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email:: sales@scottaire.com
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Double Deflection Grilles

Grilles with a double row of individually adjustable teardrop section blades and flanged borders. Supplied with or without an opposed blade damper.


Code 0202. Horizontal front blades.
Code 0224. Vertical front blades.


Standard Specification

50mm increments in nominal sizes from 100mm to 1200mm on length or height.

Aluminium with mechanical joints to lock the mitred corners of the flange.

Silver satin anodised to BS 1615 AA5.

Countersunk screw holes in the border. Size no.
6 x 11/2´´ self tapping screws provided with each grille and painted the same colour as the grille. (Fixing type 0F1) See Fixing Methods section for screw fixing

Each grille is shrink wrapped in polythene with
additional cardboard support to the faces.

See pages 5 & 6



Optional Alternatives/Additions

Non-standard sizes. We can manufacture almost any non-incremental nominal size up to 1200mm square. Please contact Head Office for details. The product code becomes 9202 or 9224.

Opposed blade damper. A clip-on opposed blade damper in mill finish aluminium. Code 0106 if
incremental, Code 9106 if non-incremental.

Any BS, RAL or NCS colour. Code 0145. Please specify the colour reference. We suggest powder
coating on top of anodising for swimming pool applications. It may also be possible to anodise to alternative finishes for substantial quantities. Details on request.

Un-punched borders. Fixing type OF2
Concealed fix/sub frame and un-punched
borders. Fixing type OF3.


Ordering Detail

• The code for the basic grille should have 13 digits.
See page1.
• Please always give length first, then height.
• Add codes for additions / alternatives as suffixes.
A standard double deflection grille with horizontal front blades, nominal size 900mm x 500mm,
painted RAL 9010 matt, opposed blade damper, no fixing holes in the border, top entry pan adaptor
with a flange would be coded: 0202/00900/0500+0106+0328+
0145 RAL 9010 matt +0F2.
Applications. Supply** Sidewall * Ceiling *


Pan Adapters & Plenum Boxes (uninsulated)

Top entry pan adaptor without flange (120mm high). Code 0323.
Top entry pan adaptor without a flange (17mm high). Code 0338. This height of pan should only be used where the spigot diameter plus 50 is equal to or more than the smallest nominal dimension
of the pan.
Top entry pan adaptor with flange (120mm high). Code 0328.
Side entry plenum box without flange. Code 0335.
Side entry plenum box with flange. Code 0324.
Details in the Sheet Metal Work section along with codes covering insulated plenum boxes.
Pan adaptors & Plenum boxes can be fitted with quadrant dampers in the spigot for either manual (Code 0483) or cord operated
(Code 0484) control.

We can also design boxes with non-standard heights where there is a limited space in the cavity. Please contact our technical staff at Head Office.



• To size a grille handling 0.5m3/s with a 10 metre throw at 025m2/s terminal velocity and sidewall
positioned 300mm from ceiling. Correct the throw for ceiling effect, i.e. 10÷1.33 = 7.5 metres. Enter the nomogram with 0.5m3/s volume and throw 7.5 metres.
  Mark the point where the ruler crosses the pivot line. Read off NR(15) and Duct Velocity (1.5). The
appropriate pressure drop can be obtained from table 3 (2Pa). Design throws should always be corrected using tables 1,2,4 and 5 before using the nomogram.
• Table 3 shows the spread of air achieved by setting the blades at angles of 22° and 45° in relation to the throw from the grille.

Table 3 - Spread Characteristics


Table 3 should be used to determine the number of outlets required to give adequate coverage.

1. Establish the overall throw and spread required, i.e. length and width of the space to be conditioned.

2. Read from table 3 the spread obtained at the
required distance from the terminal. This will
determine the number of terminals required. Example: A room is 10.5 metres long and 6 metres wide. It is intended the air should be discharged from the short wall down the length of the room. At 10.5 metres and blades set at 22°, the spread
will be approximately 6 metres so one terminal will
provide adequate coverage.

3. However, the nomogram on page 5 is based on straight blades. Setting the blades at 22° or 45° will reduce the effective throw of the grille for any given airspeed through it. So it is necessary to apply a
correction factor to the design throw before using the nomogram in order to compensate for this reduction. Table 4 shows the correction factor which should be used as a multiplier to the design throw. The corrected throw can be used in the nomogram.

Table 4 - Correction to throw for Blade Angle and Ceiling Effect


Example: The throw required is 10.5 metres. The blades are to be set at 22°. The grille is more than 500mm from the ceiling. Multiply 10.5 by 1.5.
This gives a corrected throw of 15.75 metres which should be used in the nomogram.

4. The other factor to be considered in selecting grilles is the heating and cooling of the primary air. Cooled air will tend to fall and this, in particular, should be considered when selecting grilles and diffusers. The amount of drop in the airstream can be determined from Table 5.

Table 5 - Drop Date





  SCOTTAIRE Davy Way, Llay Industrial Estate, Wrexham,LL12 0PG Tel: 01978 856555 Fax: 01978 856655 Email: sales@scottaire.com