Honeywell solution#1: Effective positioning of the sensor

“How many gas detectors do I need?” And “where should I put them?” Are two of the most frequently asked questions about gas detection systems, and perhaps two of the most difficult to answer. Unlike other types of related safety detectors, such as smoke detectors, the location and quantity of detectors required in different applications are not clearly defined.

Master guides can be found in standards such as EN 60079-29-2 and other standards related to selection,

installation, use and maintenance of equipment to detect and measure flammable gases or oxygen. International manipulation rules such as NEC or CEC can be used when applicable. In addition, the relevant authorities publish specifications for minimum gas detection requirements for specific applications.

Fixed gas forecast mounting position accordingly
Fixed gas forecast mounting position accordingly

The references are useful, but the inclination is either very generic and too roughly in detail, or specific applications and therefore inappropriate in most applications. The location of the detector should be determined on the advice of experts with professional knowledge in gas dispersion, in combination with the knowledge of process engineers/ equipment and safety officers. Agreements reached on the location of the detector should also be recorded.

Fixed gas forecasts are mounted where gases are more likely to be present. The site that requires the highest protection in industrial plants will be around gas boilers, air compressors, pressure tanks, rollers and pipelines. The leakage areas most likely to occur are valves, gauges, flanges, T-joints, filling or disconnection, etc.

There are some simple and fairly frequently clear considerations that help locate the newspaper:

  • To detect gases lighter than air (e.g. methane and ammonium), detectors should be mounted at a high level and it is best to use the tip of the autumn cone
  • To detect gases heavier than air (e.g. Butane and Sulfur dioxide), detectors should be mounted at low levels
  • Consider how air drainage can work due to natural or forced air flow. Attach the detector in the ventilation hose if appropriate
  • When installing a detector it is necessary to consider the damage that can be caused by natural events such as rain or flooding. For outdoor mounted detectors, it is very suitable to use protective panels
  • Use a sun shield for the detector if the detector is located in a hot climate and direct sunlight
  • Consider working conditions. Butane and ammonium, for example, are usually heavier than air, but if that gas escapes from a working pipeline where the temperature is high and/or there is pressure, the gas may rise rather than sink.
  • Detectors should be located a little away from high-pressure parts to allow gas clouds to form. Otherwise, any gas leak capable of passing through the high pressure gas line will not be detected
  • Consider how to easily access inspection and maintenance
  • Detectors should be installed in the specified locations with a downward pointer detector. This ensures that dust or water will not collect on the front of the sensor and prevent gases from entering the detector
  • When installing infrared devices remotely, it is important to ensure that there is no permanent obscuration or blocking of infrared rays. Short congestion from vehicles, construction workers, birds, etc.
  • Ensure the structure of the remote gas detectors is firmly mounted and not shaken.


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