Gas detection and test

The flammable gas detector is a detector installed in industrial and civil buildings that responds to single or multiple flammable gas concentrations.

The flammable gas detectors that are most frequently used in daily life are two types of catalytic flammable gas detectors and semiconductor flammable gas detectors.

In hotels, hotels, home-making rooms, and other places where gas, natural gas, and liquefied gas are used, semiconductor-type flammable gas detectors are mainly used, and industrial sites that emit flammable gas and combustible steam mainly use catalytic flammable gas detectors.

The catalytic flammable gas detector measures the concentration of combustible gas by using a change in resistance after heating of a refractory metal platinum wire.

When the combustible gas enters the detector, it causes an oxidation reaction (flameless combustion) on the surface of the platinum wire, and the heat generated by the heat causes the temperature of the platinum wire to rise, and the resistivity of the platinum wire changes, so when high temperature is encountered, etc. When the temperature of the platinum wire changes, the resistivity of the platinum wire changes, and the detected data also changes.

The semiconductor type flammable gas detector measures the concentration of combustible gas by utilizing changes in the surface resistance of the semiconductor.

The semiconductor flammable gas detector uses a gas sensitive semiconductor element with high sensitivity. When it is in operation, it encounters a combustible gas, the semiconductor resistance decreases, and the falling value has a corresponding relationship with the concentration of the combustible gas.

The flammable gas detector consists of two parts: detection and detection, with detection and detection functions.

The principle of the detection part of the flammable gas detector is that the sensor of the instrument uses a detecting element and a fixed resistor and a zero-setting potentiometer to form a detection bridge. The bridge uses platinum wire as the carrier catalytic element. After the power is applied, the platinum wire temperature rises to the working temperature, and the air reaches the surface of the component by natural diffusion or other means.

When there is no flammable gas in the air, the bridge output is zero. When the air contains flammable gas and diffuses to the detecting element, the flameless combustion is caused by the catalytic action, the temperature of the detecting element is increased, and the platinum wire resistance is increased. The bridge is out of balance, and thus has a voltage signal output. The magnitude of this voltage is proportional to the concentration of the flammable gas. The signal is amplified, analog-digital converted, and the concentration of the flammable gas is displayed through the liquid display.

The electrochemical gas detector is a gas detector using an electrochemical sensor. Since many gases are electrochemically active, they can be electrochemically oxidized or reduced, and the current generated by this reaction is proportional to the concentration of the reacting gas. Therefore, the composition and concentration of the gas can be detected by such a reaction.