# nuflo gas flowmeter manual

NUFLO TM 2-inch Gas Flowmeter User Manual Manual No. 9A-100079591, Rev. 01 © 2009 Cameron International Corporation (“Cameron“). All information contained in this publication is confidential and proprietary property of Cameron. Any reproduction or use of these instructions, drawings, or photographs without the express written permission of an of- ficer of Cameron is forbidden. All Rights Reserved. Printed in the United States of America. Manual No. 9A-100079591, Rev. 01 September 2009September 2009 iii Table of Contents Section 1—Introduction . 5 Operating Principles .5 Specifications 6 Section 2—Setup and Calibration . 11 Installation 11 Calibration of Electronic Readout Equipment 11 Absolute Pressure and Temperature .12 Calculating Gas Volume in Actual Cubic Feet .12 Calculating Gas Volume in Standard Cubic Feet 13 Determining the Divisor for Readout in Standard Cubic Feet .13 Effects of Supercompressibility .14 Calibrating Equipment for Readout in Standard Cubic Feet Per Unit of Time 14 Effects of Fluctuating Temperatures 15 Effects of Fluctuating Pressures 16 Section 3—Maintenance . 21 Removing and Replacing Cartridges.21 Flowmeter Assemblies 22 Spare Parts.22 Accessories .22iv September 2009 September 2009 5 Section 1 Introduction The NuFlo 2-in. Gas Flowmeter is a turbine flowmeter, housed inside an insert element that is placed between two raised-face flanges. Continuous stud bolts draw the flanges together against the housing element, and gaskets on the face of the flanges and meter body help ensure a competent seal. Bolts, nuts, and gaskets are available as part of an optional hardware installation kit. All internal components—the rotor and shaft assembly, bearings, and setscrews—are contained within a car- tridge inside the meter. Three different cartridges are available to accommodate high, standard, and low flow ranges (see Figs. 1.2 through 1.4, pages 3 through 5). An electromagnetic pickup screwed into the receptacle on the side of the meter produces the output signal. Figure 1.1—Flowmeter components Operating Principles The gas to be measured is flowed through the meter. As the gas passes the rotor, it impinges against the pitched rotor blade, causing the rotor to spin at a speed directly proportional to the velocity of the gas stream. As the rotor spins, its blades interrupt the magnetic field set up by the pickup. This interruption induces a voltage in the coil of the pickup. The readout instrument senses this voltage pulse and converts it into a usable form that indicates gas volume.6 September 2009 Specifications Size 2-in. (50.8 mm) End Connections Flowmeter installs between two raised face flanges Working Pressure 0 to 2220 psig (15,306 kPa) Nominal Calibration Factor Low Range 325 p/ACF (16600 p/m3) Standard Range 125 p/ACF (4415 p/m3) High Range 70 p/ACF (2472 p/m3) Output Frequency 5 to 320 Hz over rated range Output Voltage 30 mV peak to peak at 5 Hz, 900 mV peak to peak at 320 Hz Pressure Drop Less than 1-in. (24.5 mm) water column at maxi- mum rated flow Linearity +/- 2% of reading Repeatability +/- 0.5% of reading Temperature 0º to 225ºF (-18º to 107ºC) Pickup Connector Mates with AN3106A-10SL-4P Conduit Connection 1-in. (25.4 mm) Pressure Tap 1/8-in. NPT (3.2 mm) Compliances CSA Certified Hazardous locations Class I, Groups A, B, C, D, Div. 1, ANSI 12.27.01-2003 Single Seal Certified by Cameron in compliance with pre- qualified materials of NACE MR0175/ISO 15156. This certification does not imply or warrant the application of the product in compliance with NACE MR0175/ISO 15156 service conditions in which the customer/user installs the product.September 2009 7 Figure 1.2—High gas flow range where Q (.6) = Flow rate on graph at