WU Series Gas Ultrasonic Flowmeter

1. Overview

The WU series gas ultrasonic flow meter is manufactured using advanced German technology, with key components sourced as genuine imported parts. It features high reliability, stable performance, and a long service life, making it a new type of high-precision and highly reliable precision metering instrument. It is widely applicable for gas flow measurement in industries such as city gas, petroleum, chemical, power, and metallurgy.

The WU series gas ultrasonic flow meter adopts a multi-channel design, which compensates for the effects of vortices and asymmetric flow. The multiple channels include redundant backup channels, enhancing system reliability. It complies with international standards including ISO 17089, the American standard A.G.A. Report No. 9, as well as Chinese standards GB/T 34041.1-2017 and GB/T 18604-2014.

The product meets the requirements of GB/T3836.1 - 2021 "Explosive Atmospheres — Part1: General Requirements for Equipment" and GB/T 3836.4-2021 "Explosive Atmospheres — Part4: Equipment Protected by Intrinsic Safety 'i'". It carries the explosion-proof marking Ex ib IIB T4 Gb and is suitable for use in Zone 0, Zone 1, or Zone 2 environments where explosive mixtures formed by Group IIB, T1 to T4 flammable gases or vapors and air are present.

2. Key Features

• Manufactured with advanced German technology, delivering excellent product performance.

• Multi-channel measurement with eddy current and asymmetric flow detection ensures measurement accuracy.

• Built-in flow conditioning reduces installation requirements, allowing direct replacement of turbine or rotary meters.

• Layered shielding against electric and magnetic fields provides high noise immunity.  

• Automatic zero-drift correction maintains accuracy unaffected by environmental changes.  

• Measurement accuracy class: Optional 1.0 or 1.5 grade.  

• Ultra-wide measurement range of 1:700, suitable for metering in scenarios with significant peak-valley fluctuations.

• Ultra-low "zero" start flow, with up to 50% Q_max overload capability while remaining within accuracy specifications.

• No moving parts, supports both horizontal and vertical installation.  

• Dual backup lithium battery power supply ensures over five years of battery life.  

• High-precision temperature and pressure compensation with volume correction.  

• Intelligent switching between various gas operating conditions and standard conditions.  

• Large-capacity storage for up to one year of data retention.  

• Intelligent fault detection and alarm for immediate identification of instrument issues.  Maintenance-free, easy to clean, and long service life.  

• Optional built-in IoT module for remote data monitoring.

3. Working Principle

3.1 Working Principle of Gas Ultrasonic Flow Meter

Gas ultrasonic flow meter operate on the principle of measuring the relationship between the time of sound wave propagation in a flowing medium and the flow rate. It is generally recognized that the actual propagation velocity of sound waves in a fluid consists of the speed of sound in the stationary medium (C_f) and the component of the axial average flow velocity (V_m) of the fluid along the direction of sound wave propagation. As illustrated in the diagram, the relationship between downstream and upstream propagation times and the relevant variables is as follows:

Using formula (1), the expression for fluid flow velocity can be obtained.

The measured fluid velocities V_i (i=1, 2, … k) from multiple acoustic paths are combined using a mathematical functional relationship to obtain the estimated mean velocity of the pipeline. Multiplying by the cross-sectional area A yields the volumetric flow rate q_v, as shown in Equation (3):

3.2 Multi-Path Gas Ultrasonic Flow Meter

The multi-path gas ultrasonic flow meter adopts a multi-channel design, featuring high noise immunity, the ability to detect vortices and asymmetric flows, elimination of uncertain inherent delays in sensors and processing circuits, and high measurement accuracy. Additionally, the multi-path configuration serves as a redundancy backup, ensuring that the WU series gas ultrasonic flow meter continues to operate reliably even if individual sensors are damaged, significantly enhancing detection reliability.

FIG.2  Multi-path Configuration Diagram (Type B: DN25-DN100 with Dual-path; Type A: DN80-DN250 with Quad-path)

3.3 Working Principle of the Volume Corrector

The volume corrector consists of digital channels for temperature and pressure detection, a flow detection digital channel, a microprocessing unit, an LCD drive circuit, and other auxiliary circuits. It is also equipped with external signal output interfaces. Its working principle is illustrated in FIG.2. Input signals from various sensors are converted and processed, after which the microprocessor performs calculations using the gas state equation. This enables local display and the transmission of multiple signals over long distances. The gas law can be expressed as:

FIG.3 Volume Corrector Functional Block Diagram

4. Technical Specifications

4.1 Applicable Standards

1. WU Series Gas Ultrasonic Flow Meters comply with the verification regulation JJG1030-2007 "Ultrasonic Flow Meters".

2. The product also conforms to the enterprise standard Q/WD011-2022 "Gas Ultrasonic Flow Meters".

4.2 Accuracy Class

1. Accuracy Class within the Measuring Range: Class 1.0 and Class 1.5.

   Class 1.0: 0.2Q_max ~ Q_max: ±1.0%; Q_min ~ 0.2Q_max: ±2.0%.

   Class 1.5: 0.2Q_max ~ Q_max: ±1.5%; Q_min ~ 0.2Q_max: ±3.0%.

