Gas Detection Tubes
Gas Detection Tube is a device which detects the presence of various gases within an area, usually as part of a safety system. This type of equipment is used to detect a gas leak and interface with a control system so a process can be automatically shut down. A gas detection tube can also sound an alarm to operators in the area where the leak is occurring, giving them the opportunity to leave the area. This type of device is important because there are many gases that can be harmful to organic life, such as humans or animals.
Gas detection tubes can be used to detect combustible, flammable and toxic gases, and oxygen depletion. This type of device is used widely in industry and can be found in a variety of locations such as on oil rigs, to monitor manufacture processes and emerging technologies such as photovoltaic. They may also be used in firefighting. Gas detection tubes are usually battery operated. They transmit warnings via a series of audible and visible signals such as alarms and flashing lights, when dangerous levels of gas vapors are detected. As detectors measure a gas concentration, the sensor responds to a calibration gas, which serves as the reference point or scale. As a sensor’s detection exceeds a preset alarm level, the alarm or signal will be activated. As units, gas detectors are produced as portable or stationary devices. Originally, detectors were produced to detect a single gas, but modern units may detect several toxic or combustible gases, or even a combination of both types.
Types
Gas detection tube can be classified according to the operation mechanism (semiconductors, oxidation, catalytic, infrared, etc.).Gas detectors come in two main types: portable devices and fixed gas detectors.
Portable devices
Portable device is used to monitor the atmosphere around personnel and is worn on clothing or on a belt or harness.
Fixed gas detectors
Fixed gas detectors are fixed type which may be used for detection of one or more gas types. Fixed type detectors are generally mounted near the process area of a plant or control room. Generally, they are installed on fixed type mild steel structures and a cable connects the detectors to SCADA Systems for continuous monitoring and where a tripping interlock can be activated for an emergency situation.
Principle
The principle of gas detector tube system is a dry analysis method that makes an application of a chemical reaction and a physical absorption. In sampling a gas into a detector tube, a stained layer can be produced by means of the reaction of the reagent and gas in the tube. As the gas concentration is proportional to the length of stained layer, you can easily read off the concentration on the top of stained layer. The reading method of gas concentration are divided into two ways; a directly reading method of which reading can be obtained directly from the scale printed on the tube and a concentration chart method.