Panduan memilih tipe flow meter
After exploring how each flow meter works the way it does, learn more about which is the best fit for your needs and why. The price of the meter technology is one aspect to consider as well as installation and life cycle costs for the total ownership cost (includes factors such as footprint, flow conditioning, maintenance and calibration requirements).
1. Coriolis – $$$, total cost $$
Accuracy 0.05%
Advantages
Best measurement accuracy
Measures mass flow, liquid density and temperature
Flow profile insensitive
Unaffected by changes in temperature and pressure
Best rate of turndown
Suitable for gas, liquids, or slurry measurement
Able to measure high viscous fluids
Bi-directional
Low maintenance
Highly repeatable
Reliable
Disadvantages
Pressure drop might be higher (appropriate sizing mitigates)
Susceptible to severe system noise
Limited in large line sizes (>12″)
Low flow rates may result in lower measurement accuracy
Typical Applications
Custody transfer by mass and/or volume, precision batching, filling/dispensing, loading/unloading, continuous process control/monitoring, mass balance, density and/or concentration measurement, blending, utility metering, chemical injection, allocation, fuel consumption
2. Magnetic – $$, total cost $
Accuracy 0.15%
Advantages
Not constrained by Reynolds number or flow profiles
Immune to process variable changes such as temperature
High range of turndown
Negligible pressure loss with no obstructions
Able to handle large particles and chemicals
Not sensitive to variation in fluid velocity
Large line sizes
Variety of wetted path materials
Low power
Bi-directional
Disadvantages
Unable to measure gases and hydrocarbons
Typical minimum fluid conductance of 5 microsiemens (µS) required
Low conductivity versions available for fluid conductivities as low as 0.1 microsiemens (µS)
Electronics must be on same ground potential as the process
Use caution if installing near high voltage equipment to ensure proper meter isolation and process reference
Potential issues with electrode coating
Typical Applications
Conductive fluids in batching, filling/dispensing, continuous process control, utility metering, loading/unloading
3. Positive Displacement (PD) – $$, total cost $$
Accuracy 0.1%-2.0% depending on type
Advantages
Well understood and widely used technology
High turndown capacity
Suitable for high pressure applications
Relatively inexpensive and easy to install
Disadvantages
Frequent maintenance required
Potential for back flow from larger particle block
Inaccuracies
Typical Applications
Custody transfer by volume, batching, dispensing, allocation, chemical injection, fuel measurement, high pressure, hydraulic testing
4. Turbine – $, total cost $$
Accuracy 0.25%
Advantages
High accuracy and repeatability with clean fluids
High pressure and temperature tolerance
Fast response rate
Disadvantages
Two-phase flows may cause inaccuracies
Frequent maintenance required
Installation in small areas can be difficult
Wear out with non-lubricating fluids
Accuracy impacted by fluid characteristics (i.e. viscosity)
Typical Applications
Custody transfer by volume, batching, filling/dispensing, mass balance, blending, allocation, process control/monitoring
5. Ultrasonic – $$$, total cost $$$
Accuracy Wetted: 1% -2%, Non-invasive: 3% -10%
Advantages
Measures both liquids and gases
Reduced maintenance
No pressure drop
High turndown
Bi-directional
Large line sizes
Disadvantages
Partially filled pipes cause signal loss and lead to difficulty measuring
Transducer coatings can deflect beam and corrupt measurement
Process temperature can affect sound velocity and ultrasonic beam angle
Multiphase flow can cause error
Applications
Custody transfer by volume, precision batching, loading/unloading, continuous process control, mass balance, blending, utility metering, allocation
6. Vortex – $$, total cost $
Volumetric flow accuracy: 0.65% (liquid), 1.0% (gas)
Mass flow accuracy (temperature compensated): 2.0%
Advantages
2-wire configuration means lower cost
25%-40% reduced installation expense
Performs in extreme conditions
No field calibration required
Less leak potential, so fewer emissions
Wide flow range accuracy
No moving parts
Disadvantages
Not for low flow applications
Unsuitable for high viscosity fluids
Inaccurate in high vibration environments
Typical Applications
Steam, gas and liquid measurement in batching, filling/dispensing, continuous process control, utility metering
7. Differential Pressure (DP) flow – $, installed cost $$
Accuracy 1%
Advantages
Well understood and widely used technology
Established custody transfer and flow measurement standards
Wide variety of primary elements for multiple application suitability
Cost effective
Easy to calibrate in the field
Disadvantages
Consumes a large amount of available line pressure
Potentially difficult to install with flow conditioning straight pipe runs
Increased pumping and compression costs
Possible leak points due to traditional configuration
Typical Applications
Custody transfer by volume, batching, filling/dispensing, mass balance, blending, allocation, process control/monitoring, allocation
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