Fire and Gas Detectors In the Oil & Gas Industry
Fire and gas detection system has paramount importance in an oil and gas processing facility. This article presents the fire and gas detectors used in process areas for the detection of fire or gas leakage in the oil and gas industry. In addition to this fire and gas system, personally wearable portable gas detectors or LEL detectors are also used.
Four types of detectors I have working experience with:
1. Point Watch Type
2. Open Path Type
3. Ultrasonic Type
4. Flame Detector
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1. Point Watch Type Gas Detector
Infrared
Hydrocarbon Gas Detector PointWatch Eclipse® Model PIRECL
This type of detector is point type and
works on infrared technology. It consists of a weather baffle assembly through which
the flammable hydrocarbon enters into its detection chamber i.e., IR transducers/sensors.
As the gas enters, certain IR wavelengths are absorbed in the gas(measure IR
wavelength), while other IR wavelengths pass through the gas(reference IR wavelength).
The absorption of IR wavelength then determines the concentration of flammable
hydrocarbon gas.
2. Open Path Type
This type of detector has its application for the detection of gas leakage across a perimeter. Open path type detector comprises a transmitter and a receiver. The transmitter and receiver at installed on poles at a distance up to 120 meters (max). This is the maximum distance for the Det-Tronics detectors; it can be reduced based on the area of application. Generally, the transmitter and receiver are installed at a height of 8~12 feet above ground. Please note that the actual height is subject to its area of application. To have a reliable operation of this detection device the line of sight is very critical. The transmitter and receiver pair should be 100% in the light of sight. A telescope is used to adjust and verify the line of sight. Mounting screws and adjustment clamps/screws are used to adjust the line of sight.
Working Principle:
It works on the Infrared technology.
3. Ultrasonic Type
Ultrasonic type or acoustic gas leak detectors are one of the latest technologies in the oil and gas market. It is a non-contact type gas detector meaning that this detection of gas leakage is not required to interact with the gas detector like in the infrared-based detectors discussed above. It works on the detection of ultrasonic frequency associated with the pressurized gas leak from a source. This gas detector is a state of the art application of digital signal processing which records the acoustic footprints from the pressurized gas leakage from a pinhole or any hydrocarbon flow line piping.
The manufacturer, Det-tronics claims that this gas detector has rugged noise cancellation or nuisance detection. However, as per personal experience, this depends on its application. We shall present details regarding its installation and commissioning experience in a separate article.
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