Stack Flow Meter
Averaging Pitot Tube (APT) Based Stack Flow Metering System — for flue gas & industrial monitoring
Stack Flow Meter
Our Averaging Pitot Tube (APT) Based Stack Flow Metering System is a robust, low-maintenance flow measurement solution designed for accurate velocity and volumetric flow measurement of flue gas, stack emissions, and large-diameter duct flows. Using multi-port averaging pitot tube sensors installed across the full line size of the stack or duct, the system captures a representative velocity profile across the cross-section, delivering accurate differential-pressure-based flow measurement even in large ducts, low-pressure-drop applications, and CEMS (Continuous Emissions Monitoring System) installations.
The pitot tube material of construction is selected based on the process gas composition, temperature, and dust/particulate loading, ensuring long service life in corrosive or abrasive flue gas streams. For applications involving highly dusty or particulate-laden media, an optional auto-purge system is available to keep sensing ports clear and maintain measurement accuracy over extended operating periods without manual intervention.
Specifications
- Multi-port averaging sensor for representative velocity measurement across the duct profile.
- Negligible pressure loss — suited to induced / forced draft and low-pressure systems.
- Retractable / hot-tap mounting options for installation without shutdown (application dependent).
- Temperature-compensated mass flow output when combined with temperature measurement.
Technical specifications.
| Parameter | Specification |
|---|---|
| Service | Flue gas, stack emissions, large ducts, CEMS |
| Duct/stack size | DN150 – DN6000 (6"–240") |
| Output | 4–20 mA with HART (multivariable optional) |
| Options | Auto-purge for dusty streams; hot-tap mounting |
| Metering principle | Differential pressure via multi-port averaging pitot tube |
| Application | Stack flue gas, flare stack, large-diameter duct flow, CEMS flow monitoring |
| Duct/stack size range | DN150 – DN6000 (6"–240"), customizable per application |
| Insertion type | Single-point insertion, spanning full duct/stack diameter |
| Process temperature | Up to 600°C (standard); higher on request with special alloys |
| Process pressure | Near-atmospheric to moderate positive/negative draft (application-specific) |
| Pitot tube material | SS316/316L (standard); SS310, Hastelloy, or other alloys for high-temperature/corrosive flue gas |
| Sensing ports | Multiple high-pressure (impact) and low-pressure (static) averaging ports along tube length |
| Mounting | Flanged / compression fitting, with hot-tap isolation valve option |
| DP/multivariable transmitter output | 4–20 mA with HART (Fieldbus/Profibus/Modbus optional) |
| Overall system accuracy | ±2% to ±5% of measured flow (typical; dependent on profile conditions and installation length) |
| Turndown ratio | Up to 4:1 |
| Auto-purge system | Optional; timer-based sequential purge with solenoid valves and regulator (air/N₂ supply required) |
| Purge media requirement | Instrument air or inert gas (application-dependent) |
| Hazardous area certification | ATEX / IECEx / CSA / FM (as required) |
| Enclosure protection | IP66 / IP67 |
Key features engineered in.
- True cross-sectional averaging — multi-port sensing captures a representative velocity profile, minimizing errors from flow profile distortion, swirl, or asymmetric duct flow
- Low permanent pressure loss — negligible impact on stack draft/ID fan performance compared to orifice or venturi-based technologies
- Application-specific material selection — resists corrosion, erosion, and high-temperature degradation typical of flue gas and stack environments
- Auto-purge capability — maintains accuracy in high-dust-loading applications (e.g., coal/biomass-fired boilers, cement kilns, incinerators) without frequent manual cleaning
- Hot-tap insertion/removal option — enables maintenance without process shutdown
- Wide application range — suitable for large-diameter stacks, ducts, and flue gas lines across power, cement, steel, and process industries
- CEMS-compatible — suitable for emissions monitoring and mass emission rate calculations
Applications we serve.
- Boiler flue gas / stack flow measurement (coal, biomass, oil, gas-fired)
- Cement kiln and process gas duct flow monitoring
- Incinerator and waste-to-energy stack flow measurement
- CEMS mass emission rate calculation (in combination with gas analyzers)
- Flare stack flow measurement
- Large-diameter HVAC and process ventilation duct flow monitoring
- ID fan / FD fan inlet-outlet flow verification
Need help with your flow measurement challenge?
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