Choosing the Optimal TVOC Sensor for Gas Detection

TVOC, or Total Volatile Organic Compounds, refers to a collective term for various organic compounds that can evaporate into gases at room temperature. These compounds include alkanes, aromatics, olefins, halogens, esters, aldehydes, and more. Exposure to TVOC can irritate the eyes and respiratory system, causing harm to the liver, kidneys, brain, and nervous system. Among indoor air pollutants, TVOC is considered one of the more severe. It encompasses organic substances with a saturated vapor pressure exceeding 133.32 Pa at room temperature and boiling points between 50°C to 250°C. TVOCs can exist in the air in an evaporative form, posing acute hazards due to their toxicity, irritability, carcinogenicity, and distinctive odor.

1. Types of TVOC Sensors: The TVOC sensor discussed here is a PID (Photoionization Detector) sensor, representing an advanced detection principle. This technology allows the extraction of over a hundred substances that can be ionized from TVOC. Its functionality is comparable to a portable Fourier-transform infrared (FTIR) spectrometer, a feature not achieved by TVOC sensors in other harmful gas detectors, making it an exclusive technology.

2. Measurement Range of TVOC Sensors: A single range sensor cannot suit all environments, and it is not scientifically practical. According to provided data, TVOC sensors can detect five different specifications: 0.0-20,000 ppb, 0.0-50,000 ppb, 0.0-200,000 ppb, 0.0-500,000 ppb, 0.0-2,000,000 ppb, and 0.0-10,000,000 ppb. The selection depends on the specific environment.

3. Operating Environment of TVOC Sensors: Different environments require sensors with different measurement ranges, which is a crucial factor in sensor selection. Low-range sensors offer high detection accuracy, whereas high-range sensors inherently have lower accuracy. For indoor air TVOC detection, it is advisable to choose a 0.0-20,000 ppb or 0.0-50,000 ppb sensor due to the low TVOC content. For outdoor atmospheric TVOC detection, a 0.0-50,000 ppb or 0.0-200,000 ppb sensor is recommended. In cases of pollutant source detection, a large-range sensor like 0.0-2,000,000 ppb is suitable, and for highly concentrated pollutant sources, such as leakage scenarios, a maximum-range TVOC sensor (0.0-10,000,000 ppb) is required.

4. Calibration Method of TVOC Sensors: Traditional TVOC sensors commonly use single-point calibration with air, which is simple and cost-effective but lacks precision due to the atmospheric TVOC background level of 50 ppb. However, the TVOC sensor from this manufacturer adopts a two-point calibration method using high-purity nitrogen gas for low values and isobutylene gas for high values. This method effectively avoids calibration errors induced by atmospheric TVOC, enhancing accuracy. Although this method incurs additional costs for purchasing calibration gases, it ensures the precision of TVOC detection.

Consideration of Measurement Range:

PPB Level: Low range, high accuracy – Suitable for environments with low concentrations of VOCs that may harm human health. Ideal for leak detection environments.

PPM Level: High range, low accuracy – Used in environments with higher concentrations of pollutants to measure VOC gas concentrations. Suitable for online monitoring of TVOC emissions.

PID-TECH Sensor: Advantages include sensors with four different measurement ranges, although detailed information is not publicly available. The CF table we obtained contains nearly 200 substances.

PID-A1 Sensor: Application information is more extensive, providing CF gases for over 400 substances.

In summary, choosing a TVOC sensor involves considering the type, measurement range, operating environment, and calibration method. The PID sensor, with its advanced technology, offers a wide range of applications and precise detection capabilities for diverse environments.