SL40 Flow Rate Measurement

Transcription

1 SL40 Flow Rate Measurement ESS3271 Lecture V-notch weir Pump Rotameter Vortex Shedding Optical sensing Electro-magnetic sensing

2 V-Notch Weir (1) (2)

3 Rotameter Very commonly used Drag force = weight + buoyancy force Area meter Elevation of the bob = f(annular area between bob & tapered glass tube) Physical principle: force balance on the bob C d = f(re) = f(u m Lρ/μ) Special bob => essentially independent of viscosity For many cases, the quadratic area relation becomes nearly linear for actual dimensions of the tube and bob C 1 = appropriate meter constant

4 Rotameter C d = f(re) = f(ρu m L/μ) Special bobs => constant drag coefficient In practical, the quadratic area relation becomes nearly linear for actual dimensions of the tube and bob C 1 : an appropriate meter constant For gas flow PV = NRT R = J/mol K P RT N Nm ρ = = = V Vm m m air = kg/mol Q

5 Vortex Shedding Flowmeters Bluff body => shedding vortices Frequency of vortex shedding liquid velocity Piezoelectric sensor mounted inside the vortex shedder detects the vortices + subsequent amplification circuits for instantaneous flow rate or totalized flow over a selected time interval Unsuitable for use with highly viscous liquids Strouhal number, S = f s d/u f s : shedding frequency, d: diameter or characteristic dimension of the bluff body, u: velocity S~0.88: 1% variation for 10 4 < Re < 10 6 Can also be used to construct velocity probe for local velocity measurement A vortex (pl. vortices) is a spinning, often turbulent, flow of fluid

6 Hot-Wire Anemometer Study rapidly varying flow conditions Electrically heated and placed in the flow stream Thermal equilibrium q o = q i q o = (a+bu 0.5 )(T w -T ) u: fluid velocity, T w : wire temp, T : free stream temp of fluid q i = i 2 R w = i 2 R o [1+α(T w -T o )] i and R w determined => u can be calculated transient response of both the thermal and electrical resistance characteristics of the wire time constant ~ 1 ms for diameter platinum or tungsten wires operating in air constant-current or constant-temperature arrangement Response of the wire depends on Flow angle L/d (typically ~50)

7 Magnetic Flowmeters Induced voltage E = BLu x 10-8 V Conducting fluid flows through a magnetic field B: magnetic flux density, gauss u: velocity of the conductor ( mean flow velocity) L: length of the conductor ( tube diameter) Magnetic Flowmeters Two types are used commercially For low-conductivity fluids (like water) non-conducting pipe liner electrodes are flush with the liner and make contact with the fluid AC (DC pulsed) magnetic field For high-conductivity fluids (like liquid metals) stainless-steel pipe electrodes are attached to the outside of the pipe and diametrically opposed to each other output is sufficiently high

8 Experiments 1. Rotameter 2. V-notch weir 3. Optical sensing (impeller) 4. Vortex shedding 5. Airflow sensing Electro-magnetic sensing V-Notch Weir

9 Optical Sensing Propeller sensing Electro-magnetic sensing

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11 實驗原理 Rotameter + V-Notch Weir + Vortex Shedding 相關問題 請比較 V-Notch Weir 和 Rotameter 兩者讀值的差異, 並說明造成此一差異的原因 請說明若水中帶有雜質 ( 例如直徑 1mm 的固體顆粒 ) 時, 對實驗結果可能造成的影響

12 VF-2000 Vortex Flow Sensor for Water The VF-2000 Flow Sensor offers a cost-effective instrument for the measurement of liquid flow. A simple and compact design makes the VF-2000 a good choice for the measurement of water, pure water, cooling water. Current output model, Pulse output model and Display model with current / alarm outputs are available. Features Simple and Compact Design The VF-2000 Flow Sensor is assembled with a few pieces of components. The sensor body and Shedder bar (vortex generator) are molded as one component. This design approach has reduced the cost as well as the size and weight of the flowmeter. Sensor body is made of PPS (Polyphenylene sulfide) and is designed to eliminate deposits. No Maintenance Cost Since the VF-2000 has no moving parts, no maintenance is needed. Low Pressure Loss A combination of straight flow path and Shedder bar gives a lower pressure loss compared with other types of flowmeters. Display Model with Current and Alarm Output 3-digit LED display for flow rate, current output and alarm outputs (2-point) are provided in compact design. CE Marking The VF-2000 meets the EC directive for CE mark. Operating Principle A bluff body or Shedder bar in the flow generates a street of vortices downstream. The VF-2000 Flow Sensor measures the flow rate by counting the number of vortices with a piezoelectric sensor. Shedder bar Sensor Vortices Piezoelectric element Figure 1 Construction VF-201 VF-202 FLOW Figure 2 Part No. Name 1 Sensor body 2 Shedder bar (cast with Sensor body) 3 Sensor 4 O-ring 5 Cover TG-ES886-2E Sep. 2000

