Customer pain point
Low-velocity gas in a large duct can leave a conventional insertion probe with too little usable DP—or make a full-bore restriction impractical.
Custom low-loss measurement for large gas ducts
Double-Venturi Gas Flowmeters — Custom Large-Duct Gas Flow Meter
Application-engineered internal and insertion differential-pressure assemblies for low-velocity gas in large circular and rectangular ducts.
Rectangular-Duct Double-Venturi Flowmeter
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MANUFACTURER-SPECIFIC LARGE-DUCT METERING
Not a classical Venturi—engineered for low-velocity gas
The Shizhong Double-Venturi is a custom differential-pressure sensing assembly for large circular and rectangular gas ducts. It is selected when low gas density, weak signal, limited allowable pressure loss and retrofit access must be solved as one measurement-system problem.
Shizhong engineering response
Internal, insertion and integrated assemblies are configured around the actual section, process density, disturbance layout, access and maintenance plan.
Defensible performance
Coefficient, usable range, loss and uncertainty are stated from the approved geometry plus representative calibration or site correlation.
Configuration routes
Round or rectangular · internal or insertion
A factory-built measurement section controls supports and alignment. An insertion arrangement can reduce retrofit scope. Rectangular ducts require measured clear dimensions and a profile-validation plan.
Standards boundary
No transferred ISO 5167-4 coefficient
This device is not the classical Venturi tube defined by ISO 5167-4. ISO 3966, ISO 16911 and ISO 14164 may support reference measurement and validation where applicable; they do not assign one universal coefficient, accuracy or straight run to this product family.
Large-duct gas measurement engineered around the actual installation
Shizhong Double-Venturi Gas Flowmeters address large-duct duties where low gas density, low velocity, limited pressure-loss allowance and restricted retrofit access must be solved together. The manufacturer-specific sensing geometry produces a usable differential-pressure signal without the size and process penalty of a conventional full-bore restriction. Internal, insertion, integrated round-duct and rectangular-duct configurations are engineered around the actual process, duct, disturbance layout, maintenance plan and validation objective. This product is not the classical Venturi tube defined by ISO 5167-4; its coefficient and performance belong to the approved Shizhong geometry and project evidence basis.
Key design features
More usable differential-pressure signal for low-velocity gas
Low-loss internal or insertion configurations for large ducts
Round and rectangular duct engineering
Project-specific calibration, velocity-area comparison or site correlation
Related Solutions
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Typical applications
01
Blast-furnace, coke-oven, converter and mixed-gas ducts
02
Boiler primary air, secondary air and combustion air
03
Flue gas and large process-exhaust ducts
04
Low-pressure, low-velocity industrial gas measurement
Final specifications are confirmed against process data, piping, material, pressure class, applicable code and metrology requirements.
ENGINEERING ANSWER UNITS
Application boundaries, selection and troubleshooting
These product-specific answers retain the source evidence, calibration limits and conditions where a different measurement route is preferable. Values that cannot be confirmed from the approved source remain subject to project review or pending field test; no unverified value is supplied here.
Machine-readable answer infrastructure: the same visible question and answer text is published as FAQPage JSON-LD to support page understanding and AI retrieval. Google discontinued FAQ rich results on 07 May 2026, so no rich-result display is promised.
Dataset v1.5.0; last reviewed 2026-08-24. Evidence IDs are retained in the translation dataset.
How does a Double-Venturi differ from other flow-measurement devices, and when can it replace them?
Replacement: For large-duct, low-velocity gas measurement, a Double-Venturi can be an alternative to a large-bore orifice or an airfoil-type velocity measurement route. Use it when: The service is low-density, low-velocity gas in a large duct, such as blast-furnace, coke-oven or converter gas or boiler air, and low loss plus stronger differential-pressure signal are important. Do not force the substitution when: Small lines, liquids or steam do not follow this gas-specific device route. High-accuracy custody measurement still requires representative calibration or an approved site comparison.
COMPARISON REPLACEMENT · MEDIUM source confidence
When is a Double-Venturi recommended, and when should another measurement route be compared?
Recommended application: Use a Double-Venturi for low-velocity industrial gas in large circular or rectangular ducts, including blast-furnace, coke-oven and converter gas, when each supplied device can receive flow calibration or an approved site comparison. Prefer another route when: The line is small, the fluid is liquid or steam, or the project requires standardized geometry with direct use of a standard uncertainty. Compare an orifice plate, classical Venturi or another applicable route. Standards boundary: The Double-Venturi is manufacturer-specific and is not an ISO 5167-4 classical Venturi. ISO 3966:2025, ISO 16911-1/-2 and ISO 14164 may be used as reference measurement or validation methods, subject to the approved calibration or site-comparison basis.
RECOMMENDATION COMPARISON · HIGH source confidence
What temperature and pressure can a Double-Venturi handle?
Typical temperature is below 400℃; higher temperature requires a review of materials, supports and instrumentation. The typical series is available up to PN6.4 MPa; the final limit follows the mechanical design and project specification. Temperature and pressure must be assessed together during project design.
TEMPERATURE PRESSURE · MEDIUM source confidence
What pipe and duct sizes are available for a Double-Venturi?
Circular pipe: DN500—DN4000. Rectangular duct: typically 600 × 600～3600 × 3600 mm. Final supplied dimensions are project-specific and must account for the section, supports, velocity distribution and installation conditions.
DIAMETER RANGE · HIGH source confidence
Which materials are available for a Double-Venturi?
Stainless steel, carbon steel, Hastelloy and other project-approved alloys are available. Final material selection must account for corrosion, the temperature-pressure combination, support structure and project mechanical design.
MATERIALS LINING · MEDIUM source confidence
How is a Double-Venturi calibrated, and how are accuracy and turndown confirmed?
This is a manufacturer-specific device, not an ISO 5167-4 classical Venturi. ISO 3966, ISO 16911 and ISO 14164 may support project reference measurement or validation, together with representative calibration and site comparison. Accuracy: ±0.5% after individual flow calibration, stated only as covered by the certificate. Turndown depends on the lowest usable differential pressure, gas density, transmitter rangeability and verified operating range; a no-calibration claim for standardized geometry does not apply.
CALIBRATION ACCURACY · MEDIUM source confidence
What should be checked when a Double-Venturi fluctuates, is biased, or produces no differential-pressure signal?
Symptom: Differential pressure fluctuates, the reading is biased, or there is no signal. Possible causes: A blocked or leaking pressure tap or impulse line, trapped liquid or gas, deposits or damage in the measurement section, an inlet profile outside the approved conditions, or a transmitter or manifold fault. Action: Check the power supply, manifold and impulse system first, and vent gas or drain liquid as appropriate. Then compare the installation with the approved data; after isolation and depressurization, inspect the measurement section and clean, repair and site-compare it if required.
TROUBLESHOOTING · MEDIUM source confidence
Related products
Full-Section Matrix FlowmetersA patented multi-point differential-pressure array engineered for large circular pipes, rectangular ducts and gas-flow profiles that a single-point or single-bar probe may not represent.Lierba & Averaging Pitot FlowmetersShizhong Lierba™ combines a low-loss insertion probe with a proprietary anti-plugging pressure-opening concept, drainage-friendly geometry and engineered purge or online-service options for large pipes and difficult gases.
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