2. Temperature Display Error: ≤±0.5°C

3. Pressure Display Error: ≤±0.2% (≥20% of P_max). (The upper range limit (P_max) of the pressure sensor is available in the following options: 0.2, 0.5, 1.0, 5.0, 10 MPa (absolute)).

4.3 Electrical Specifications of the Volume Corrector

4.3.1 Power Supply:

• Internal Power Source: 3.6 V DC lithium battery. The screen displays the battery icon 1 with a real-time capacity percentage (trend value) to prompt the user for battery replacement.

• External Power Source: (9 to 28) V DC, ripple ≤50 mV. When the external power source is connected, the internal power source is automatically disconnected, and the unit operates on external power.

• (Optional) Built-in EVE Dedicated Battery: 3.6 V DC battery, exclusively powering the GPRS communication module. The screen displays the battery icon 2 with a real-time capacity percentage (trend value) to prompt the user for battery replacement.

4.3.2 Overall Power Consumption:

• Internal Power Source: Average power consumption ≤0.8 mW. A single #2 lithium battery can provide continuous operation for over three years. In dormancy state, power consumption ≤0.2mW.

• External Power Source: Overall power consumption ≤1 W.

• EVE Dedicated Power Source: In dormancy state, power consumption ≤0.05 mW.

4.3.3 Input Signals:

• Flow Signal: (0 ~ 5) kHz pulse signal, V_pp = 3.0 V.

• Temperature Signal: Resistance signal output by the temperature sensor.

• Pressure Signal: Digital signal output by the pressure sensor.

4.3.4 Output Signals:

• Pulse Signal (Three-Wire System): Directly outputs the operating condition pulse signal detected by the flow sensor after optocoupler isolation and amplification. Maximum amplitude is approximately (V_ext-2) V (where V_ext is an external power supply of 9 ~ 28 V DC). Transmission distance is ≤50 m. Powered by the external supply.

• (4 ~ 20) mA Standard Analog Signal: The (4 ~ 20) mA signal linearly corresponds to the (0 ~ Q_max) m³/h standard volumetric flow rate (default Q_max = 2000 m³/h, adjustable via internal parameters). Transmission distance ≤200 m. Wiring can be two-wire or three-wire system. Powered by +24 V DC external supply.

• Standard Flow Signal: Outputs as a pulse train. Normal state is low level (≤0.2V). High level amplitude is ≥2.8 V. Transmission distance ≤20 m. Volume per pulse is configurable: 0.1 m³/1 m³/10 m³. Pulse width is configurable: 5 ms/50 ms/500 ms. Suitable for use with IC card systems.

• Control Signal Outputs:

1. Low Battery Alarm (BJ, GND): CMOS level output. Default is low level (configurable). The BJ terminal outputs an alarm signal when battery voltage falls below 3.2 V. For use with IC card controllers.

2. Upper/Lower Limit Alarm (H/L, GND): CMOS level output. Default is high level (configurable). The H/L terminal outputs an alarm signal when the operating flow rate exceeds the upper alarm limit or falls below the lower alarm limit.

• RS-485 Interface Signal: Uses MODBUS protocol in RTU mode, half-duplex. Configurable baud rate from 9600 to 38400. Enables direct networking with host computers for remote transmission of measured medium temperature, pressure, instantaneous flow rate, total standard volume, relevant instrument parameters, fault codes, operational status, and real-time data.

• Real-Time Database: To meet data management needs, the instrument features real-time datastorage, including:

◆ 3 Months of Hourly Records (2160 entries): One record logged at the 00 second of each hour.

◆ 3 Years of Daily Records (1095 entries): One record logged at 00:00:00 each day.

◆ 10 Years of Monthly Records (120 entries): One record logged at 00:00:00 on the 1st of each month.

The stored data can be retrieved via the RS-485 interface using a laptop or desktop computer to generate data tables and curve graphs for analysis as required by the user.

4.3.5 Wireless Communication (Optional):

A built-in wireless remote transmission module is available. When powered by a lithium battery, it can periodically or at scheduled times upload the working mode; with one daily transmission on average, the battery can last over three years. The module transmits current operating data to the cloud via corresponding wireless methods. Users can view the calibrator's operational data and fault events through websites, software, or WeChat mini-programs.

4.4 Mechanical Performance Specifications  

The flow meter models and basic parameters are listed in Table 1.  

Table 1  Model Specifications and Parameters

Note: 

① The flow range listed in the table refers to the flow range during factory calibration of the product (with air as the medium under normal temperature and pressure);

② The flow range expands as the pressure increases.

4.5 Explosion-proof marking: Intrinsically safe Ex ib IIC T4 Gb  

4.6 Protection rating: IP65

5. Dimensions and Installation

The external dimensions of the flow meter are shown in FIG.4. Undimensioned details are listed in Table 2. The flow meter adopts a flange connection, with flange dimensions complying with the GB/T 9124-2019 standard.

FIG.4  Flow Meter Dimensional Drawing

Unit: mm                                                                                                        Table 2

6. Dimensions and Installation

• When ordering this product, users shall select the appropriate specification based on the pipeline nominal pressure, maximum medium pressure, medium temperature, flow range, and environmental conditions. Additionally, the suitable electronic register shall be chosen according to actual requirements.

• When placing an order, users are requested to correctly fill in the information according to the following format.