Functionality of Fixed Gas Detectors
A fixed gas detector relies on gas sensors to identify and measure specific gases in its surroundings. These sensors detect the type and concentration of gas, making them important in environments like petroleum refining, chemical plants, fire safety, fuel handling, telecommunications, coal mining, and industrial production.
The detector typically consists of two parts:
- Gas Detector: Identifies gas concentrations near the sensor.
- Control Panels: Analyses the detected data, triggers alarms, and uploads information to a safety control system.
Installation Guidelines
Key considerations for installing fixed gas detectors include:
- Positioning:
- Place sensors within 1 metre of potential leak points, such as valves, pipe joints, or outlets. Avoid areas with high vibration, extreme temperatures, or electromagnetic interference.
- Protect detectors from external damage, like water spray or oil spills, and ensure maintenance access is easy.
- Height Adjustment:
- For heavier gases, such as propane or chlorine, install detectors towards the ground.
- For lighter gases, such as ammonia or hydrogen, position them above the leakage source.
- Controller Placement:
- Install alarm controllers in non-explosive areas, like control rooms. Use ATEX approved control panels if located on-site in hazardous zones.
Rockall Safety can install your fixed gas detector for you. Get in contact with the team today – Contact Us | Equipment Specialists & Service Providers | Rockall Safety
Bump Test/Calibrating a Fixed Gas Detector
Bump Test
A bump test is a quick functional check where sensors are briefly exposed to gas at a sufficient concentration to trigger alerts or alarms. The purpose is to confirm that the sensor and device are operating correctly. Unlike a calibration check, a bump test does not measure sensor accuracy; it simply verifies that the sensor responds to gas and activates alarms as intended.
If a detector fails, it may not respond to the gas or may take too long to trigger an alarm. This could be due to debris obstructing the sensor or the sensor requiring recalibration. Always refer to the manufacturer’s instructions for specific bump test procedures, as these can vary between different models of gas detectors.
Calibration
Calibration involves testing a gas detector with a known gas concentration to confirm it functions within the manufacturer’s specified tolerances. The process begins with establishing a baseline, typically in clean air. For most toxic and combustible gases, this baseline is zero, while for oxygen it is 20.9%. Once the reference point is set, a test gas of known concentration is applied. The gas concentration should be high enough to trigger an alert or alarm without exceeding the detector’s maximum range. If the detector’s reading is within the acceptable range of ±10-15% of the test gas concentration, the calibration is valid. If not, recalibration is required. (Always refer to the manufacturer’s instructions for specific acceptable ranges.)
Rockall Safety are on hand for all fixed gas detection needs. If you have any queries on fixed gas detection, please get in contact.
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