Gas Leak Detection: Placement Decides Effectiveness

Gas detection only works if the sensor sits where escaping gas will actually collect. That depends on the density of the gas relative to air.

Density decides mounting height

LPG is heavier than air. It sinks, pools at low level and collects in pits, trenches and floor voids — so detectors are mounted low, near floor level.

Natural gas is lighter than air. It rises and accumulates at high level, under ceilings and in roof voids — so detectors are mounted high.

Installing an LPG detector at ceiling height is a common and serious error. The device may pass a functional self-test for years while never being exposed to the gas it is meant to detect.

Other placement factors

• Position relative to the likely leak source — near joints, valves and appliance connections
• Air movement, since ventilation and air conditioning can carry gas away from a sensor
• Avoiding dead spots where air does not circulate
• Accessibility for calibration and sensor replacement

Sensors have a service life

Detection elements drift and eventually expire. A detector that powers up is not necessarily a detector that responds. Calibration intervals and sensor replacement periods are specified by the manufacturer and must be tracked — the power indicator tells you nothing about sensitivity.

Integration with response

Detection is only useful if something happens when it triggers. Decide in advance whether the system should sound an alarm, close a solenoid valve on the gas line, shut down appliances, or signal a building management system — and test that chain, not just the sensor.

Verification

Test with the intended detection method at commissioning and at each service interval, and record the results. Requirements for detection, alarm and shut-off arrangements are set by the applicable standard and the local authority.