Constant flow damper

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Rafe Morgan
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Constant flow damper DAU Dimensions B Ød l Description Constant flow damper with manual setting of one flow DAU is a constant flow damper, which facilitates balancing of entilation systems and gies

1 Constant flow damper DAU Dimensions B Ød l Description Constant flow damper with manual setting of one flow DAU is a constant flow damper, which facilitates balancing of entilation systems and gies correct flow from the start. The unit compensates for e.g. connection and disconnection of system parts, clogging of filters and ducts, thermal lift forces, wind effects, window opening etc. A special mounting, measuring, balancing and maintenance instruction exists for this product. Flow setting The flow is set by loosing the central nut and ia the knob turning the scale arrow so it points at the wanted flow on the scale. Then the locking nut is tightened. Ød nom l mm B mm Weight kg Tightness class across closed blade 0, 0,0 0, 0 0 0, 0, 0 0 0, 0 Center nut Scale arrow Ordering example Product Dimension Ød DAU We resere the right to make changes without prior notice

2 ariable flow damper Summary DAU - manual single flow unit DAEU - motorized twin flow unit DAVU - motorized ariable flow unit Diameters Ø 0 Flow range 0 l/s ( m³/h) Pressure range Pa (oer the unit) Independent of mounting direction Handles mm duct insulation Aailable preinsulated Function The constant flow damper is an automatic damper, which at arying 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 torue. This is balanced by an opposed opening force from a spring. The greater the pressure across the blade the more it closes. A bellow eliminates oscillations, which could occur at unfaourable conditions of operation. Types The following types exists: DAU one flow unit with knob and arrow for manual setting of one flow. DAEU two flows unit with electric motor for switching between two flows. DAVU ariable flow unit with electric motor for continuous setting of one flow. Material Housing and damper blade are of galanized sheet metal and shaft is of stainless steel. Temperature Working range: + to +0 C. Insulation The units can handle mm duct insulation without the scale or the motor being hidden. The units can be ordered with an external insulation and an outer sheet metal shell for lower sound radiation to the surroundings. Regulating accuracy The units are calibrated from factory within their whole working range. In this the units keep the flow constant within approximately ± to ±% of the set flow. Greater deiations occur at the lower flows, aspecially for small sizes. DAU, DAEU, DAVU Flow settings The units can not be deliered from factory with a preset flow. You can set the flow yourself ery easy following to the instruction for each product. Disturbance tolerance In order to achiee the stated accuracy for the pre-set flow a straight distance of at least d before and at least, d after the units are reuired. A mounting close to a source of disturbance (bend, saddle etc.) decreases the regulation accuracy and the flow may deerge from the set alue. Change of direction The units are independent of their mounting direction and one may deiate 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 0. Constant flow damper combined with shut off damper can with adantage 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 Forced flow = 0 l/s = l/s = l/s Four flows will then be posssible: 0, 0, 0 and 0 l/s. Basic flow Forced flow Forced flow We resere the right to make changes without prior notice

3 ariable flow damper Pressure and flow ranges and sound to duct The graphs show A-weighted sound power leel,, to duct. These curs are intended for brief comparision. For more accurate calculation, please use the tables. Example Gien: Diameter mm Flow 0 l/s Pressure drop Pa The graph gies: A-weighted sound power leel approx. db The table gies: Sound power leel as below Centre freuency [Hz] 0 k k k k Sound power leel DAU, DAEU, DAVU Ø [l/s] Ø [l/s] Ø [l/s] We resere the right to make changes without prior notice

4 ariable flow damper DAU, DAEU, DAVU Pressure and flow ranges and sound to duct Ø 0 0 Ø [l/s] 0 [l/s] 0 0 Ø [l/s] We resere the right to make changes without prior notice

5 ariable flow damper DAU, DAEU, DAVU Sound to duct Sound power leel, L W, to duct in octae bands, 0 Hz, as function of diameter, pressure drop and flow. Ød Pressure drop Velocity app., Velocity app. Centre freuency [Hz] Centre freuency [Hz] 0 k k k k 0 k k k k Flow [l/s] Flow 0 [l/s] Flow 0 [l/s] Flow [l/s] Flow 0 [l/s] Flow 0 [l/s] Flow 0 [l/s] 0 Flow 0 [l/s] Flow 0 [l/s] Flow 0 [l/s] Flow [l/s] Flow [l/s] We resere the right to make changes without prior notice

6 ariable flow damper DAU, DAEU, DAVU Sound to duct Sound power leel, L W, to duct in octae bands, 0 Hz, as function of diameter, pressure drop and flow. Ød Pressure drop Velocity app. Velocity app. Centre freuency [Hz] Centre freuency [Hz] 0 k k k k 0 k k k k Flow [l/s] Flow 0 [l/s] Flow 0 [l/s] Flow [l/s] Flow [l/s] Flow 0 [l/s] Flow [l/s] Flow 0 [l/s] Flow 0 [l/s] Flow 0 [l/s] Flow [l/s] Flow [l/s] 0 We resere the right to make changes without prior notice

7 ariable flow damper Pressure and flow ranges and sound to the surroundings The graphs show A-weighted sound power leel,, to the surroundings. Example: Gien: Diameter mm Flow 0 l/s Pressure drop Pa The graph gies: A-weighted sound power leel approx. 0 db The A-weighted sound pressure leel in the mittle of the room becomes approx. db lower than these graph alues. With insulation shell around the unit the sound pressure leel in the mittle of the room becomes appox. db lower than the graph alues on condition that also the connected ducts are attenuated (insulated) to the same extent. Still lower sound pressure leel can be achieed with additional constructional sound attension measures (false ceiling, high room attenuation). Ø 0 0 DAU, DAEU, DAVU Ø 0 Ø [l/s] [l/s] [l/s] 0 We resere the right to make changes without prior notice

8 ariable flow damper DAU, DAEU, DAVU Pressure and flow ranges and sound to the surroundings Ø 0 0 Ø [l/s] [l/s] 0 0 Ø [l/s] We resere the right to make changes without prior notice

Constant-/variable flow damper

Constant-/variable flow damper lindab constant -/ariable flow dampers Constant-/ariable flow damper DAU Dimensions B Ød l Description Constant flow damper with manual setting of one flow DAU is a constant flow damper, which facilitates