4　Layout of Detection Points

4.1　Principles

4.1.1　Layout of combustible gas and toxic gas detectors shall be determined according to physichemical properties of the leaked gas，characteristics of the release source，layout of process equipments and structures，geographical conditions，climate，and operation and inspection routes.Detectors shall be installed at locations prone to gas accumulation and easy for sampling and detection.

4.1.2　Detection points shall be equipped for the following major release sources possible for combustible gas and toxic gas leakage:

1　Seals of gas compressors and liquid pumps；

2　Liquid sampling ports and gas sampling ports；

3　Liquid drains and vents；

4　Equipment and pipe flanges and manifolds.