operating pressure G = Sp. Gr. of other gas Q (g) = Flow rate for other gas Flow rate ranges are based on 0.6 Sp. Gr. gas. To determine capacity for other gases, use: 2832000 1416000 566400 283200 141600 56640 28320 14160 5664 2832 1416 566.4 283.2 141.6 56.6 28.3 2000 (13800) 1000 (6900) 500 (3450) 200 (1380) 100 (690) 50 (345) 20 (138) 10 (69) 5 (34.5) 2 (13.8) 1 (6.9) 1 2 5 10 20 50 100 200 500 1000 2000 5000 10000 20000 50000 100000 CU.M/DAY MCFD (SCFM) (69444.4) (34722.2) (13888.9) (6944.4) (3472.2) (1388.9) (694.4) (347.2) (138.9) (69.4) (34.7) (13.9) (6.9) (3.5) (1.4) (0.7) FLOWINGPRESSURE,PSIG(kPa) (.6) (g) 0.6 Q Q = G8 September 2009 Figure 1.3—Standard gas flow range where Q (.6) = Flow rate on graph at operating pressure G = Sp. Gr. of other gas Q (g) = Flow rate for other gas Flow rate ranges are based on 0.6 Sp. Gr. gas. To determine capacity for other gases, use: 2832000 1416000 566400 283200 141600 56640 28320 14160 5664 2832 1416 566.4 283.2 141.6 56.6 28.3 2000 (13800) 1000 (6900) 500 (3450) 200 (1380) 100 (690) 50 (345) 20 (138) 10 (69) 5 (34.5) 2 (13.8) 1 (6.9) 1 2 5 10 20 50 100 200 500 1000 2000 5000 10000 20000 50000 100000 CU.M/DAY MCFD (SCFM) (69444.4) (34722.2) (13888.9) (6944.4) (3472.2) (1388.9) (694.4) (347.2) (138.9) (69.4) (34.7) (13.9) (6.9) (3.5) (1.4) (0.7) FLOWINGPRESSURE,PSIG(kPa) (.6) (g) 0.6 Q Q = GSeptember 2009 9 Figure 1.4—Low gas flow range where Q (.6) = Flow rate on graph at operating pressure G = Sp. Gr. of other gas Q (g) = Flow rate for other gas Flow rate ranges are based on 0.6 Sp. Gr. gas. To determine capacity for other gases, use: 2832000 1416000 566400 283200 141600 56640 28320 14160 5664 2832 1416 566.4 283.2 141.6 56.6 28.3 2000 (13800) 1000 (6900) 500 (3450) 200 (1380) 100 (690) 50 (345) 20 (138) 10 (69) 5 (34.5) 2 (13.8) 1 (6.9) 1 2 5 10 20 50 100 200 500 1000 2000 5000 10000 20000 50000 100000 CU.M/DAY MCFD (SCFM) (69444.4) (34722.2) (13888.9) (6944.4) (3472.2) (1388.9) (694.4) (347.2) (138.9) (69.4) (34.7) (13.9) (6.9) (3.5) (1.4) (0.7) FLOWINGPRESSURE,PSIG(kPa) (.6) (g) 0.6 Q Q = G10 September 2009 September 2009 11 Section 2 Setup and Calibration Installation The NuFlo Gas Flowmeter must be installed properly to prevent gas from swirling or experiencing other er- ratic flow characteristics. Figure 2.1 shows the proper installation of the meter. *10 nominal pipe diameters is the minimum recommended upstream pipe length. If a flow straightener is not used, longer upstream pipe lengths may be required to minimize measurement uncertainty due to swirl or asymmetrical flow. Figure 2.1—Typical installation of an in-line gas turbine meter (minimum lengths). Upstream and downstream sections are available in Schedule 40 and Schedule 80 pipe. Calibration of Electronic Readout Equipment Before a flowmeter leaves the factory, it is calibrated at multiple points within the flow range of the cartridge; the factor is given in pulses per actual cubic foot (acf). This factor, which is recorded on a calibration tag that is attached to the meter, is then used to calibrate electronic readout equipment in the field. Fluid measured by the gas turbine meter is compressible, and is also affected by temperature changes. The volumetric change caused by temperature and/or pressure for any ideal gas follows the equation below: 1 1 2 2 1 2 P V P V T T =12 September 2009 Absolute Pressure and Temperature The equation above shows that the volume of gas is determined by pressure and temperature. In this equation, the pressure, P, is absolute pressure (the flowing or observed gauge pressure plus the atmospheric pressure). The commonly used unit of measure for absolute pressure is pounds per square inch absolute (psia). For this purpose, atmospheric pressure is