Selection of nitrogen precision flowmeter

Selection of nitrogen precision flowmeter-Jiangsu Dingsheng Instrument Co., Ltd

1、 Product performance of nitrogen precision flowmeter:

The DS-WLUGB series intelligent vortex flowmeter is mainly used for flow measurement of industrial pipeline media fluids, such as gases, liquids, vapors, and other media. Its characteristics are small pressure loss, large range, high accuracy, and almost unaffected by parameters such as fluid density, pressure, temperature, viscosity, etc. when measuring volumetric flow rate under working conditions. No movable mechanical parts, therefore high reliability and low maintenance. The instrument parameters can remain stable for a long time. This instrument adopts a piezoelectric stress sensor with high reliability. It has both analog standard signals and digital pulse signal outputs, making it easy to use in conjunction with digital systems such as computers. It is an ideal flow meter.

2、 Measurement principle of nitrogen precision flowmeter:

When a triangular cylindrical vortex generator is set up in the fluid, regular vortices are alternately generated from both sides of the vortex generator, which are called Karman vortices. As shown in the figure on the right, the vortex columns are asymmetrically arranged downstream of the vortex generator.

Assuming the frequency of vortex occurrence is f, the average flow velocity of the measured medium is, the width of the upstream surface of the vortex generator is d, and the diameter of the body is D, the following relationship can be obtained: f=SrU₁/d=SrU/md

In the formula, U1 represents the average velocity on both sides of the vortex generator, m/s；
Sr Strouhal number;
M - The ratio of the bow shaped area on both sides of the vortex generator to the cross-sectional area of the pipeline
The volumetric flow rate qv inside the pipeline is

qv=πD²U/4=πD²mdf/4Sr

K=f/qv=[πD²md/4Sr]^-1 　　　　　　　　　　　　　　　　

In the formula, K - the instrument coefficient of the flowmeter, pulse count/m³（P/m³）.
K is not only related to the geometric dimensions of the vortex generator and pipeline, but also to the Strouhal number. The Strouhal number is a dimensionless parameter that is related to the shape of the vortex generator and the Reynolds number. Figure 2 shows the relationship between the Strouhal number of a cylindrical vortex generator and the Reynolds number of a pipeline. As shown in the figure, in Re_D=2×10⁴～7×10⁶Within the range, Sr can be regarded as a constant, which is the normal operating range of the instrument. When measuring gas flow rate, the flow calculation formula for VSF is

Figure 2: The relationship curve between Strouhal number and Reynolds number

In the formula, q_Vn，q_V--Under standard conditions (0)^oC or 20^oC. 101.325kPa) and volumetric flow rate under operating conditions, m³/h；

Pn and P - are the pressures under standard and operating conditions, respectively, Pa；
Tn and T - are the thermodynamic temperatures under standard and operating conditions, respectively, K；
Zn and Z - are the gas compression coefficients under standard and working conditions, respectively.

3、 Advantages of nitrogen precision flowmeter products:
Not affected by temperature and pressure, and not easily clogged, stuck, or scaled, resistant to high temperatures and pressures.
▲ Safe and explosion-proof, suitable for harsh environments.
▲ No movable parts, no hollow gaps design, the product is wear-resistant, dirt resistant, does not require mechanical maintenance, and has a long service life.
▲ Adopting low-power high-tech and battery powered on-site display flowmeter, it can operate continuously for more than two years without electricity.
▲ Integrated design of voltage regulation and compensation.
▲ The current output is all electrically isolated, with good common mode interference suppression capability.
Simultaneously display the flow value and cumulative flow value, without the need to switch between them.
▲ Adopting anti vibration probes to effectively eliminate the influence of external vibrations.
The circuit adopts surface mount technology, with a compact structure and high reliability.
▲ Adopting a split type signal converter with a maximum cable length of 10 meters.
▲ The range ratio is as wide as 20:1.
The overall structural design is reasonable, the dynamic measurement range is wide, and the pressure loss is small.
The split type vortex flowmeter is made of stainless steel material and is suitable for measuring corrosive media.
▲ On site LCD display, pulse, 4-20mA output or 485 communication, can be connected to industrial automation systems.

4、 Parameter table of nitrogen precision flowmeter:

5Selection of nitrogen precision flowmeterTable:

6、 Installation diagram of nitrogen precision flowmeter: