Selecting the right flow metering technology for a given application can be daunting, especially considering the multitude of available options. In this blog, we will explore the advantages and disadvantages of various gas flow measurement technologies, helping process instrumentation engineers make the best decision that balances cost and performance.
There are several different technologies available when it comes to accurately measuring and monitoring the flow of fluids. These range from differential pressure-based orifice/averaging pitot tube/venturi/aerofoil to thermal mass-insertion type to Coriolis, vortex, turbine, and ultrasonic–clamp–on style. Each of these technologies has its advantages and disadvantages, making it essential to know the different flow measurement technologies available when deciding on the best one for a particular application. This blog post will explore the various flow measurement technologies available, their advantages and disadvantages, and how to determine which one is best for a given application.
Technology for Flow Measurement
- Differential Pressure-Based Flow Meter
- Thermal Mass – Insertion Type
- Coriolis
- Vortex
- Turbine
- Ultrasonic Clamp On Type
Important Factors to Consider for Optimum Selection
Technology selection is a crucial decision that organizations must make when determining which solutions best meet their needs. Unfortunately, there are numerous options to consider in many cases, and making the right choice can be difficult. Therefore, evaluating the various technologies on the market is essential to ensure that the optimal selection is made.
- Pipe sizes.
- Process situations which include glide rate, pressure, temperature, density, viscosity, dirt & moisture, etc.
- Installation conditions.
- Turndown ratio
- Cost
The selection of a fluid flow technology is a complex process that involves many variables. We can summarize the advantages and disadvantages of different flow technologies based on the above factors. However, it is ultimately up to the process engineer with some specific technology dominance or experience.
DIFFERENTIAL PRESSURE-BASED FLOW METER
Benefits
- Standard BS-1042/ISO5167.
- Suitable for 15mm to 10mtrs or higher.
- Rugged design.
- Can be oriented in any direction.
- Highly repeatable.
- Low cost up to 300mm pipe size.
- Easy site calibration.
Limitations
- High-pressure drop
- Require periodic maintenance
- Lower Accuracy 3% FSD.
- Low turndown ratio 4:1
- Low flow sensitivity.
- Susceptive to clogging.
- Higher wear factor.
THERMAL MASS FLOW METER – INSERTION TYPE
Benefits
- Works on steady temperature anemometry.
- Suitable up to 15mm to 10000mm pipe size.
- Rugged insertion and works up to 400⁰C & 16bar or more
- Can be oriented in any direction.
- Accuracy ±2%RD.
- 100:1 turndown ratio
- Adjustable and versatile.
- Low pressure-drop
- Low cost above 100mm pipe sizes
Limitations
- Vulnerable to damage mechanically.
- Easily affected by turbulence & vibrations
- Flow straightener needed.
- Susceptible to high moisture.
CORIOLIS FLOWMETER
Benefits
- Direct mass flow rate
- Suitable for 2mm up to 300mm pipe size
- High-pressure up to 400bar or higher
- Can be oriented in any direction.
- Highest accuracy (±0.1%- ±0.5%RD).
- (±0.02%)
- Turn-down ratio of 100:1 or higher.
Limitations
- High-pressure drop.
- Not suitable for pipe larger than 300mm.
- Not suitable for temperatures above 120⁰C.
- Susceptible to vibrations.
- High initial cost.
VORTEX FLOWMETER
Benefits
- Determines volumetric flow rate using vortices and frequency dimension·
- Suitable for 15mm up to 300mm.
- Horizontal or a vertical orientation is possible.
- Suitable for up to 300⁰C temperature & pressure up to 40bar
- Better accuracy (±1.5%RD).
- (±0.02%)
- Low Initial cost up to 80mm size
Limitations
- Higher strain drop
- Turndown ratio of 10:1
- Installation needs utmost care.
- Prone to vibrations & turbulence
- Require periodic maintenance
- High Initial fee for 100mm & above size
TURBINE FLOWMETER
Benefits
- Derives volumetric flow rate by moving the rotating turbine frequency.
- Suitable for up to 6mm to 300mm.
- Fit for excessive strain up to 250 bar & temperature as much as 200⁰C.
- High accuracy (±1% RD).
- (±0.25%)
- Low initial cost.
Limitations
- Gas has to be dry and clean.
- Moving parts need periodic maintenance.
- High wear factor.
ULTRASONIC FLOWMETER – CLAMP-ON TYPE
Benefits
- Utilizes ultrasonic beam transit-time measurement to determine volumetric flow rate – Non-Intrusive & Fixed·
- Suitable for 10mm up to 1600mm pipe size.
- Fits high pressures of 200 bar and temperatures of up to 2000°C.
- Horizontal or vertical orientation possible
- Better accuracy (±1%-3% RD).
- (±0.25%)
- Turn down ratio higher than 100:1
- Minimal installation cost.
Limitations
- Gas needs to be dry and clean.
- High initial cost.
- Installation requires proper technical knowledge.
- Not suitable for pipes with inner lining.
Conclusion
Flow measurement is a critical part of the process. With that in mind, we’ve put together this list of pros and cons of each type of flow measurement principle so that you can make an informed decision about which one will work best for your specific needs.