considered to be 14.73 psi. Therefore, Absolute pressure (psia) = Observed gauge pressure (psig) + 14.73 psi The absolute temperature in the equation above is expressed in degrees Rankine, which is calculated as fol- lows: Degrees Rankine = Flowing gas temperature (°F) + 459.67 Calculating Gas Volume in Actual Cubic Feet As a point of reference for discussing volumetric units of gas, one cubic foot (1ft 3 ) of gas at a pressure of 1 atmosphere (assume 14.73 psia) at a temperature of 60°F (519.69°R) is considered one standard cubic foot (scf). A cubic foot of gas at any other pressure and temperature is referred to as an actual cubic foot (acf) and has no significance unless the conditions of pressure and temperature are known. For example, given 1 acf of gas at 200 psig at 100°F, the volume of gas at standard conditions may be calculated with the following formula: ( ) ( ) 3 3 3 standard pressure volume observed pressure 1 ft standard temperature observed temperature 200 14.73 1 ft 14.73 volume 519.67 100 459.67 214.73 519.67 Volume 559.67 14.73 Volume 13.536 ft × × = + × × = + × = × = Therefore, 1 ft 3 of gas at 200 psi and 100°F would occupy a volume of 13.536 ft 3 if the pressure and tem- perature were reduced to standard conditions of 0 psi (14.73 psia) and 60°F. Numerous laboratory tests have shown that the NuFlo Gas Flowmeter produces the same number of pulses per actual cubic foot of gas regardless of the pressure and temperature of the gas when operated within its rated range. As a result, the calibration factor can be specified in pulses per actual cubic foot. If the readout equipment for a gas meter and the totalizer register in actual cubic feet, the flow totalizer divisor is set to the nearest whole number to the calibration factor. The counter will then register actual cubic feet, regardless of the flowing pressure and temperature. Example: Assume a 2-in. gas flowmeter with a calibration factor of 124.96 pulses per actual cubic foot, a flowline pressure of 70 psig, and a temperature of 80°F. If the readout equipment divisor is set for 125, totalizer measurements will be in actual cubic feet; if the readout equipment divisor is set for 1,250, totalizer measurements will be in tens of actual cubic feet.September 2009 13 Calculating Gas Volume in Standard Cubic Feet Generally, gas is measured in standard cubic feet rather than actual cubic feet. Remember, at standard condi- tions (0 psi and 60°F), standard cubic feet and actual cubic feet are equivalent. To convert actual cubic feet to standard cubic feet, use the following formula: f s s f Actual Cubic Feet P T Standard Cubic Feet P T × × = × where P f = flow pressure (psia) P s = standard pressure (14.73 psia) T f = flowing temperature (°R) T s = standard temperature (519.67°R) Example How many standard cubic feet are in each actual cubic foot at a flowing pressure of 70 psig and a flowing temperature of 80°F? ( ) ( ) 1.0 70 14.73 519.67 Standard Cubic Feet 5.539 14.73 80 459.67 × + × = = × + The example above shows that there are 5.539 scf in every actual cubic foot at the flowing conditions of 70 psi at 80°F. The number of standard cubic feet may be obtained by setting the flow totalizer for the calibration factor of the gas meter as previously described, and multiplying the registration by 5.539. Example A 2-in. gas turbine flowmeter with a calibration factor of 124.36 pulses per actual cubic foot is installed in a flowline operating at 70 psig at 80°F. The flow totalizer divisor is set at 1,244 for registration in tens of actual cubic feet. Assume that during a 24-hour period, the totalizer registers 2,327 counts. How many standard cubic feet were metered during this period? Standard cubic feet = 2327 × 10 × 5.539 = 128,893 