CEBU INSTITUTE OF TECHNOLOGY
                          N. Bacalso Avenue, Cebu City
                      Chemical Enginee...
Abstract:

        Controlling the flow in piping systems is a significant issue in the chemical
process industries. Obvio...
Objectives:

       1.) To plot the coefficient of discharge of a sharp – orifice versus Reynold’s number
       2.) To pl...
maintaining a small but constant overflow. Flow from the orifice was derived by measuring
    the time taken to fill the m...
Orifice:                              Co = 2.119
Trial 1:                                                                 ...
Fig.1.2 shows the diagram of Re vs. Co for Venturi

Data Analysis :

       Based on the graph plotted above, the calibrat...
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Calibration of Orifice & Venturi Meter

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ChE Laboratory Exp't, Calibration of Orifice & Venturi Meter - Final Report

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Calibration of Orifice & Venturi Meter

  1. 1. CEBU INSTITUTE OF TECHNOLOGY N. Bacalso Avenue, Cebu City Chemical Engineeing Department FINAL REPORT ChE Lab 1 Title of Experiment Juphil A. Lamanilao BSChE-5 Engr. Lyda P. Abellanosa Instructor
  2. 2. Abstract: Controlling the flow in piping systems is a significant issue in the chemical process industries. Obviously, in order to control the flow in a pipe, the flow must be measured. This experiment will introduce you to two devices that are used to measure flow. One, the venturi meter, is a device used for measuring the rate of flow of a fluid through a pipe. Water is allowed to flow through the meter at different rates ranging from zero to the maximum and the corresponding pressure differences shown in the manometer are noted. The actual discharge is determined using the measuring tank and the stop watch. The second, the orifice meter, is a device used for measuring the rate of flow of a fluid through a pipe. It works on the same principle as a venturi meter. It consists of a flat circular plate which has a circular sharp edged hole called orifice, which is concentric with the pipe. The orifice diameter is 0.5 times the diameter of the pipe. A differential manometer is connected at section 1 which is at a distance of about 1.5 to 2 times the pipe diameter upstream from the orifice plate, and at section 2, which is at a distance of about half the diameter of the orifice on the downstream side from the orifice plate. It can be set up to be read locally or remotely using pressure transducers. Both are designed for flows that do not contain significant amounts of solid material.
  3. 3. Objectives: 1.) To plot the coefficient of discharge of a sharp – orifice versus Reynold’s number 2.) To plot the coefficient of discharge of a venture versus Reynold’s number. 3.) To obtain data on pressure drop versus water flow rate. Materials & Equipment: Hydraulic bench apparatus, orifice meter, venture meter, graduated cylinder, stopwatch, manometer, water, ruler Sketch of the Set-up: Procedure: A. The inlet head tank was positioned on the mounting studs provided on the bench working surface so that the orifice set discharges into the weir channel. The inlet hose was attached from the bench regulating valve to the inlet of P6103. From here, the overflow pipe was connected to the overflow of the bench measuring tank. The orifice is screwed under test into the side outlet position or the base outlet as required. Required heads were obtained by
