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Part II: flowmeter (SAMPLE BAR FLOWMETER)
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I SP bar flow measurement system
Flow measuring system is composed of throttling gear (differential pressure generator), differential pressure transmitter, flow totalizer and other secondary instruments. |
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Bottleneck in the development of flow measurement systems, making a high level of downstream instrumentation can not play its due high efficiency.
In the 1990s, the United States launched a new gun SNSP flow probe --SP bar, making the measurement accuracy of a source, repeatability and reliability reached a new height.
SP bar flow probe, differential pressure transmitter coupled Totalizer other secondary instruments, constitute the world's highest level of differential pressure |
| Functional SP bar flowmeter |
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Advantages
•Can be used to measure various media, wide range of application
•High precision, large range ratio
•Stable measurement signal, small fluctuation
•Low perpetual loss of pressure of pipeline
•Low installation cost, maintenance free
•Online installation and overhauling
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Advantages
•Can be used to measure various media, wide range of application
•High precision, large range ratio
•Convenient for verification
•Stable measurement signal, small fluctuation
•Low perpetual loss of pressure of pipeline
•Low installation cost, maintenance free
•Online installation and overhauling
•Suitable for media with high impurity content |
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Performance index
Measurement accuracy: ±1～1.5% Repeated accuracy: ±0.1% Applicable pressure: 0～32MPa Applicable temperature: -180℃～550℃
Upper range limit: according to probe strength Lower range limit: according to minimum differential pressure requirement Range ratio: >10: 1
Applicable pipe diameter: 32mm～9,000mm round tube, square tube Velocity measurement range (5-30)m/s
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Principle of measurement
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When the fluid flows through the probe, at its front portion to generate a high voltage distribution, slightly higher than the pressure of the static pressure distribution pipe.
According to the principle of Bernoulli equation, the speed of fluid flow through the probe to produce a low-rear distribution area in the probe, a pressure slightly lower than the static pressure of the low-pressure distribution pipe. After the flow of fluid from the probe to generate a partial vacuum in the rear portion of the probe, and the swirl in the sides of the probe.
Average rate of flow probe cross-sectional shape, surface roughness conditions and low pressure hole location is a key factor in the decision probe performance. Low signal stability and accuracy of precision and performance are the speed of the probe plays a decisive role.
SP bar flow probe can be accurately detected by the differential pressure of the fluid to an average of the average speed generated by the (functional detected differential pressure generated by the center of the flow rate).
SP bar standard flow probe in the high and low pressure area has much pressure holes arranged according to certain criteria to take to make it possible to accurately detect the average velocity. SP Pakistan functional flow probe in a high, piping centerline with a pair of low-pressure area to take pressure |
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Comparison of SP bar flowmeter standard type and functional type
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II Calculation formula of SP bar flowmeter:
SP bar flowmeter can measure flow velocity by measuring the difference of total pressure and static pressure of liquid. Output differential pressure (△p) and flow velocity (v) can be received from bernoullis equation
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Features and advantages
Simple structure, light weight
Convenient for installation and disassembly, low cost
Small loss of pressure, energy conservation
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This product can be used in various media, thus has wide range of application
