PID sensor, full name PID photoionization gas sensor, works based on the principle of photoionization. Its working principle is as follows: the ultraviolet light (UV) light source inside the sensor turns organic matter (VOC gas) into positive and negative ions (ionization) that can be detected by the detector. Under the action of the electric field, the electrons and positively charged ions generated by ionization form a weak current, and the content of the substance is reflected by detecting the current intensity. Finally, we use electronic methods to detect the number of these ions to determine the concentration of the measured gas.
一. Functional characteristics of PID gas sensor
1. High precision, PID sensor has high sensitivity and can detect organic gas at the ppb level (one billionth). General photoionization gas sensors can detect organic gas at the ppm level (one millionth), with an accuracy higher than conventional sensors such as infrared, electrochemical, and catalytic combustion.
2. Non-destructive to the detected gas, good stability! The PID gas sensor ionizes the gas after inhaling it, and the ions formed by the gas molecules form the original gas molecules after discharge, without damaging the original gas molecules.
3. Fast response speed and long life. Under normal working conditions, PID gas sensors can respond almost in real time and can be tested continuously.
4. PID gas sensors can adapt to the detection of most VOC volatile organic compounds and some inorganic gases, and can be widely used in chemical, transportation, experimental analysis and other fields.
二. PID uses isobutylene as the standard gas for the following reasons:
1. Isobutylene has a relatively low ionization energy, Ie=9.24V, and can be ionized by ultraviolet lamps (UV lamps) of 9.8eV, 10.6eV, or 11.7eV.
2. The carbon chain length is 3, with 1 branch chain, and the molecule is neither large nor small, which is comparable to the size of most volatile organic compounds VOC, and is representative.
3. Isobutylene is low in toxicity and is in gaseous state at room temperature. As a calibration gas, it has no effect on the health of workers.
4. The price is not high and it is easier to buy.
5. Its concentration is also easier to check using other physical measurement methods.
三. Application scope of PID sensor
The application scope of VOC gas detector PID sensor is very wide, mainly including the following aspects:
1. Industrial production: In the fields of industrial production such as petroleum, petrochemical, chemical, pharmaceutical, etc., PID sensors are used to detect volatile organic compounds (VOCs). These compounds are easy to volatilize at room temperature, including benzene, toluene, xylene, formaldehyde, etc., which have serious effects on human health.
2. Environmental monitoring: PID sensors can detect VOCs and other toxic gases in ambient air, and are widely used in public health, indoor air quality monitoring and other fields. It can distinguish VOCs and other toxic gases in the concentration range of one part per billion (ppb) to one part per thousand (ppm), with a wide detection range and high sensitivity.
3. Emergency accident detection: In emergency accident detection, PID sensors play an irreplaceable role. VOCs are harmful substances in many gas accidents, and effective monitoring of these substances is of great significance for disaster prevention and mitigation.
4. Precautions for use: When using PID sensors, be careful to avoid blowing directly at the sensor and avoid using it in a high humidity environment to prevent condensation moisture from affecting performance. During storage, the humidity should be kept low and a desiccant should be used if necessary.