Siemens flowmeterIt is an instrument that calculates flow based on the differential pressure generated by the flow detection component installed in the pipeline, known fluid conditions, and the geometric dimensions of the detection component and the pipeline. The Siemens flowmeter consists of a primary device (detection component) and a secondary device (differential pressure conversion and flow display instrument). Differential pressure flow meters are usually classified in the form of detection components, such as orifice flow meters, Venturi flow meters, and averaging tube flow meters.

The secondary device includes various mechanical, electronic, and electromechanical integrated differential pressure gauges, differential pressure transmitters, and flow display instruments. It has developed into a large category of instruments with a high degree of standardization (serialization, generalization, and normalization) and a wide range of types and specifications. It can measure both flow parameters and other parameters (such as pressure, level, density, etc.).

The detection components of Siemens flow meters can be divided into several categories according to their operating principles: throttling device, hydraulic resistance type, centrifugal type, dynamic pressure head type, dynamic pressure head gain type, and jet type. Testing items can be divided into two categories based on their standardization level: standard and non-standard. The so-called standard test piece is designed, manufactured, installed, and used according to standard documents, without the need for actual flow calibration to determine its flow value and estimate measurement errors. Non standard test pieces are those with poor maturity and have not yet been included in the standards.

Siemens flowmeter is a widely used type of flowmeter, accounting for the largest usage among various flow meters. In recent years, due to the emergence of various new types of flow meters, their usage percentage has gradually decreased, but they are still an important type of flow meter.

Advantages:

(1) The widely used orifice plate flowmeter has a sturdy structure, stable and reliable performance, and a long service life;

(2) It has a wide range of applications and there is currently no type of flow meter that can be compared to it;

(3) The detection components, transmitters, and display instruments are produced by different manufacturers, facilitating economies of scale production.

Disadvantages of Siemens flow meters:

(1) The measurement accuracy is generally low;

(2) Narrow range, generally only 3:1~4:1;

(3) High requirements for on-site installation conditions;

(4) High pressure loss (referring to orifice plates, nozzles, etc.).

　　Overview of Siemens flowmeter applications:

Differential pressure flowmeter has a wide range of applications, including flow measurement in closed pipelines for various objects such as fluids: single-phase, mixed phase, clean, dirty, viscous flow, etc; In terms of working conditions: normal pressure, high pressure, vacuum, normal temperature, high temperature, low temperature, etc; In terms of pipe diameter: from a few millimeters to a few meters; in terms of flow conditions: subsonic, sonic, pulsating flow, etc. It accounts for approximately 1/4 to 1/3 of the total usage of flow meters in various industrial sectors.

2-orifice flow meter

　　Advantages of Siemens flowmeter:

Standard throttling components are universal and recognized by standard organizations, and can be used without the need for actual flow calibration, including in flow meters. Easy to replicate, simple, sturdy, stable and reliable in performance, and affordable in price;

Widely applicable, including all single-phase fluids (liquid, gas, steam) and some mixed phase flows, with products available for pipe diameters and working conditions (temperature, pressure) in general production processes.

The detection components and differential pressure display instruments can be produced separately by different manufacturers, facilitating specialized scale production;

Disadvantages:

The repeatability and degree of measurement are at a moderate level in flow meters, but due to the complex influence of numerous factors, it is difficult to improve the degree. The range is narrow, and due to the correlation between flow coefficient and Reynolds number, the general range is only 3:1 to 4:1. There are long requirements for the length of straight pipe sections, which are generally difficult to meet. Especially for larger pipe diameters, the problem becomes more prominent; High pressure loss; Usually, in order to maintain the normal operation of an orifice flowmeter, the water pump needs additional power to overcome the pressure loss of the orifice plate. The additional power consumption can be directly generated by

Determination of pressure loss and flow rate calculation. It consumes tens of thousands of kilowatt hours of electricity per year, equivalent to tens of thousands of yuan. The table below lists the orifice plates under normal pressure

Energy consumption calculation results under loss conditions. The operating days are calculated based on 350 days, and the electricity price is calculated at 0.35 yuan/kWh. From the calculation of power consumption data in the table, it can be seen that the additional operating cost of the orifice plate is *, while the operating cost of using a bent tube flowmeter is zero!

