overview

It is recommended to use a gas vortex flowmeter (also known as a vortex flowmeter) for measuring compressed air and other gases. It is an extremely versatile flow measuring instrument that can be used for almost all gas measurements and controls.

Stress type gas vortex flowmeter is a type of velocity flowmeter, which is based on the Karman vortex theory and uses piezoelectric crystals to detect the vortex frequency generated when the fluid passes through the triangular column in the pipeline, thereby measuring the flow rate of the fluid.

Technical Parameter

Nominal diameter:

Flange type: DN15-DN300、 Insertion type: DN200-DN2000

Scope of application: Compressed air, carbon dioxide, oxygen, nitrogen and other gases

Medium temperature: - 40℃-150℃

Nominal pressure: ≤ 1.6MPa, ≤ 2.5MPa, ≤ 4MPa, ≤ 6.3MPa

Accuracy level: flange type 1.5 level, plug-in type 2.5 level

Flow velocity range: 3-70m/s

Measurement range: see Table 1

Output signal: 4-20mA current RS485

Power supply: AC220V/DC24V/DC24V+3.6V lithium battery/3.6V lithium battery

Environmental temperature: - 20℃-+55℃

Relative humidity: 5% -90%

Table body material: 304 stainless steel

Protection level: IP65、IP67

Selection of gas vortex flowmeter

The preferred method for measuring gases is to use a split temperature and pressure compensated gas vortex flowmeter, which includes a vortex flow sensor, an intelligent flow integrator, a pressure transmitter, a Pt-100 platinum thermistor, and a wall mounted instrument box. This configuration is metrological and displays volumetric flow rates under standard and operating conditions, as shown in Figure 2; An integrated temperature and pressure compensation gas vortex flowmeter can also be used, which displays the volumetric flow rate under standard and operating conditions, as shown in Figure 3; Sometimes, when measuring gases, an integrated vortex flowmeter without compensation is also used to display the volumetric flow rate under operating conditions. This configuration can meet the measurement of the volumetric flow rate under operating conditions. If the volumetric flow rate under standard conditions is to be displayed, this configuration is not scientifically calibrated.

Figure 2: Split type vortex flowmeter with temperature and pressure compensation

Figure Three Integrated Temperature and Pressure Compensation Gas Vortex Flow Meter Figure Four Integrated Non Compensation Gas Vortex Flow Meter

It is also necessary to determine whether the vortex flowmeter has the following functions

1. Need to provide PLC DCS、 If input signals are provided by calculators, digital displays, etc., 4-20mA current output is required;

2. To collect data on temperature, pressure, and flow meters, an RS485/RS232 communication interface is required;

3. Is it necessary to equip a wall mounted instrument box for fixing and protecting the intelligent accumulator;

4. Is it necessary to equip a backup power supply to ensure that the entire measurement system can work normally for more than 100 hours during a power outage;

5. Is remote meter reading necessary to achieve real-time monitoring of parameters such as flow rate, temperature, and pressure.

Finally, it is necessary to determine the diameter of the flowmeter - a flow based diameter selection method

1. The measuring range of a flowmeter varies depending on its nominal diameter, and the measuring range of each diameter also changes with the temperature and pressure of the gas.

2. When selecting a flow meter diameter, one should not directly choose a flow meter of the same diameter as the pipeline diameter, but should match the actual instantaneous flow rate with the flow range of that diameter.

3. The selection of a suitable diameter for a flowmeter is to address the current measurement needs, while also considering the possibility of increased flow in the future when the flow rate is appropriate; Instead of the opposite, only consider the possibility of increased traffic in the future, ignoring the possibility of smaller traffic now.

4. To determine the approximate operating flow range of the gas, the nominal diameter of the flowmeter can be determined by using the table lookup method (Table 1).

Selection of Typical Temperature and Pressure Compensation Gas Vortex Flow Meter

Example 1: The tested medium is compressed air with a gauge pressure of 0.2MPa and a temperature of 60 ℃. The process requires a gas consumption of 300Nm3/h-1500Nm3/h, equipped with an accumulator (with RS485 interface), pressure transmitter, Pt-100 platinum resistor, instrument box, and instrument diameter and model selection.

Solution: According to the gauge pressure of 0.2MPa, temperature of 60 ℃, and process gas consumption of 300-1500Nm3/h, the operating flow range of the gas is calculated to be 123-618m3/h according to the "LUGB Series Vortex Flow Meter Selection and Use Manual". At the same time, according to Table 2 of the selection and use manual, the standard range of the DN80 vortex flow meter is 70-700m3/h, which meets the requirements of the flow rate. Therefore, the nominal diameter of the instrument is selected as DN80.

DN80 Vortex Flow Meter Model: LUGB-+1DRM0P1T1

Typical Integrated Gas Vortex Flow Meter Configuration and Selection

Example 2: The measured medium is nitrogen gas, with a gauge pressure of 0.6MPa and a temperature of 20 ℃. The process requires a flow rate of 30m3/h-150m3/h, displaying only the operating flow rate. An integrated meter head display is used, with an output of 4-20mA. The instrument diameter and model are selected.

Solution: According to the measured medium nitrogen, the process requires a flow rate of 30m3/h-150m3/h. According to Table 1 of the "LUGB Series Vortex Flow Meter Selection and Use Manual", the standard range of DN40 vortex flow meter is 25-200m3/h. Therefore, the nominal diameter of the instrument is selected as DN40.

DN40 Vortex Flow Meter Model: LUGB-C01

In the above example, only the operating flow rate is displayed, using an integrated meter head display, without requiring signal output, and selecting the instrument diameter and model.

DN40 Vortex Flow Meter Model: LUGB-C01

In the above example, only the standard condition and operating flow rate are displayed, using an integrated header display without requiring signal output. The instrument diameter and model are selected.

DN40 Vortex Flow Meter Model: LUGB-D01