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
Page 1 and 2: 11/07Measuring Gas Velocitywith the
Page 3: D-FL 100Table of Contents1. Applica
Page 7 and 8: D−FL 100 Seite 3The output signal
Page 9 and 10: D−FL 100 Seite 5To prevent residu
Page 11 and 12: D−FL 100 Seite 73.1. Differential
Page 13 and 14: D−FL 100 Seite 9If the differenti
Page 15 and 16: D−FL 100 Seite 114. Installation4
Page 17 and 18: D−FL 100 Seite 13Fig. 11:Installa
Page 19 and 20: D−FL 100 Seite 15Fig. 14:Connecti
Page 21 and 22: D−FL 100 Seite 17Fig. 16:Dimensio
Page 23 and 24: D−FL 100 Seite 19250 mm13538,5 18
Page 25 and 26: D−FL 100 Seite 215.2. Start-up of
Page 27 and 28: D−FL 100 Seite 235.3. Error Messa
Page 29 and 30: D−FL 100 Seite 258. Specification
Page 31 and 32: D−FL 100 Seite 27Fig. 20:Probe cr
Page 33 and 34: D−FL 100 Seite 299. Selecting the
Page 35 and 36: D−FL 100 Seite 319.3. Selecting t
Page 37 and 38: D−FL 100 Seite 33DescriptionHose
Page 39 and 40: D−FL 100 Seite 359.6. Illustratio
Page 41 and 42: D−FL 100 Seite 379.6.3. Mounting,
Page 43 and 44: D−FL 100 Seite 39Customer: XYZ da
Page 45 and 46: D−FL 100 Seite 41If we want to pu
Page 47 and 48: D−FL 100 Seite 4311. Measuring Po
Page 49 and 50: D−FL 100 Seite 45GEMEINSAMESMINIS
Page 51 and 52: D−FL 100 Seite 47EG-Konformitäts
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Measuring Gas Velocity with the D-FL 100 Differential Pressure Bar

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