Gas vortex flowmeter

Gas vortex flowmeterSelection and Installation Guide

1、 Core elements of selection

Matching of medium characteristics

Applicable MediumGases (such as air, natural gas, steam, etc.) need to have their composition, density, viscosity, and conductivity clearly defined.

Taboo mediumHigh viscosity fluids (such as heavy oil), fluids containing a large amount of particles/suspended solids, and gases that are prone to crystallization or corrosion (requiring special materials).

Steam typeDistinguish between saturated steam and superheated steam, the latter requiring temperature and pressure compensation to accurately measure mass flow rate.

Flow range to range ratio

Determine the minimum, common, and maximum flow rates, and select instruments with sufficient range ratio (maximum/minimum flow rate) (usually 7:1-10:1).

key pointsAt the minimum flow rate, the Reynolds number should be greater than 20000 to avoid unstable signals caused by low flow rates.

Accuracy and repeatability

Select the accuracy level according to the requirements (such as ± 1%, ± 1.5%), and the gas measurement usually has an accuracy of level 1.5.

When high repeatability is required, priority should be given to models with strong anti vibration performance (such as differential sensor design).

Temperature and pressure tolerance

temperature rangeThe conventional type can reach -40 ℃~100 ℃, while the high-temperature type can reach 350 ℃ (requires a radiator).

pressure ratingSelect the nominal pressure (such as 1.0MPa, 2.5MPa) according to the operating conditions to ensure compatibility with the pipeline.

Output signal and communication

analog output4-20mA (suitable for remote signal transmission).

digital outputPulse/frequency, HART, Modbus RS485 (for easy integration into automation systems).

Temperature and pressure compensation demandGas measurement requires simultaneous compensation for temperature and pressure, and an integrated or external transmitter model should be selected.

Installation environment adaptability

protection levelIP65 (indoor), IP67/IP68 (outdoor or humid environment).

Explosion-proof requirementsFlammable and explosive locations require Ex ia/IC T6 Ga or Ex d IIC T6 Gb certification.

Anti vibration designEvaluate the strength of pipeline vibration sources, select anti vibration types or install shock absorbers.

2、 Key installation steps and precautions

Installation location selection

Horizontal pipelineRecommended installation: If gas measurement contains a small amount of liquid, it should be installed at a higher position in the pipeline.

Vertical pipelineGas can flow from top to bottom or from bottom to top, while liquid must flow from bottom to top to avoid bubble accumulation.

Avoid interference sourcesKeep away from vibration sources such as pumps and compressors (with a spacing of ≥ 5 times the pipe diameter), and avoid strong electromagnetic fields (such as frequency converters).

Requirements for straight pipe sections

Upstream straight pipe sectionUsually requires 15-20 times the pipe diameter. If there is a reduction, expansion, bend or valve, it needs to be extended to 30-50 times the pipe diameter.

Downstream straight pipe sectionAt least 5 times the pipe diameter, it is recommended to reserve 50 times the pipe diameter after the pump or regulating valve.

rectifierWhen space is insufficient, installation can be considered.

Pipeline and flange installation

concentricityThe flowmeter and pipeline flange need to be strictly aligned. Eccentricity or gasket intrusion into the inner wall of the pipeline will affect the measurement.

Support and reinforcementWhen the diameter of the pipeline is ≥ DN200, a support bracket needs to be installed to prevent pipeline stress from being transmitted to the flowmeter.

Variable diameter processingIf the size of the pipeline is not consistent with the diameter of the flow meter, a transition should be made through a tapered/expanding pipe (cone angle ≤ 15 °).

Electrical connection and grounding

signal cableUse shielded twisted pair cables, with the shielding layer grounded at one end (usually at the display instrument end), to avoid parallel laying with power cables (spacing ≥ 0.5 meters).

grounding resistancePipeline grounding resistance ≤ 10 Ω, it is recommended to install isolation transformers in strong interference environments.

Power isolationEnsure stable power supply voltage and avoid voltage fluctuations that may damage electronic components

Environmental protection measures

high-temperature protectionWhen measuring high-temperature media, the flowmeter converter should avoid direct exposure to high-temperature environments (such as when the converter is located on the side of the pipeline when installed horizontally).

Moisture proof and sun protectionInstall a sunshade when installing outdoors to avoid direct sunlight; Seal the cable entrance with waterproof tape.

hygiene requirementsThe food and beverage, pharmaceutical industries need to choose hygienic connections (such as card discs, three clamps) and easy to clean designs.

IIIGas vortex flowmeterCommon Problems and Solutions

Large measurement error

reasonInsufficient straight pipe section, protruding sealing gasket into the pipeline, two-phase flow (such as gas containing liquid droplets).

solveAdjust the length of the straight pipe section, replace the sealing gasket, and ensure that the medium is a uniform single-phase flow.

No signal output or no display of instantaneous flow rate

reasonCircuit wiring error, abnormal power supply voltage, sensor damage.

solveCheck the wiring and power supply, measure the sensor resistance (should be>2M Ω), and replace the faulty component.

Unstable signal output

reasonThe medium flow rate exceeds the range, the pipeline vibration is too large, and there is electromagnetic interference.

solveAdjust the flow range, install shock absorbers or hose transitions, strengthen shielding and grounding.

Leakage of measuring tube

reasonHigh pressure inside the pipe, incorrect selection of nominal pressure, sensor corrosion.

solveReduce pressure, use sensors with higher nominal pressure, and take anti-corrosion measures

Note: 1. The prices on the system are only reference prices and not actual prices;

2. Flow meters vary in specifications, diameters, and configurations, resulting in different prices. We need to select and quote based on your operating conditions~

After sales and warranty

All products supplied by Duoqin Instrument (Shanghai) Co., Ltd.:

All products come with a 2-year warranty;

Provide free telephone consultation, guidance on installation and debugging services;

Negotiate on-site guidance for installation, debugging, and other matters, and only charge reasonable travel expenses;

Large quantities can provide free on-site guidance for installation and debugging.