Intelligent flange type vortex flowmeter

·Capable of measuring the volumetric and mass flow rates of steam, gas, and liquid
·No mechanical moving parts, high measurement accuracy, compact structure, easy maintenance
·Low pressure loss and wide range of measurement
·The instrument adopts anti-interference circuit and anti vibration sensing head, which has
Anti environmental vibration performance
·The measurable medium temperature reaches+350 ℃ (+450 ℃)
1、 Overview
The LUGB vortex flowmeter is a volumetric flowmeter that measures the volumetric flow rate, standard condition volumetric flow rate, or mass flow rate of gases, vapors, or liquids based on the Karman vortex principle. And it can be used as a flow transmitter in automation control systems.
This instrument adopts advanced differential technology, combined with isolation, shielding, filtering and other measures, to overcome the problems of poor seismic resistance and small signal data disorder of similar products. It also adopts unique sensor packaging technology and protective measures to ensure the reliability of the product. The product comes in two forms: basic type and composite type. The basic type measures a single flow signal; The composite type can simultaneously measure temperature, pressure, and flow rate. Each form has a whole or separate structure to adapt to different installation environments.
2、 Working principle
A vortex flowmeter is composed of a vortex generator designed in the flow field, a detection probe, and corresponding electronic circuits. When the fluid flows through a vortex generator, two alternating rows of vortices are formed on both sides, which are called Karman vortex streets. Based on the theory of Karman vortex street, Strohal proposed that the frequency of Karman vortex street is proportional to the flow velocity of the fluid, and gave the relationship between frequency and flow velocity:
f = St × V/d 式中:
Frequency of vortex street occurrence (Hz)
Average velocity on both sides of the vortex generator (m/s)
St Strohal coefficient (constant)
These alternating vortices form a series of alternating negative pressures, which act on the detection probe to generate a series of alternating electrical signals. After conversion, shaping, and amplification by a preamplifier, the output is a pulse frequency signal (or standard signal) proportional to the synchronization with the vortices.
3、 Characteristics and Applications of Instruments
Features:
·No movable parts, long-term stability, simple structure for easy installation and maintenance;
·Adopting anti-interference circuit and anti vibration sensing head, it has certain anti environmental vibration performance;
·Adopting ultra-low power single-chip microcomputer technology, one 3.2V10AH lithium battery can be used for more than 5 years;
·Correction of instrument coefficient nonlinearity by software to improve measurement accuracy;
·Low pressure loss and wide range of measurement;
·Using EEPROM for power down protection of accumulated traffic, with a protection time greater than 10 years;
Instrument Classification
1. Vortex flowmeters can be divided into two categories based on their instrument structure, namely:
Full tube vortex flowmeter
Widely used for measuring the flow rates of various medium and small-sized pipelines for water supply and drainage, industrial circulation, sewage treatment, oil and chemical reagents, as well as compressed air, saturated and superheated steam, natural gas, and various media.
Plug in vortex flowmeter
Widely applicable to large-diameter gas, liquid, and steam flow measurement in various industries, it can also measure turbid liquids containing small particles and impurities, and can be used as a flow transmitter in automatic control systems

Main technical indicators
Table 1

Instrument selection
A. The applicable flow range for general liquids and gases is shown in Table 2
Table 2
Flow range of full tube vortex flowmeter

Flow range of plug-in vortex flowmeter

The frequencies in the table are theoretical values. The testing conditions for the flow rate range of liquid usage are constant warm water (t=20 ℃, ρ=1000Kg/m3）。 The testing conditions for measuring the range of gas usage are air at room temperature and pressure (t=20 ℃, P=101.325Kpa，ρ=1.205 Kg/m3）
B. Convert the volumetric flow rate under known standard conditions to the volumetric flow rate under operating conditions
The commonly used unit of measurement for general gases is the standard state volume unit, which is the standard cubic meter per hour (Nm3/h), abbreviated as "standard square". Convert the standard volumetric flow rate to the operating volumetric flow rate in cubic meters per hour (m3/h) using the following formula, and then compare it with the applicable flow range in Table 2.

In the formula: Q represents the volumetric flow rate of the measured medium under operating conditions. （m3/h）
Q standard: Volume flow rate of the measured medium under standard conditions. (Nm3/h, 20 ℃, 0.1013MPa absolute pressure)
T-mark: The temperature of the measured medium under operating conditions. (293.15K)
P worker: The medium pressure and gauge pressure under the working condition of the measured medium. (MPa)
C. For saturated steam, it can be selected by comparing the range of mass flow rates given in Table 3.
D. For superheated steam, the density values at the corresponding temperature and pressure (absolute pressure: gauge pressure+1) should be checked against the superheated steam table (Table 4) first. Then, based on the given mass flow rate, the corresponding volume flow rate should be calculated using the following formula, and compared with the gas flow rate of the corresponding caliber in Table 2 for selection.

Flow range of saturated steam
Table 3