According to the standard: [GB 50493-2009;6.1 Installation of Detector (probe)]
1. The installation height of the combustible Gas Detector (probe) that is heavier than air should be 0.3~0.6m away from the floor (or floor). The Detector (Detector) for detecting toxic gases with a specific gravity greater than the air should be close to the leakage point, and its installation height should be 0.3~0.6m away from the floor (or floor), and the sensor part should be downward.
2. The installation height of the Detector (probe) for detecting combustible gas or toxic gas with a specific gravity less than air should be 0.5~2m higher than the release source, and the sensor part should be downward.
3. The Detector (probe) should be installed in a place without shock, vibration, strong electromagnetic field interference, and easy to maintain, and there should be no less than 0.5m of clearance and access channel between the place where the probe is installed and the surrounding pipelines or equipment.

关武 白旭 曹峰 - 《新疆维吾尔自治区计量测试研究院》
Miss黄 - 《南北潮商城》