CUBIC INSTRUMENTS BF-2000 Ultrasonic Biogas Flow Meter

Overview

The CUBIC INSTRUMENTS BF-2000 is a purpose-engineered ultrasonic biogas flow meter designed for continuous, non-intrusive measurement of volumetric flow rate and methane (CH₄) concentration in low-pressure biogas streams. Based on time-of-flight (TOF) ultrasonic transit-time differential principle, the BF-2000 eliminates mechanical moving parts—such as diaphragms or turbines—thereby ensuring long-term metrological stability under variable gas composition and moisture-laden conditions common in anaerobic digestion environments. Unlike thermal or differential pressure-based meters, this device delivers simultaneous, real-time quantification of both flow and CH₄ content without requiring external gas analyzers or calibration gases. Its design conforms to fundamental metrological requirements outlined in OIML R137 (gas meters) and supports traceable compliance with national biogas subsidy verification protocols where CH₄ purity reporting is mandated.

Key Features

• Integrated dual-parameter measurement: Simultaneous determination of volumetric flow (Nm³/h) and CH₄ mole fraction (%), enabling accurate energy-content-based billing and policy-compliant reporting.
• Ceramic ultrasonic transducers: Specially formulated piezoelectric ceramic elements resist chemical degradation from hydrogen sulfide (H₂S) and condensate exposure—critical for long-term reliability in untreated or minimally scrubbed biogas.
• Diaphragm-free architecture: No elastomeric membranes or sliding seals; capable of withstanding transient pressure surges up to 20 kPa without drift or mechanical fatigue.
• Embedded temperature compensation: Integrated Pt1000-grade thermistor enables real-time thermal correction of speed-of-sound calculations, minimizing density-related errors across the full operating range (−10 to +40 °C).
• IC-card-based prepayment interface: Supports secure, tamper-resistant gas consumption accounting with automatic valve shutoff upon credit depletion—compliant with rural energy management frameworks.
• Intrinsically safe electronics: Certified to Ex ib IIB T3 Gb per EN 60079-0 and EN 60079-11, suitable for installation in Zone 1 hazardous areas adjacent to digesters, storage tanks, or flare lines.

Sample Compatibility & Compliance

The BF-2000 is validated for use with raw, conditioned, and upgraded biogas containing variable concentrations of CH₄ (30–100 %), CO₂ (0–70 %), H₂S (≤500 ppm), water vapor (saturated at operating temperature), and trace contaminants (NH₃, siloxanes). It meets the mechanical and environmental robustness criteria specified in GB/T 6968–2019 (Chinese standard for domestic gas meters) and aligns with functional safety expectations for Class B devices under IEC 61508. While not certified to MID (Measuring Instruments Directive) or ANSI Z21.13, its metrological performance satisfies technical prerequisites for inclusion in government-subsidized biogas utilization projects requiring auditable CH₄ reporting—particularly under national renewable energy incentive schemes mandating minimum 55 % CH₄ thresholds for feed-in tariff eligibility.

Software & Data Management

The BF-2000 operates autonomously with local data logging (up to 12 months of hourly flow and CH₄ records stored in non-volatile memory) and supports periodic data retrieval via infrared (IR) optical interface using proprietary configuration software. Logged data includes timestamped flow totals, CH₄ concentration averages, battery voltage status, and diagnostic flags (e.g., signal-to-noise ratio degradation, transducer coupling loss). All stored values are write-protected and retain integrity during power interruption. The firmware implements basic audit-trail functionality—including parameter change timestamps and user access logs—supporting GLP-aligned recordkeeping for third-party verification. No cloud connectivity or remote telemetry is embedded; data export is restricted to offline IR transfer to prevent unauthorized network exposure in distributed rural installations.

Applications

Primary deployment contexts include household-scale biogas systems serving individual farms or clustered rural dwellings; livestock manure digesters operated by commercial piggeries or dairy cooperatives; agricultural co-digestion plants processing crop residues and food waste; landfill gas extraction and flaring stations; and EPC contractors installing turnkey biogas upgrading and utilization infrastructure. The BF-2000 serves as both a fiscal meter for utility-style billing and a verification instrument for regulatory reporting—especially where subsidy disbursement hinges on demonstrated CH₄ yield rather than gross volume. Its compact form factor (G2.5 class) and battery-powered operation make it ideal for off-grid, low-infrastructure sites lacking stable AC supply or communication infrastructure.

FAQ

Does the BF-2000 require periodic recalibration?
No scheduled recalibration is required under normal operating conditions. The ultrasonic time-of-flight method is inherently stable; verification may be performed annually using reference flow benches per GB/T 6968–2019 Annex F.
Can it measure biogas containing >500 ppm H₂S?
Operation above 500 ppm H₂S is not recommended without upstream desulfurization; prolonged exposure may accelerate ceramic transducer aging beyond warranty terms.
Is the IC-card interface compatible with international prepayment standards?
The interface adheres to ISO/IEC 7816–3 physical layer specifications but uses a proprietary application protocol; integration with regional utility platforms requires middleware adaptation.
What happens when battery voltage drops below operational threshold?
The LCD displays a low-battery warning 30 days prior to cutoff; all metering functions remain active until voltage falls below 3.0 V, after which the valve closes and logging ceases.
How is CH₄ concentration determined without gas chromatography?
CH₄ fraction is inferred from the empirically calibrated relationship between ultrasonic sound velocity, gas temperature, and known binary mixture behavior (CH₄/CO₂/H₂O), validated against reference gas standards across the 30–100 % range.