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SP bar flowmeter traditional pore plate
Steam measurement comparison
| SP bar flowmeter |
Traditional pore plate |
| Steam measurement comparison |
| Liquid condition |
| Medium name: superheated steam; Flow condition: 40t/h; pressure: 1 (Mpa) |
Pipe size: 377/9.0mm; Density: 4.283kg/m ³; temperature: 300 (ºC) |
| Pore plate |
SP bar flowmeter |
β=0.6 δ=0.6×Dp W=Q×δ÷η
Fv=24×365×W×fv fv=0.8 Yuan/degree |
δ=0.03×Dp W=Q×δ÷η
Fv=24×365×W×fv fv=0.8 Yuan/degree |
| Dp=26.348Kpa |
Dp=2.439Kpa |
| δ=15.8088 Kpa Q=2.594m³/s |
δ=0.07317 Kpa Q=2.594m³/s |
| W=2.594×15.8088÷0.8=51.260(kw) |
W=２.594×0.07317÷0.8=0.237(KW) |
| Fv=24×365×51.260×0.8=359,230 Yuan/year (RMB) |
Fv=24×365×0.237×0.8=1,661 Yuan/year (RMB) |
| SP bar flowmeter can save operation cost 359230-1661=357,569(RMB) |
| Note:Dp=differential pressure value Kpa δ=fixed loss of pressure Kpa Q=volumetric flow of liquid m³/s motor efficiencyη=0.8 W =power lossKW fv=Electric chargeYuan/degree Fv Electric chargeYuan/degree |
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Gas measurement comparison
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| Liquid condition |
| Medium name: natural gas; flow condition: 1776 (m3/h); pressure: 1.6 (MPa) |
Pipe size: 273/8.0mm; density : 13.1273kg/ m3; temperature: 15°C |
| Pore plate |
SP bar flowmeter |
Β=0.5792 δ=0.6× Dp W=Q ×δ÷η
Fv=24 ×365× w× fv fv=0.8 Yuan/degree |
δ=0.03× Dp W=Q×δ÷η
Fv=24 ×365× w× fv fv=0.8 Yuan/degree |
| Dp=12.9621Kpa |
Dp=1.05318Kpa |
| δ=7.77726 Kpa Q=0.4933 m3/S |
δ=0.03159Kpa Q=0.4933 m3/S |
| W=0.4933×7.77726÷0.8=4.7931(KW) |
W=0. 03159×0.4933÷0.8=0.0195(KW) |
| FV=24×365×4.7931×0.8=33，590 Yuan/year (RMB) |
FV=24×365×0.0195×0.8=137 Yuan/year (RMB) |
| SP bar flowmeter can save operation cost 33590-137=33,453 Yuan (RMB) |
| Note: Dp=differential pressure value Kpa δ= fixed loss of pressure Kpa Q=volumetric flow of liquid m3/S motor efficiencyη=0.8 W=power lossKW fv=Electric chargeYuan/degree Fv=Electric charge Yuan/year |
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Liquid measurement comparison
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| Liquid condition |
| Medium name: water; flow condition: 380 (m3/h ); pressure: 1.6 (Mpa) Pipe size: 325/8.0(mm); Density: 1000 (kg/m3); temperature: 30 (°C) |
Pipe size: 325/8.0(mm); density: 1000 (kg/m3); temperature: 30 (°C) |
| Pore plate |
SP bar flowmeter |
β=0.5047 δ=0.6× Dp W=Q ×δ÷η
Fv=24 ×365× w× fv fv=0.8 Yuan/degree |
δ=0.03× Dp W=Q×δ÷η
Fv=24 ×365× w× fv fv=0.8 Yuan/degree |
| Dp=38.862Kpa |
Dp=1.7333Kpa |
| δ=23.3173Kpa Q=0.10556 m3/S |
δ=0.0520Kpa Q=0.10556 m3/S |
| FV=24×365×3.07672×0.8=21,561 Yuan/year (RMB) |
FV=24×365×0.007×0.8=49 Yuan/year (RMB) |
| SP bar flowmeter can save operation cost 21561-49=21, 512 Yuan (RMB) |
| Note: Dp=differential pressure value Kpa δ= fixed loss of pressure Kpa Q=volumetric flow of liquid m3/S motor efficiencyη=0.8 W=power lossKW fv=Electric chargeYuan/degree Fv=Electric charge Yuan/year |
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| Pipe section requirement |
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Standard type and functional type are suitable for straight pipe section:
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| Condition of pipeline |
Installation position |
Precision |
Front straight pipe section L1 |
Rear straight pipe section L2 |
| The front and the rear have double elbow pipeline |
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1% |
7D |
3D |
| 1.5% |
4D |
2D |
| The front and the rear have double elbow pipeline |
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1% |
7D |
3D |
| 1.5% |
4D |
2D |
| The front and the rear have double elbow pipeline |
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1% |
10D |
3D |
| 1.5% |
7D |
3D |
| There is shrinking/amplifying pipeline in front or in the rear |
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1% |
7D |
3D |
| 1.5% |
4D |
2D |
| There is amplifying/shrinking pipeline in front or in the rear |
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1% |
10D |
5D |
| 1.5% |
5D |
3D |
| There is control valve pipe in front |
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1% |
12D |
3D |
| 1.5% |
10D |
3D |
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Installation position of standard type and functional type:
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