Flare Gas Metering Using Thermal Mass Flow Measurement
Critical industrial flare gas measurement for hazardous process and refinery environments.
Over 45 Years in Operation
1000's of UK Installations
Supporting 100's of UK Sites
The Challenge: Industrial Flare Gas Measurement
Flare systems are essential safety-critical infrastructure within oil & gas, petrochemical, refinery and industrial processing facilities.
They protect plants during:
- Process upsets
- Emergency shutdowns
- Pressure relief events
- Hydrocarbon venting conditions
However, flare gas metering is one of the most difficult gas flow applications in industry.
Typical challenges include:
- Extremely high turndown requirements
- High process temperatures
- Aggressive hydrocarbon gases
- Large pipe diameters
- Variable gas composition
- Hazardous area requirements
- Low pressure operation
- Rapid flow fluctuations during relief events
Reliable flare gas measurement is critical for both plant safety and environmental compliance.
The Solution: Thermal Mass Flare Gas Metering
Thermal mass flow measurement has become a proven solution for industrial flare gas metering due to its ability to directly measure gas mass flow across extremely wide operating ranges.
Unlike conventional differential pressure systems, thermal mass technology offers:
- Exceptional turndown capability
- Direct mass flow measurement
- Low pressure drop
- No moving parts
- Reliable operation across varying gas compositions
- Excellent low-flow sensitivity
This makes thermal mass flow meters highly suited to:
- Refinery flare systems
- Petrochemical flare stacks
- Hydrocarbon vent systems
- Process safety flare headers
- Steam-assisted flare systems
Why Industrial Flare Applications Are So Demanding
Industrial flare systems operate under highly dynamic and hazardous conditions.
During normal operation, flare lines may experience extremely low purge or pilot flows. During emergency relief events, flows can increase dramatically within seconds.
In addition, flare gases may include:
- Hydrocarbons
- Hydrogen
- Steam
- Corrosive gases
- High-temperature process gases
Instrumentation must therefore provide:
- Stable low-flow measurement
- High-flow survivability
- Hazardous area approvals
- Long-term reliability in harsh environments
Safety & Compliance Requirements
Flare gas metering is often closely linked to:
- Environmental emissions reporting
- EPA and regulatory compliance
- Process safety systems
- SIL/SIS applications
- Operational efficiency monitoring
In many industrial facilities, flare systems form part of critical safety infrastructure.
Instrumentation therefore needs to support:
- Hazardous area operation
- High integrity process monitoring
- Long-term stability and reliability
Recommended Technologies for Industrial Flare Systems
Thermal Mass Flow Meters
FCI thermal mass flow meters are widely used throughout industrial flare applications due to their robustness and high-performance measurement capability.
Key advantages include:
- Extremely high turndown ratios
- Direct mass flow measurement
- SIL-rated options available
- High temperature capability
- Hazardous area approvals
- Multipoint averaging technology for large ducts and stacks
Typical solutions include:
- ST100A
- MT100 multipoint thermal mass flow meters
Typical Industrial Applications
- Oil & gas processing
- Petrochemical plants
- Refineries
- Chemical processing facilities
- Power generation
- Hydrogen processing systems
- Industrial vent and relief systems
Integration with Wider Process Systems
Industrial flare gas metering systems are commonly integrated with:
- SIL/SIS instrumentation systems
- Combustion air flow measurement
- Process safety monitoring
- Hazardous area instrumentation
- Plant emissions reporting systems
Our Experience in Industrial Flow Applications
Allison Engineering supplies specialist thermal mass flow measurement solutions for some of the most demanding industrial gas flow applications.
We support customers with:
- Application engineering
- Hazardous area specification
- Flow meter selection
- Commissioning and optimisation
- Long-term technical support
See also:
- SIL & SIS Compliant Process Instrumentation
- Combustion Air Flow Measurement
- High Temperature Flow Measurement
- Hydrogen Flow Measurement
- Oil & Gas Industry Solutions
Key Benefits
- Exceptional turndown capability
- Reliable low-flow flare monitoring
- Suitable for hazardous industrial environments
- SIL-rated options available
- High temperature process capability
- Proven technology for critical flare applications
Need information or advice?
Speak with our friendly, expert team to discuss your requirements and find out how we can help you.
Flare Gas Metering FAQs
Explore common questions about flare gas measurement, including how it works, why it is challenging and how to select the right solution for your application.
What is flare gas metering?
Flare gas metering is the measurement of gas being burned in flare systems, typically used to safely dispose of excess hydrocarbons during normal operation or emergency conditions.
It is essential for emissions reporting, regulatory compliance and understanding process losses.
Why is flare gas difficult to measure?
Flare gas is difficult to measure due to wide flow ranges, low pressure, variable gas composition and harsh process conditions such as wet or contaminated gas.
These factors make accurate and stable measurement challenging for many technologies.
What is the best technology for flare gas measurement?
Thermal mass flow meters are widely used because they measure gas mass flow directly and perform well across wide turndown ranges and variable conditions.
The best solution depends on the application, pipe size and operating conditions.
What is turndown ratio and why is it important?
Turndown ratio refers to the range between the minimum and maximum measurable flow.
Flare systems require high turndown capability because they must measure both very low purge flows and high flow during flaring events.
Can flare gas measurement support emissions compliance?
Yes. Accurate flare gas measurement is essential for emissions reporting and compliance with regulations such as the EU Emissions Trading Scheme (EU-ETS).
Higher accuracy measurement systems support Tier 3 compliance requirements.
Can flow meters be verified without removal?
Some advanced flow meters, such as the ST100, include in situ calibration verification functions. This allows operators to check performance without removing the device from the process.
How do I choose the right flare gas meter?
Selection depends on pipe size, flow range, gas composition, pressure, temperature and regulatory requirements.
A detailed application review is the best starting point to ensure the correct solution is selected.
Relevant Links
Why Trust Allison Engineering
We are committed to delivering the highest standards across the specialist areas we support, combining proven products with practical engineering knowledge and dependable service.
Need Help with Flare Gas Measurement?
Speak to our team to identify the right solution for your flare gas application and ensure accurate, compliant and reliable measurement.