Fixed Gas Detectors – Total Speed Of Response - Mads Kornbech and Martin T. Olesen

It is essential to provide a true picture of the actual response time of a gas detection system to understand the advantages of ultrasonic gas leak detection.

Ultrasonic gas leak detection technology works by listening for ultrasound emitted from pressurized gas leaks. The detectors do not have to wait until the gas concentration has accumulated to a dangerous gas cloud. This significantly reduces the response time.

Conventional point gas detectors can be based on at least two different principles. 1) Infrared (IR) sensors provide a measure for the gas concentration when gas gets absorbed by the infrared source. 2) Catalytic sensors provide a gas concentration based on a chemical reaction on the catalytic sensor element.

Conventional Gas Detectors – and response time
Historically, when referring to the response time for conventional gas detectors, it is often measured in seconds (using the term T90). However, this response time is based on gas being injected directly into the sensor head, which is not likely to be the case in an outdoor windy installation where the gas leak will be several meters away from the gas detector.

Therefore, when it comes to the total speed response time for a conventional gas detection system, it is important to also include the factor that the gas needs to accumulate and get from the leak point to the detector. Total speed of response for conventional gas detectors should therefore be calculated like this:

Ttotal = Tdetector + Tgas