Gas Detectors: What They Are and How They Work
A practical guide before choosing equipment: what a gas detector is, what sensor technologies exist, and when a portable or fixed model is advisable.
What is a gas detector and how does it work?
A gas detector is an instrument that monitors the concentration of a specific gas in the air and alerts when that concentration goes outside a safe range. The sensor comes into contact with the target gas — the air reaches it by natural movement (diffusion type) or a pump sucks it to the sensor (extractive type) — and that reaction is converted into an electrical signal proportional to the detected concentration.
A circuit compares that signal against a factory or site-configured alarm point; if exceeded, it triggers a visual and audible alarm and, in fixed models, also provides an output signal (dry contact or 4-20 mA) to a central alarm panel.
Types of Gas Sensors
New Cosmos Electric uses different sensor technologies depending on the target gas. These are the 4 actual principles present in their line:
Catalytic Combustion
Burn a small amount of combustible gas over a catalytic filament and measure the resulting temperature change. It is the principle of the combustible gas component in the XA-4400II series.
Electrochemical Cell
A chemical reaction between the target gas and an electrolyte generates a current proportional to the concentration. It is used for oxygen, CO, and H2S in the XA-4400II and XX-2200 series.
Infrared Sensor
Measures how much infrared light the gas absorbs at a specific wavelength. It is not consumed with use, so it needs to be calibrated less frequently — it is the basis of the KD-12R variant.
Interchangeable Semiconductor Sensor
A semiconductor element changes its electrical resistance in the presence of the target gas. The XPS-7II uses an interchangeable sensor unit (codes XDS-7) depending on the semiconductor manufacturing gas that needs to be monitored.
Portable or Fixed: Which Do You Need?
Portable Detector
It is worn by a person or used to check an area before entering — confined spaces, fieldwork, leak verification. It is quoted and calibrated individually.
Fixed Head
It is permanently installed at a point in the plant and connected to an alarm panel to monitor that area all the time — ovens, gas storage, process rooms.
Portable Gas Detectors
7 categories according to the target gas or application:
See Full Catalog →Fixed Gas Detector Heads
10 families of heads, either diffusion or extractive. Some of the most requested:
See Full Catalog →Frequently asked questions about gas detectors
Do you already know which model you need?
Tell us the gas, the application, or the model and we will contact you with the quote and availability.