Determining the Divisor for Readout in Standard Cubic Feet If the flowing conditions are kept constant, the multiplier for converting actual cubic feet to standard cu- bic feet will also remain constant. To simplify operations, consider this when computing the divisor for the readout equipment and provide a direct readout in standard cubic feet. The following formula can be used to determine the divisor for any given set of operating conditions: s f f s FCF P T Divisor P T × × = ×14 September 2009 where FCF = flowmeter calibration factor (pulses/acf) P s = standard pressure (14.73 psia) P f = flowing pressure (psia) T f = flowing temperature (°R) T s = standard temperature (519.67°R) Example A 2-in. gas turbine meter has a calibration factor of 124.36 pulses per actual cubic foot, and is installed in a flowline operating at 70 psi at 80°F. Calculate the divisor for a flow totalizer to register in standard cubic feet. ( ) ( ) 124.36 14.73 80 459.67 Divisor 22.452 70+14.73 519.67 × × + = = × A divisor of 224 should be used for readings in tens of standard cubic feet, a divisor of 2,245 should be used for readings in hundreds of standard cubic feet. Effects of Supercompressibility The procedures described in this manual are applicable only when the flowing pressure and temperature remain constant at the values used in the computation. If an application has a line pressure greater than 200 psig, the operator should consider the effects of supercompressibility and adjust the divisor accordingly. The equation for calculating a divisor that allows for supercompressibility is s f 2 f s pv FCF P T Divisor = P T (F ) × × × × where F pv = supercompressibility factor Calibrating Equipment for Readout in Standard Cubic Feet Per Unit of Time The readout equipment’s flow rate indicator and/or analog rate output may also be calibrated for the flowing conditions to provide registration in standard cubic feet per unit of time. The rate indicator will produce the full-scale output selected when the gas turbine meter generates the fre- quency corresponding to that output. The following formula may be used to calculate the full-scale frequency for any particular readout device: s f f s FSFR FCF P T FSF TBCF P T × × × = × ×September 2009 15 where FSF = full-scale frequency (Hz) FSFR = full-scale flow rate (scf/unit time) FCF = flowmeter calibration factor (pulses/acf) P s = standard pressure (14.73 psia) T f = flowing temperature (°R) TBCF = time-based conversion factor (seconds/unit time) P f = flowing pressure (psia) T s = standard temperature (519.67°R) Example Calculate the full-scale frequency for the readout in the previous example if the full-scale flow rate is 1,500 Mscf/D. ( ) ( ) 1 ,500,000 124.36 14.73 80 459.67 FSF 389.78 Hz 24 hr 60 min 60 sec 70+14.73 519.67 day hr min × × × + = = × × × × The readout device should indicate 1500 Mscf/D flow with a 389.78 Hz signal fed into the flowmeter signal input. Effects of Fluctuating Temperatures In some applications, temperature does not remain constant and the operator must determine to what degree changing temperatures affect readout accuracy. In many cases, changes in temperature will not produce seri- ous measurement errors and can often be ignored. However, where temperature changes are more extreme, the user may recalibrate the readout equipment seasonally to offset the impact of wide ranges of temperature changes from summer to winter. Figure 2.2 illustrates how fluctuations in flowing temperature cause errors in standard cubic feet. To determine the effect of temperature changes on readout accuracy, see the example below. A 2-in. gas turbine flowmeter is installed in a flowline operating at 70 psig at 80°F. At standard conditions, 1 ft 3 of gas will occ