• The performance data which follows permits quick, easy, and accurate selection of supply grilles and registers.
  • Two groups of data are required for selection.
  • Inherently required by the structural and room-use considerations.
  • The required performance characteristics of the supply outlets.
  • Consider first the spaces which are to be conditioned and their effects upon outlet selections. 
  1. m3/h - The air volume to be delivered to each space is determined by the number of outlets which supply each space is determined by overall system design, and the m… per outlet is determined by the number of outlets which supply each space.
  2. NC Level - The permissible sound level in each space may be specified by the owner or the architect, or it may be determined as an engineering design goal. Figure 1 contains an abbreviated list of design goals for air conditioning sound control in common occupancies.
  3. Throw Requirement - The required throw is determined from the building plan. Often the throw requirement will be the distance from the outlet to the opposite wall. Sometimes it will be the distance from the outlet to the intersection of its air system with air being delivered from another supply outlet.
  • Other items to be considered are the spread requirement, permissible drop, and acceptable pressure drop.
  • The air stream should spread sufficiently so that the wall or space at the end of the throw is blanketed.
  • The drop of the air stream should not be so great that is within 1.5m of the floor at the end of the throw.
  • Finally, the allowance in the design of the system for outlet pressure loss should not be exceeded.
  • After the design requirements – air flow, NC level, throw spread, and drop requirements – are known, the outlet can be selected.

19 mm Louvres

  • The basic selection data are given in the Tables to follow for grilles and registers having louvers on 19mm spacing. For each listed air volume, the static pressure drops and two values of throw are given for each grille area factor.
  • The minimum throw is the distance the air will travel to a terminal velocity of 0,64m/s; the maximum throw is the distance of air travel to a terminal velocity of 9,41 m/s
  • For each m3/h and the grille size, selection data are given at three spread angels 0°, 22 ½°, and 45°
  • NC level is coded in 5db increments for each m3/h, spread angle, and area factor in the table.
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