13 VF-2000 Vortex Flow Sensor Specifications Specifications Measurable Fluid Accuracy *1 Additional Error for LED Display Repeatability Fluid Pressure Fluid Temperature Ambient Temperature Ambient Humidity VF-20 1 Flow Range: VF-20 2 Conn. Size *1 VF-20 3 Power Supply Rated Power Flowrate Display Alarm VF-2031 Display VF-2032 Resolution VF-2033 Output Damping Time Constant Cable Mass Meter Cable Enclosure Classification Min. Straight Pipe Run VF-20 1 Process Connection VF-20 2 VF-20 3 Materials Wetted part Sensor body Sensor O-ring Cover Cable sheath Model Current Output Model Pulse Output Model Display Model VF-201 VF-202 VF-203 Pure water, Water 3%F.S. - 1digit 0.5%F.S 0 to 1MPa 0 to 70 o C 0 to 70 o C (Refer to Figure 3) 0 to 50 o C 0 to 50 o C (Refer to Figure 3) 5 to 90%RH 0.5 to 4 L/min or 0.13 to 1 GPM: 3/8" 2 to 16 L/min or 0.5 to 4 GPM: 1/2" 4 to 40 L/min or 1 to 10 GPM: 1/2" Rated voltage: 12 to 24 VDC Operating voltage: 10.8 to 26.4 VDC 1W 0.5W 2W - 3-digit LED - 2 LED (Alarm-1, Alarm-2) L/min or 0.01 GPM - 0.1L/min or 0.01 GPM L/min or 0.1 GPM Current output Unscaled pulse output Current output 4 to 20mA (3-wire) Open collector, 4 to 20mA (3-wire) Load: Max. 10mA/30VDC Load: 0 to 250 ohms at 12VDC Pulse duty factor; approx. 50% 0 to 250 ohms at 12V DC 250 to 600 ohms at 24VDC Output frequency at 100% flow 250 to 600 ohms at 24V DC (Refer to Figure 6) VF F01 800Hz at 4L/min (Refer to Figure 6) VF F02 757Hz at 1GPM Alarm output VF F01 800Hz at 16L/min Alarm-1 and Alarm-2 VF F02 757Hz at 4GPM Open collector, VF F01 584Hz at 40L/min Max. 80mA/30V DC VF F02 553Hz at 10GPM Hysterisis; equal to display resolution 1 sec (63% response) 0.2mm 0.2mm 2 x 3C (AWG24), 3m, Outside diameter 3.5mm 2 x 5C (AWG24), 3m, Outside diameter 4.5mm, (Soldered end finish) (Soldered end finish) 60g 80g 75g 90g IP64 Upstream : 10D, Downstream : 5D (D : Nominal pipe size) Taper pipe threads (JIS B 0203 / ISO 7/1) : R3/8" Taper pipe threads (JIS B 0203 / ISO 7/1) : R1/2" Taper pipe threads (JIS B 0203 / ISO 7/1) : R1/2" Polyphenylene sulfide (PPS) Piezoelectric element molded with PPS Fluorine rubber (FKM) Poly-butylene trephthalate (PBT) Heat- resistant PVC *1Conditions for calibration Fluid : Water, Fluid temperature : 20 o C Ambient temperature : 23 o C, Supply voltage : 24 VDC 2 TOKYO KEISO CO., LTD. TG-ES886-2E

14 VF-2000 Vortex Flow Sensor Fluid and Ambient Temperature Range (only for Display type VF-203 ) Operating range Fluid Temperature ( o C) Ambient Temperature ( o C) Figure 3 Wiring Diagram Current Output Model (VF-201 ) [Brown] Pulse Output Model (VF-202 ) [Brown] [Black] 4 to 20mA DC [Blue] + Load to 26.4V DC - [Black] + Pulse output [Blue] to 26.4V DC - [Shield] Display / Current Output Model (VF-203 ) [Brown] Model Code [White] [Gray] [Black] + 4 to 20mA DC [Blue] Load - [Shield] Figure Alarm 2 Alarm to 26.4V DC - Load Resistance Range Load Resistance [Shield] (ohm) 600 Operating Range (V DC) Supply Voltage Figure 5 Model Code Description VF Current output : 4 to 20mA DC 2 Pulse output : Open collector (Unscaled) Type/Output Display : Flow rate (3-digit LED), Alarm (2 LED) 3 Current output : 4 to 20mA DC Alarm output : Open collector (2 points) Nominal Size : 1 6 mm : L/min or GPM ; 3/8" Flow Range ; 2 10 mm : 2-16 L/min or 0.5-4GPM ; 1/2" Connection Size 3 15 mm : 4-40 L/min or 1-10GPM ; 1/2" O-ring Material - F Fluorine rubber (FKM) Process Connection 0 Taper Pipe Threads R3/8 or R1/2 (JIS B 0203 / ISO 7/1) 1 L/min Flow Unit 2 GPM Accessory Code /RCT /NPT Model Code Example : VF-2011-F01 / NPT Rc / Rc (Internal thread) Adapter [Material : 316 Stainless Steel] Rc / NPT(Internal thread) Adapter [Material : 316 Stainless Steel] TG-ES886-2E TOKYO KEISO CO., LTD. 3

