????? ??? ??????? ??????? ??? ???? ???? ???? ??? ????? ?????? DUCT WORKS Selection Tips DETAILED TECHNICAL SPECIFICATION Joints Turning VanesVolume Control DamperFire DampersGrilles and Registers They must be furnished with sponge rubber gaskets or foam tape behind the frame to eliminate air leakage and with nylon bushings or PVC at the blades connection to the frame to eliminate corrosion and vibration. Free cross-sectional area must be at least 65 percent 1- Supply air registers and grilles must have individually adjustable horizontal front blades and vertical rear blades 2- Supply air register must be equipped with key operated, opposed blade volume control damper 3- Return and exhaust air registers and grilles must have fixed single deflection blades set at an angle of 35 degrees 4- Return and exhaust air registers must be equipped with key operated, opposed blade volume control damper 5- All opposed blade volume control dampers must be polyester powder coated ovens taken with black colour finish Jet Diffusers must have manual discharge pattern adjustment from the front or back of diffuser, the outer flange of the jet diffuser to be made of aluminium, the inner core and rings to be made of mild steel construction, to be coloured by electrostatic polyester powder coating finish Access DoorsFlexible Connections Flexible connections must be fitted on all suction and discharge connections of fans and air conditioning units, for preventing transmission of vibration through the ducts to occupied spaces Flexible connections must be made from flame proof, factory fabricated from chemically impregnated canvas Connections must fit closely and be secured in an airtight fashion to duct work, fans and apparatus by means of angle iron or flat iron frames. The unclamped section of the flexible connection between the apparatus and the ductwork must be not less than 150 mm. in length. Flexible connections must not be painted Supports and Hangers
