Common types of toxic gas detectors

Introduction to Toxic Gas Detection

Plants that produce chemicals, fertilizers, petroleum products, or facilities that produce oil and gas must deal with a variety of toxic chemicals in their daily operations. Many of these toxic chemicals are in the form of gases or vapors. This free Abhisam white paper provides a brief overview of the various toxic gas monitors used to detect these toxic substances.An example of use would be a detector for the highly toxic hydrogen sulfide gas. These detectors are also referred to as H2S detectors for short in the industry.

Why Use Toxic Gas Detectors?

Toxic gas detectors are primarily used to monitor the presence of harmful gases and vapors. These detectors are also known by many as Toxic Gas Monitors; the two terms are used interchangeably and mean the same thing.
These gas monitors enable workers working in factories with these toxic gases to protect themselves from exposure. One of them (a common harmful chemical) is hydrogen sulfide. The gas, which smells like rotten eggs, is highly toxic even in low concentrations. At lower concentration levels, the human nose can perceive this as a "bad smell", however, at higher concentration levels, as the human nose becomes desensitized, there is no any smell. So a worker who accidentally walks into a hydrogen sulfide environment could be knocked over and not notice anything unusual! Therefore, it is critical to have good, well-working toxic gas detectors in these locations to protect workers from accidental exposure.

For example, consider a process vessel in a chemical processing plant that typically contains hydrogen sulfide gas. During normal operation, the container will be hermetically sealed and no hydrogen sulfide will escape. However, if the container seal is not working (for example, a flange on one of the inlet pipes is leaking), this hydrogen sulfide gas is likely to escape and injure workers operating the container or those in the immediate area.

To prevent this from happening, a toxic gas detector that can measure hydrogen sulfide gas, even in low concentrations, is installed near the container. It will sound a warning alarm whenever dangerous levels of hydrogen sulfide are detected.

Types of Toxic Gas Detectors

There are a variety of technologies that can be used to create toxic gas detectors. These instruments also come in various forms such as stationary, portable or pocket. There are different sensors used to detect different types of toxic gases. Certain types of sensors can detect many different gases, while others can only detect one gas.

Fixed Toxic Gas Detector
These are common in large manufacturing plants and similar facilities. Each fixed gas detector is installed where there is a high probability of detecting toxic gases to prevent leaks. The detector may or may not have a local display showing the gas concentration. Each detector is connected by cables to a central system that is monitored by plant personnel. In the event of a leak, the panel will generate an alarm to warn the operator of the hazard, and can also perform any interlock actions (such as triggering a valve to close or initiating a shutdown).

Portable Toxic Gas Detector
Workers sweep work areas with portable gas monitors to see if any toxic fumes are lurking around the area. These detectors are also known as handheld gas detectors. These detectors are usually battery powered and have a display with a buzzer and indicator light to alert operators when dangerous levels of toxic gases are detected. They may have their own built-in sampling pump that draws air into the sensor. Some variants also store data to calculate time-weighted averages, peaks, and other important data for regulatory compliance.