The sharp angle line inside the orifice plate is used to ensure accuracy, so it is sensitive to corrosion, wear, scaling, and dirt. Long term use makes it difficult to guarantee accuracy, and it needs to be removed and inspected once a year. Using flange connections can easily lead to issues such as running, emitting, dripping, and leaking, greatly increasing maintenance workload.

3 Float flowmeter

Siemens flowmeter, also known as rotor flowmeter, is a type of variable area flowmeter. In a vertical conical tube that expands from bottom to top, the gravity of the circular cross-section float is supported by liquid dynamics, allowing the float to freely rise and fall inside the conical tube.

Float flowmeter is a type of flowmeter with a wide range of applications, second only to differential pressure flowmeter, and plays a crucial role in small and micro flow.

In the mid-1980s, sales in Japan, Western Europe, and the United States accounted for 15% to 20% of flow meters. The estimated production in China in 1990 was between 120000 and 140000 units, of which over 95% were glass cone tube float flowmeters.

Features:

(1) The glass cone tube float flowmeter has a simple structure and is easy to use, but its disadvantage is low pressure resistance and a high risk of glass tube fragility; (2) Suitable for small diameters and low flow rates;

(3) Low pressure loss.

4 Volumetric flowmeter

Positive displacement flowmeter, also known as fixed displacement flowmeter, abbreviated as PD flowmeter, is a high-precision type of flow meter. It uses mechanical measuring elements to continuously divide the fluid into individual known volume parts, and measures the total volume of the fluid based on the number of times the measuring chamber repeatedly fills and discharges that volume part of the fluid.

Volumetric flow meters can be classified according to their measuring components, including elliptical gear flow meters, scraper flow meters, dual rotor flow meters, rotary piston flow meters, reciprocating piston flow meters, disc flow meters, liquid sealed rotary cylinder flow meters, wet gas meters, and membrane gas meters.

Advantages:

(1) High measurement accuracy;

(2) The installation of pipeline conditions does not affect the measurement accuracy;

(3) Can be used for measuring high viscosity liquids;

(4) Wide range;

(5) Direct reading instruments do not require external energy and can directly obtain cumulative, total, clear, and easy to operate data.

Disadvantages:

(1) The results are complex and bulky;

(2) There are significant limitations in the type, diameter, and working state of the tested medium;

(3) Suitable for high and low temperature environments;

(4) Most instruments are only suitable for clean single-phase fluids;

(5) Generate noise and vibration.

Application Overview:

Volumetric flow meters, differential pressure flow meters, and float flow meters are classified as three types of flow meters with high usage, commonly used for measuring the total amount of expensive media such as oil and natural gas.

In recent years, the sales amount of PD flow meters (excluding household gas meters and household water meters) in industrial development has accounted for 13% to 23% of flow meters; China accounts for about 20%, with an estimated production of 340000 units in 1990 (excluding household gas meters), of which elliptical gear type and waist wheel type account for about 70% and 20% respectively.

5 Types of Sewage Flow Meters

　　Siemens flowmeterClassified by measurement principles:

1. Flow meters include throttling flow meters, pitot tube flow meters, averaging tube flow meters, rotor flow meters, and target flow meters. These flow meters use the Bernoulli equation principle to reflect flow by measuring fluid differential pressure signals;

2. Flow meters include turbine flow meters, vortex street flow meters, electromagnetic flow meters, Doppler ultrasonic flow meters, and hot wire speed measurement flow meters, which reflect flow rate by measuring fluid flow velocity;

3. Flow meters include gear flow meters, scraper flow meters, and rotary piston flow meters, which reflect flow rates by measuring small volumes of standard volumes;

4. Flow meters include thermal mass flow meters, differential pressure mass flow meters, impeller mass flow meters, Coriolis mass flow meters, and indirect mass flow meters, which reflect flow by measuring fluid mass;

5. The flow meter has a weir type flow meter, which reflects the flow rate by measuring the liquid level.

　　Siemens flowmeterFeatures:

1. The sewage flowmeter has a simple structure, is sturdy and reliable, and has a long service life.