Measuring Gas Velocity with the D-FL 100 Differential Pressure Bar

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D-FL 100IllustrationsFig. 1: Diagram of a Pitot tube .......................................................................................................2Fig. 2: Diagram of a differential pressure bar inside a stack......................................................3Fig. 3: Dividing the duct/stack cross section into equal ring surfaces .....................................4Fig. 4: Possible settings of the switching valve...........................................................................5Fig. 5: Overview of the system components ................................................................................6Fig. 6: Cross section of the differential pressure bar..................................................................7Fig. 7: Diagram of a differential pressure transducer..................................................................8Fig. 8: Front cover of D-FL 100-10 Display .................................................................................10Fig. 9: Installation positions of the differential pressure bar ...................................................12Fig. 10: Installation of the differential pressure bar I (Dimensions in mm)...............................12Fig. 11: Installation of the differential pressure bar II (Dimensions in mm)..............................13Fig. 12: Connection of the pressure pipes ...................................................................................13Fig. 13: Electrical connection of the transducer ..........................................................................14Fig. 14: Connection diagram of socket rack 1 (19-inch rack mount system) ...........................15Fig. 15: Connection diagram of socket rack 2 (19-inch rack mount system) ...........................16Fig. 16: Dimensions of D-FL 100-10 (19-inch rack mount system) ............................................17Fig. 17: Connection diagram of terminal strip (housing model) ................................................18Fig. 18: Dimensions of D-FL 100-G (fieldhousing for 19-inch rack)...........................................19Fig. 19: Turning knob ......................................................................................................................21Fig. 20: Probe cross sections ........................................................................................................27Fig. 21: Drawings of the mounting flanges...................................................................................28Fig. 22: Overview of parts...............................................................................................................32Abb. 23: Gerätevarianten, Darstellung außerhalb Kamin .............................................................35Abb. 24: Gerätevarianten, Darstellung im Kamin ..........................................................................36Abb. 25: Anschlussplatte, für Differenzdruck-Messumformer.....................................................37GmbH
D−FL 100 Seite 11. ApplicationOne of the most popular and reliable methods of measuring the differential pressure in a duct or stack isby means of a mechanical device such as a venturi or a differential pressure bar.The differential pressure bar is useful in measuring the velocity of exhaust gases that are not saturatedwith steam or water vapors. These gases may be generated by burning fossil fuels; e.g., in currentplants, waste incinerators and cement kilns. The differential pressure bar is designed to measurebetween 0 and 2,000,000 m 3 /h, depending on velocity and on the inner diameter of the duct/stack. Theminumum velocity should be more than 3 m/s.The DURAG D-FL 100 Velocity Measuring System has been suitability tested by TÜV Nord, Test ReportNo 128CU11650 dated 29. March 1996.2. Functional DescriptionThere are several advantages to using a differential pressure bar instead of a venturi to measure thevelocity of a gas. A venturi reduces the pressure, thus causing pressure loss, whereas a differentialpressure bar has only a marginal influence on the gas flow. Because a differential pressure bar hasminimal effect on the gas flow, it can be used in shorter ducts/stacks, where installation of a venturiwould not be as cost-effective. Finally, a differential pressure bar requires less blower force for equalgas velocity, making it less expensive in overall operating costs.The velocity of a gas in a duct/stack is derived from the difference between the total impact pressureand the reference pressure on the differential pressure bar or Pitot tube (Fig. 1). This relationship isexpressed by Bernoulli’s equation:(Eq. 1)ΔPPgesPstatρvdifferential pressuretotal impact pressure (flow side)static (reference) pressuregas densityvelocityGmbH
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Page 6 and 7: D−FL 100 Seite 2Fig. 1:Diagram of
Page 8 and 9: D−FL 100 Seite 4placed on the dif
Page 10 and 11: D−FL 100 Seite 63. System Compone
Page 12 and 13: D−FL 100 Seite 83.2. Differential
Page 14 and 15: D−FL 100 Seite 10LED DisplayStand
Page 16 and 17: D−FL 100 Seite 12After the differ
Page 18 and 19: D−FL 100 Seite 144.3. Electrical
Page 20 and 21: D−FL 100 Seite 16Fig. 15:Connecti
Page 22 and 23: D−FL 100 Seite 18Fig. 17:Connecti
Page 24 and 25: D−FL 100 Seite 205. Start-Up / Er
Page 26 and 27: D−FL 100 Seite 22LED readout inst
Page 28 and 29: D−FL 100 Seite 247. MaintenanceTh
Page 30 and 31: D−FL 100 Seite 26Differential Pre
Page 32 and 33: D−FL 100 Seite 28Installation fla
Page 34 and 35: D−FL 100 Seite 30Inner diameter(m
Page 36 and 37: D−FL 100 Seite 329.5. Ordering In
Page 38 and 39: D−FL 100 Seite 34** Other materia
Page 40 and 41: D−FL 100 Seite 369.6.2. Variant e
Page 42 and 43: D−FL 100 Seite 3810. Calculation
Page 44 and 45: D−FL 100 Seite 4010.1. Explanatio
Page 46 and 47: D−FL 100 Seite 420C ° = b · 4mA
Page 48 and 49: D−FL 100 Seite 44GmbH
Page 50 and 51: D−FL 100 Seite 46II.Eignung von M
Page 52 and 53: D−FL 100 Seite 48DURAG GROUP comp

Measuring Gas Velocity with the D-FL 100 Differential Pressure Bar

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