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

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D−FL 100 Seite 4010.1. Explanation of the calculation sheet D-FL 100Page 1First entry box: „Parameters of the gas channel“In this box the main data of the application is requested. In the first three lines only oneparameter has to be known: either the standard flow [Nm³/h] or the flow under workingconditions [m³/h] or the velocity [m/s].The inner diameter D and the flange length are used for the construction of the differentialpressure bar. The parameter n states the number of ring zones. In the flow probe 2*nmeasuring points are used. The probe number indicates the type of flow probe: Type 1 is usedfor a duct up to 2 m diameter, flow probe 2 is used for diameters between 2 and 4 m and flowprobe 3 is used for diameters between 4 and 8 m. If the dust-concentration is higher than 30mg/Nm³ flow probe 1 is not used. In that case flow probe 2 replaces the type 1.The parameters temperature t, absolute pressure P (static pressure inside the stack), thestandard density ρ n are used to calculate the range of the differential pressure transmitter.Second box: „Results of calculation“In this box the correspondent values for the standard flow, the flow under working conditionsand the velocity are calculated. Additionally the density under working conditions and thedifferential pressure are calculated.Third box: „The following transmitters are recommended“The span of the differential pressure transmitter normally is programmed a little bit greater thanthe calculated differential pressure from the data of the application (standard dP / 0.81; this isequal to 90% of the flow range). The advantage is that the transmitter has not to berecalibrated if the flow is a little bit greater than the data given from the application.The span of the absolute pressure transmitter is by default 900-1100 hPa.The span of the temperature measurement is based on the data given from the customer.Fourth box: „Calculation formula (standard flow)“This formula is based on the equation 5 (V n ) in the manual:VThis can be rearanged like:Vn2ΔP T + 273,15 Pn= A· k · ··ρ T+27315 , PΠ 273.15 3600 · 100= · 2 · ·4 1013 1000n 2n2D · k P· ·ρ T + 273,15nn·ΔPwhereby: T n 0°C D inner diameterP n 1013 hPa ρn standard density at 0°C3600 seconds per hour 100 100Pa per mbar or hPa1000 mm per mGmbH
D−FL 100 Seite 41If we want to put all the constants together the formula looks like (formula in calculation sheet):The constant Kx is calculated according:V = PKx · · Δ PnT + 273,1522Π 273.15 3600 · 100 D · k 0,020763 · D · kKx = · 2 · ·· =24 1013 1000 ρρnnHow to use this formula in a data logger (DMS 285/ DMS500 or similar)For the use of the formula always the dimensions stated below on the calculation sheet haveto be taken into account.If the transmitters are delivered from DURAG, the differential transmitter is programmed with asquare rooted output signal (4-20 mA). The temperature and the absolute pressure transmitterare programmed with a linear output signal (4-20 mA). For the evaluation formula stated on thecalculation sheet this means, that the programmer has to take care that the differentialpressure is not square rooted twice.Example :For the DMS 500 the linear input equation is:y = b · x+cwhereby x mA Signaly the physical value thatcorresponds to the mA inputFor the differential pressure transmitter with a span of 4.2 hPa / square rooted this means:42hPa . = b · 20mA + c0hPa = b · 4mA + cThe coeffizients b and c can be resolved out of this two equations: b=0.12808 c=-0.5123y = 0.1280 · x - 0.5123dpThe calculated y out of the equation replaces the square root of the differential pressure in theformula of the standard flow.For the temperature transmitter with a span of 400°C this means:400° C = b · 20mA + cGmbH
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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 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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