What Is a Gas Flow Measurement System?
A gas flow measurement system is a device designed to measure gases with specific properties present in the air.
These gases include flammable, toxic, inert, and combustible gases. Gas flow measurement systems are crucial for detecting gases that pose direct dangers to humans or are potentially flammable.
Various measurement methods exist, tailored to the gas’s specific characteristics. These include devices that leverage optical properties and those measuring physical properties.
Applications of Gas Flow Measurement Systems
Gas flow measurement systems are vital for detecting leaked flammable or toxic gases in the atmosphere and measuring their concentrations. Since these gases are often colorless and undetectable by humans, they can pose significant risks. Common devices include methane, carbon monoxide, and carbon dioxide measuring instruments.
These instruments are designed to measure gas concentrations continuously, as well as short-term and long-term cumulative concentrations. It is essential to select a method that accurately detects the target gas’s concentration without interference from other gases.
Types of Gas Flow Measurement Systems
Gas flow measurement systems are categorized into solid-state sensors, electrochemical sensors, and optical sensors.
1. Solid-State Sensor
Examples of solid-state sensor technologies include the catalytic combustion method, new ceramic method, semiconductor method, hot wire semiconductor method, and thermoelectric method.
2. Electrochemical Sensor
Electrochemical sensors utilize techniques such as the constant potential electric field method, diaphragm-separated constant potential electric field method, diaphragm electrode method, and diaphragm galvanic cell method.
3. Optical Sensor
Optical sensors employ methods like the infrared method, detection tape method, and thermal particle method.
Structure of Gas Measuring Systems
Catalytic combustion sensors measure combustible gas concentrations by utilizing the heat generated during combustion, with changes in the resistance of a platinum wire coil indicating gas concentrations.
Principles of Gas Flow Measurement Systems
1. New Ceramic Type
New ceramic sensors measure combustible gases using the heat generated upon combustion over an ultra-fine oxidation catalyst.
2. Semiconductor Type
Semiconductor sensors detect gases through changes in resistance when a metal oxide semiconductor interacts with the gas.
3. Hot Wire Semiconductor Type
Hot-wire semiconductor sensors detect flammable gases through changes in electrical conductivity resulting from gas adsorption and oxidation reactions on oxide semiconductor surfaces.
4. Heat Conduction Type
Heat conduction sensors differentiate gases based on their thermal conductivity by exposing them to a heated element.
5. Constant Potential Electrolysis Method
Constant potential electrolysis sensors measure gas by the current generated during electrolysis at a constant electrode potential.
6. Diaphragm Galvanic Cell Type
Diaphragm galvanic cell sensors detect oxygen concentrations by measuring the current generated during oxygen electrolysis on an electrode.
7. Infrared Type
Infrared sensors measure gas concentrations based on the absorption of infrared rays emitted from an internal light source by the gas.
How to Choose a Gas Flow Measurement System
When selecting a gas flow measurement system, consider the specific gas types, environmental conditions, and required sensitivity. Each sensor type offers unique advantages, such as response time, accuracy, and longevity, suited to different applications.