Diffusers and grilles are the part of the HVAC system that people see, so the choice is both technical and architectural. All the types below are made of aluminium; the differences are the air pattern, the ceiling or wall they suit, and the options. This guide compares them using our product pages and datasheets.
The five main types
Square 4-way diffuser
Four-way air pattern; five frame styles and four core designs; fits 300, 375, 450 and 600 mm ceiling grids; 150 × 150 to 600 × 600 mm.
Round diffuser
360° radial air pattern; neck diameters from 150 mm to 600 mm; compatible with spiral duct connections.
Linear slot diffuser
Extruded aluminium; 1 to 4 slots; adjustable blades for horizontal 1-way, 2-way or vertical air; 600 to 2000 mm long.
Linear bar grille
Single deflection for supply and return; 1 to 4 slots; 600 to 2000 mm; double deflection and curved versions.
Grilles and registers
Single deflection controls one axis, double deflection both axes; for duct, ceiling and sidewall supply air.
For lay-in ceilings, the tile diffuser is designed for 600 × 600 mm suspended ceiling tiles, with multiple core styles. The curved linear slot diffuser is made to custom curvature and lengths for radius ceilings, and the curved bar grille comes convex or concave.
Side-by-side comparison
| Type | Typical use | Key options | Datasheet |
|---|---|---|---|
| Square 4-way diffuser | Commercial, office and institutional ceilings with a grid | Five frame styles, four core designs; equalizing grid and opposed blade damper accessories | Square diffuser page |
| Round diffuser | Uniform 360° coverage; spiral duct connections | Multiple neck sizes, 150–600 mm | Round diffuser page |
| Linear slot diffuser | Modern interiors with a continuous slot look | 1–4 slots, 16 or 20 mm slots, mitered corners, plenum boxes, curved version | Linear slot page |
| Linear bar grille | Supply and return in long, linear runs | Single or double deflection; curved (minimum radius 1000 mm); end flanges | Linear bar grille page |
| Grilles and registers | Duct, ceiling and sidewall supply air | Single or double deflection; mullions on widths over 400 mm | Grille page |
A flat ceiling grid usually points to a square or tile diffuser. A continuous architectural line points to a linear slot diffuser or a linear bar grille, and a sidewall or duct-mounted outlet to a deflection grille. On a double deflection grille, the front row of blades sets the vertical angle and the rear row sets the horizontal direction.
Supply, return and balancing
Linear bar grilles are made for both supply and return air, and the linear slot diffuser datasheet covers both supply and return construction. The square diffuser datasheet gives air-flow data for supply and return.
Flat back plenum
For direct mounting of a linear slot diffuser on a wall or solid surface, for supply air; in standard module lengths.
Round spigot top plenum
Connects a linear slot diffuser to flexible circular ducting, for exposed ceilings with round ductwork above.
Opposed blade damper
Fitted behind the diffuser neck or inside the plenum box to balance air volume during commissioning.
Finishes and air-flow data
- Standard finishes: RAL 9010 white, gloss or matt, and RAL 9005 matt black.
- Other RAL colours are available on request.
- Air-flow data: the square and round ceiling diffuser, linear slot diffuser and grille datasheets include air-flow data tables.
- Pressure drop: the round ceiling diffuser datasheet also gives pressure drop.
- Each datasheet is on its product page under Downloads.
Dusty intakes: sand-trap louvers
Fresh-air intakes in Qatar face sand and dust. A sand-trap louver separates sand and dust from the incoming air with vertical blades that make the particles drop out as the air changes velocity. It conforms to SMACNA standards and comes in custom sizes with a RAL powder-coat finish. The product page lists a maximum recommended velocity of 760 fpm, a free area of 31 % and a maximum pressure drop of 0.15 in wg.
Send your air-outlet schedule through the quote form for a formal quotation within 4 business hours, and request datasheets for the submittal through the submittal page.