The working principle and selection of negative oxygen ion detector

The content of negative oxygen ions in the air is the key to good air quality. In the natural ecosystem, forests and wetlands are important places for generating negative (oxygen) ions in the air. It has a regulating effect in air purification and urban microclimate, and its concentration level is one of the indicators of urban air quality evaluation.

In nature, positive and negative ions in the air are generated under the impact of ultraviolet cosmic rays, radioactive materials, lightning, storms, waterfalls, and ocean waves. They are constantly produced and disappeared, maintaining a certain dynamic equilibrium state.

Because of the characteristics of negative ions, the generation and disappearance of negative ions in the empty space will maintain a balance. Therefore, judging the concentration of negative ions in the environment requires accurate measurement with a special air ion detector.

Negative oxygen ions are the general term for negatively charged single gas molecules and light ion groups, in short, negatively charged oxygen ions.

In the natural ecosystem, forests and wetlands are important places for generating negative oxygen ions in the air. Its concentration level is one of the indicators of urban air quality evaluation, and it is called 'air vitamin'.

Working principle:

The air ion measuring instrument is a special instrument for measuring gas ions in the atmosphere. It can measure the concentration of air ions, distinguish the positive and negative polarity of the ions, and can depend on the ions. The difference in mobility is used to distinguish the size of the measured ion. Generally, a capacitive collector is used to collect the charge carried by air ions, and the current formed by these charges is measured by a micro-amperometer. The measuring instrument mainly includes four parts: polarization power supply, ion collector, micro-current amplifier and DC power supply.

The first thing to understand is to choose the purpose of anion detection. At present, there are imported anion detectors, domestic anion detectors, counterfeit anion detectors and so on. It is divided into portable anion detector and online anion detector. According to the principle, it is divided into two types: parallel electrode anion detector and Yuantong capacitor anion detector.

Air negative oxygen ion detection is divided into two principles: 'flat plate method to measure air negative ions' and 'capacitance method to measure air negative ions'. Among them, the principle of 'flat plate' is a more commonly used method. , The detection is fast, economical and affordable, and is used for individuals, factories, laboratories and other units. Capacitance method is a high-performance detection method for measuring air negative ions. It has the characteristics of dustproof and moisture-proof. Compared with the flat plate method, it is more suitable for measuring air negative ions. It is especially suitable for forests and scenic areas. It is a forestry bureau and scientific research unit. Common instruments for measuring air quality.

According to the structure of the collector, the negative ion detector can be divided into two types: parallel plate type and Gerdien condenser type/double cylindrical shaft type.

1. Ebert type/parallel electric plate ion detector

The parallel electric plate ion detector is a commonly used method for low-end air ion detectors. A and B are a set of parallel and mutually insulated electrodes. There is a ring-shaped bipolar electrode at the top of the B pole. The air is sucked in by the fan in the lower right corner. The negative ion in the air hits the A/B electrode to discharge, and the charge is conducted to E. The ring electrode forms a self-discharge, and the discharge signal is recorded, so that the number and size of positive and negative ions in the air can be measured.

This kind of detector is technically mature, and the cost is relatively low, but it is easily affected by the external environment. In addition, the weakness of this structure can easily lead to electrolysis edge effects, which can easily cause airflow turbulence and result in detection results. The offset is large.

2.Gerdien condenser type/double cylindrical shaft type

The double cylindrical shaft ion detector is a mature method of the current mid-to-high-end air ion detector. The overall structure is composed of 3 concentric cylinders. The outer cylinder and the inner shaft are electrodes. When the air passes through the cylinder, the ions hit the cylinder and the shaft to generate discharge, and the discharge signal is recorded, so that the number and size of positive and negative ions in the air can be measured. Measurement.

This kind of detector is very mature in technology, but due to the complicated internal structure and control, the cost is high. This kind of structure can effectively solve the inherent electrolytic edge effect of the parallel electric plate structure. At the same time, the cylinder itself The structure and special air intake method can maintain the smoothness of the air flow, and greatly improve the detection accuracy of the number and size of ions.