tables; PS and PU Mixing and Silicone Dispensing Pumps; and digital thermometers(for checking the application temperature of your sealant).

Gas Filling

Gas filling is a means of improving the thermal efficiency of your IG unit to produce a high performance glass sealed unit. In fact, if you gas-fill your units, it is possible to achieve a 'C' grading under the UK Window Energy Rating Scheme (WER) with some window profiles using traditional aluminum spacer bar. BASSRA supplies a range of gas fillers for filling Argon (Ar), Krypton (Kr) and Xenon gas (Xe). There is a fast-fill feature available. In addition, gas hole drilling and gas testing equipment is available. The sealed unit is then constructed with the primary seal and positioned vertically - either with one of the drilled holes positioned vertically above the other, or with both holes at the top.

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