  4. 4. maintaining a small but constant overflow. Flow from the orifice was derived by measuring the time taken to fill the measuring tank between predetermined levels. Readings were taken from the provided manometer at a convenient time interval. B. The procedure above was repeated using venture meter instead of orifice. Tabulated Data & Result: Orifice: Manometer Reading (mm) Volumeteric TRIAL Rm Co NRE Upstream Downstream Flow Rate 1 43 2 41 313.03 2.119 31204.66 2 47.7 2.5 45.2 345.63 2.228 34454.422 3 50.7 4.1 46.6 346.15 2.198 34506.263 4 52.6 7.3 45.3 346.57 2.232 34548.13 5 64 14.5 49.5 347.46 2.1405 34636.85 6 69.5 18.5 51 349.77 2.123 34867.12 7 74.5 21.5 53 350 2.084 34890.05 8 82 25.5 56.5 352.38 2.032 35127.302 9 88.5 3. 58.5 369.81 2.096 36864.83 10 97 31.75 65.25 381.46 2.047 38026.17 TRIAL Manometer Reading (mm) Volumeteri Rm Co NRE Upstream Throat Downstream c Flow Rate 1 15.5 3 15.5 12.3 324.34 3.97 32332.11 2 18.5 6 18.5 12.5 342.35 4.197 34127.45 3 22 9.5 22 12.5 347.95 4.266 34685.69 4 29.5 15 29.5 13.3 348.17 4.138 34707.62 5 33.5 20 33.5 13.5 353.17 4.166 35206.05 6 36.5 23 36.5 13.5 359.65 4.2426 35852.02 7 42.5 28.25 42.5 14.25 372.68 4.279 37150.92 8 47 32 47 15 390.34 4.368 38911.38 9 51.5 36 51.5 15.5 393.91 4.337 39267.25 10 63 46 63 17 430.18 4.522 42882.86 Computations: where: Do = 14.25 mm = 0.01425 m dP = pg(Rm) Di = 28.5 mm = 0.0285 m Rm = upstream – downstream (manometric reading) pH2O = 997.08 kg/m3 Vo = Q/A A = [3.1416(0.01425)2]/4
  5. 5. Orifice: Co = 2.119 Trial 1: Trial 3: Rm = 43 mm – 2mm =41 mm Trial 2: Rm = 0.0466 m = 0.041 m Rm = 0.0452 m Vo = (346.15 ml/s x 1/1x106) Vo = (313.03 ml/s x 1/1x106) Vo = (345.63 ml/s x 1/1x106) 1.594849x10-4 m2 1.594849x10-4 m2 1.594849x10-4 m2 = 2.1704 m/s = 1.9628 m/s = 2.167 m/s dP = 997.08 kg/m3 (9.81 m/s) dP = 997.08 kg/m3 (9.81 m/s) dP = 997.08 kg/m3 (9.81 m/s) (0.0466 m) (0.041 m) (0.0452 m) = 455.811 Pa = 401.36 Pa = 442.117 Pa from the formula above: from the formula above: from the formula above: Co = 2.198 Co = 2.228 Venturi: (same eqn. used above) 40000 35000 30000 25000 y = 2E+06x 3 - 1E+07x 2 + 2E+07x - 2E+07 Re 20000 15000 10000 5000 0 2 2.05 2.1 2.15 2.2 2.25 Co Fig.1.1 shows the diagram of Re vs. Co for Orifice 50000 45000 40000 35000 30000 25000 20000 y = -28409x 3 + 384563x 2 - 2E+06x + 3E+06 15000 10000 5000 0 3.9 4 4.1 4.2 4.3 4.4 4.5 4.6
  6. 6. Fig.1.2 shows the diagram of Re vs. Co for Venturi Data Analysis : Based on the graph plotted above, the calibration of venturimeter is more accurate when measuring the rate of flow of a fluid through a pipe than an orifice meter. Care was handled with the reading of the manometer because only slight changes occur; a keen eye from the group member was needed. Several parameters were significant and recorded including the manometer readings in order to compute for the discharge coefficients. Recommendation: From the experiment, one main causes of error is due to the presence of bubbles within the hose and is assumed by the experimenter to be negligible. It really makes a big difference with respect to the rate of flow. Also, the orifice meter cannot measure directly the vertical displacement of the water stream at its varying distances. Application to ChE: Basically in industries, they are used for measuring the flow rate of chemicals through pipe. Both flowmeter is often used in applications where it's necessary with higher TurnDown Rates, or lower pressure drops. The Venturi meter which has long been used in hydraulics is applied to the measurement of volume flow of blood through vessels. One method is by inserting an accurately calibrated Venturi meter made of glass into the circulation. This method requires an anticoagulant, but is accurate and sensitive to slight changes in flow. Another method is to produce a constriction in a vessel by means of a ligature near a branch, which can be used as a side tube, thus transforming the vessel itself into a Venturi meter. The latter method is subject to greater error in calibration for absolute flows, but is sensitive for estimating slight changes in the rate of flow and does not require the use of an anticoagulant. They are also popular for automatic batching applications.

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