lindab | dampers and measure units Constant-/ DAU, DA2EU, DAVU variable flow damper Summary • DAU - manual single flow unit • DA2EU - motorized twin flow unit • DAVU - motorized variable flow unit • Diameters Ø 80–315 • Flow range 15–830 l/s (54–2988 m³/h) • Pressure range 50–1000 Pa (over the unit) • Independent of mounting direction • Handles 50 mm duct insulation Function The constant flow damper is an automatic damper, which at varying pressures wholly mechanical and independent of external energy sources maintains a set flow constant. The force, needed for regulation, is taken from the passing air stream. The air stream across the blade attempts to close it and generates a closing torque. This is balanced by an opposed opening force from a spring. The greater the pres- sure across the blade the more it closes. A bellow eliminates oscillations, which could occur at unfavourable conditions of operation. Types The following types exists: • DAU – one flow unit – with knob and arrow for manual set- ting of one flow. • DA2EU – two flows unit – with electric motor for switching between two flows. • DAVU – variable flow unit – with electric motor for continu- ous setting of one flow. Material Housing and damper blade are of galvanized sheet metal and shaft is of stainless steel. Temperature Working range: +5 to +70 °C. Insulation The units can handle 50 mm duct insulation without the scale or the motor being hidden. DAU is available with an 45 mm external insulation and an outer sheet metal shell for lower sound radiation to the sur- roundings. Is then called DALU. Regulating accuracy The units are calibrated from factory within their whole working range. In this the units keep the flow constant within approximately ±5 to ±10% of the set flow. Greater devia- tions occur at the lower flows, aspecially for small sizes. Flow setting The units can not be delivered from factory with a preset flow. You can set the flow yourself very easy following to the instruction for each product. Disturbance tolerance In order to achieve the stated accuracy for the pre-set flow a straight distance of at least 3×d before and at least 1,5×d after the units are required. A mounting close to a source of disturbance (bend, saddle etc.) decreases the regulation accuracy and the flow may deverge from the set value. Change of direction The units are independent of their mounting direction and one may deviate from the specified direction and mount them in any direction without affecting the accuracy. Combinations The units can be mounted together with e.g. a motorized shut off damper DTBU, see page . Constant flow damper combined with shut off damper can with advantage be used in groups at installations where you want: • two flows, that lies too far away from each other for a two flow unit to handle or • more than two flows Presume: Basic flow Forced flow 1 Forced flow 2 = 80 l/s = 100 l/s = 150 l/s Four flows will then be posssible: 80, 180, 230 and 330 l/s. Basic flow Forced flow 1 Forced flow 2 2 DUCT-MC Identification number 17.11.002 Lindab reserves the right to make changes without prior notice
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