15 VF-2000 Vortex Flow Sensor Outline Dimensions VF-201 VF-202 VF SET AL 2 L /min AL 1 VORTEX FLOW SENSOR D D FLOW FLOW Model Thread D VF-201 R3/8 VF-202 R1/2 VF-203 R1/2 Figure 6 Adapter Width across flat B D1 D2 VF-2000 Model L B D1 D2 Mass(g)/1pc. VF Rc3/8 or 3/8NPT Rc3/8 50 L VF-202 VF Rc1/2 or 1/2NPT Rc1/2 85 Figure 7 Ordering Instructions Specify the following when ordering: 1. Model code 2. Fluid name *Specification subject to change without notice Head Office : Shiba Toho Building, Shibakoen, Minato-ku, Tokyo Tel : (KEY) ; Fax : overseas.sales@tokyokeiso.co.jp ; URL : 4 TG-ES886-2E

16 Airflow Sensors Microbridge Mass Airflow/Amplified AWM3000 Series Figure 1 Heater control circuit FEATURES Laser trimmed for improved sensor interchangeability Flow sensing up to 1.0 SLPM Low differential pressure sensing Like the AWM2000 Series, the dual Wheatstone bridges control airflow measurement. The AWM3000 Series is amplified; therefore, it can be used to increase the gain and to introduce voltage offsets to the sensor output. The schematic in Figure 3 depicts the amplification circuitry on board the sensor. Also, the heater control circuit (see Figure 1) and the sensing bridge supply circuit (see Figure 2) are on board the package. Figure 2 Sensing bridge supply circuit Airflow Figure 3 Differential instrumentation amplifier circuit Honeywell Sensing and Control USA International Canada 71

17 Airflow Sensors Microbridge Mass Airflow/Amplified AWM3000 Series AWM3000 SERIES ORDER GUIDE (Performance ±0.01 VDC, 25 C) Catalog Listings AWM3100V AWM3150V AWM3200V AWM3300V Flow Range (Full Scale) +200 sccm +30 sccm sccm Pressure Range (See Application Note 1) +2.0 H2O (5 mbar) Output Trim Point sccm sccm 5 2 H2O sccm Null Voltage 1.00 ±0.05 VDC 1.00 ±0.10 VDC 1.00 ±0.08 VDC 1.00 ±0.10 VDC Null Voltage Shift, Typ. +25 to 25 C, 25 to +85 C ±25 mv ±100 mv ±25 mv ±25 mv Output Voltage Shift, Max. +25 to 25 C 4% Reading ±5% Reading +24% Reading (Note 3) 5% Reading +25 to +85 C +4% Reading ±5% Reading 24% Reading +5% Reading Repeatability & Hysteresis, Max. ±0.50% Reading ±1% Reading ±0.50% Reading ±1% Reading Min. Typ. Max. Excitation VDC (Note 2) ± Power Consumption (mw) Response Time (msec) (Note 1) Common Mode Pressure (psi) 25 Temperature Range Operating: 25 to +85 C ( 13 to +185 F); Storage: 40 to +90 C ( 40 to +194 F) Termination 2,54 mm (.100 ) centers, 0,635 mm (0.025 ) square Weight (grams) 10.8 Shock Rating 100 g peak (5 drops, 6 axes) Notes: 1. Initial warm-up time for signal conditioned circuitry is 1 minute max. 2. Output Voltage is ratiometric to supply voltage. 3. Temperature shifts when sensing differential pressure correlates to the density change of the gas over temperature. (See Application Note 1.) 4. Maximum allowable rate of flow change to prevent damage: 5 SLPM/1 sec. MOUNTING DIMENSIONS (for reference only) Note: Positive flow direction is defined as proceeding from Port 1 (P1) to Port 2 (P2) and results in positive output. Do not exert a force greater than 4.54kg (10 lbs.) in any direction. 72 Honeywell Sensing and Control USA International Canada

18 Airflow Sensors Microbridge Mass Airflow/Amplified AWM3000 Series OUTPUT FLOW VS INTERCHANGEABILITY (Note 1) Performance 10.0 ±0.01 VDC, 25 C AWM3100V AWM3150V AWM3200V (Note 2) AWM3300V Press. Flow Nom. Tol. Press Flow Nom. Tol. Flow Press Nom. Tol. Press. Flow Nom. Tol. mbar sccm VDC ± VDC mbar sccm VDC ± VDC sccm H 2 O VDC ± VDC mbar sccm VDC ± VDC Notes: 1. Numbers in BOLD type indicate calibration type, mass flow or differential pressure. Tolerance values apply to calibration type only. 2. Differential pressure calibrated devices are not recommended for flow measurement. Use flow calibrated devices for flow measurement. OUTPUT CURVES Airflow Honeywell Sensing and Control USA International Canada 73

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