Safety and efficiency go hand in hand. Selecting an appropriate gas detection solution will not only maximise safety in your work area but also provide a more cost effective solution to monitoring air quality. Almost all industrial process involving organic and chemical compounds require continuous monitoring for various liquid and gas leaks. In some gases the depletion of required gases such as oxygen can also be detected.
There are two approaches to sensor placement, namely: point placement or perimeter placement. Point placement refers to placing detectors at key locations. E.g.: expansion valves, compressors, cable duct trenches or mechanical joints. While the installation point may depend on the sensitivity of the unit it is best not to install sensors any further one and a half meters from the target detection point.
Perimeter placement works on the principle of placing gas sensors along a predefined monitoring area perimeter. Setting each sensor unit at the centre of every wall in the room would be the typical way of setting up perimeter gas detection.
Generally speaking, professionals will distinguish between the physical gas sensor and the entire system. This is due to the sensor being considered to be one element of an integrated system. An Integrated Area Monitor refers to all portions of a gas detection system such as multiple sensors and transmitters that can be managed via one control panel.
When selecting an appropriate solution you will not only need to select the sensitivity range of a unit but also the type of sensor. The four broad categories for detection types are Infrared, Semiconductor, electrochemical and ultrasonic.
Infrared (IR) Point Sensors operate from the basic principle that radiation energy is absorbed at different wavelengths depending on the type of gases present. These units monitor for leaks by detecting radiation passing through a preset volume of gas. Examples of Infrared gas detection: Carbon Dioxide, flammable gases and other process emissions.
Semiconductor detection only works in direct contact with a gas and related chemical reactions. Examples of Semiconductor gas detection: Refrigerants, Hydrocarbons, VOC's and natural gases.
Electrochemical detection units utilise a porous membrane (customised to differing requirements) and an electrode. The concentration of gas creates a proportional electric current via this electrode. Examples of electrochemical gas detection: Ammonia, Ethylene, Chlorine, Fluorine, Silane, Co, H, No2, O2, Ozone & s02.
Ultrasonic sensors detect variations in the background noise (i.e.: acoustic changes) to detect the rate of leakage from a certain area.
Semiconductor and Electrochemical detection are only successful in cases where units come into immediate contact with gas. For this reason they generally tend to have a reduced sensitivity range when compared to Ultrasonic and Infrared point sensors. Ultrasonic detection is typically applied in areas that can be affected by external conditions such as outdoors or underground.
While most governments' emphasis on safety is controlled via legal requirements for workplace safety in industrial and commercial applications it is worth noting that gas detection in the home a growing safety consideration.