Double deflection grilles 21-D Product description Double deflection grille, KOOLAIR, model 20-DH, of dimensions LxH, for supplying air with horizontal and vertical blades, individually adjustable. It can incorporate volume control damper (-O). Finished in anodised aluminium or any RAL colour upon request. Other models 20-DV. Double deflection grille, first blades in vertical position, made in aluminium. 21-DH. Double deflection grille, first blades in horizontal position, made in steel sheet. 21-DV. Double deflection grille, first blades in vertical position, made in steel sheet. Mounting With pressure clips. Mounting frame needed (-MM). Conceled fixing (-SFO). Mounting frame needed (-MM). With screws. Without indication, the grille is provided with holes for screwing the mounting frame. With plenum box made of galvanised steel sheet, side or top entry connection (-PE21/20). General dimensions Selection table The Selection Table shows a summary of dimensions. Other sizes available. Consult the Sales Department. LEGEND Q (m3/h): Air flow. Lwa [dB(A)]: Sound power level. APt (Pa): Total pressure loss. X (m): Throw for a maximum velocity of 0.25 m/s at the occupied zone AT = -10 °C (cold), installed at 2.7 m of height, with ceiling effect. Vk (m/s): Effective velocity.