Guidelines for the measurement of flammable gases

The Association of Swiss Installers of Security Systems (SES) has established the following guidelines:

For the monitoring of flammable and explosive gases, such as Methane CH₄, Ethanol C₂H₆, Propane C₃H₈, Butane C₄H₁₀, Pentane C₅H₁₂, Hexane C₆H₁₄ and Hydrogen H₂, the following points should be observed:

Number of gas sensors

At least two gas sensors must always be used in each room
The maximum monitoring area per gas sensor is 60 m²
The maximum distance from gas sensor to gas sensor must not be more than 10 m
The maximum distance from the gas sensor to a wall must not be more than 6 m
In corridors or rooms less than 3 m wide, the distance from gas sensor to gas sensor may not exceed 15 m

Installation of gas sensors

For gases with a density lower than air, the gas sensors must be mounted on the ceiling. For example: Hydrogen H₂, Methane CH₄ etc.
For gases with a density greater than air, the gas sensors must be mounted 30 cm above the floor. For example: Ethanol C₂H₆, Propane C₃H₈, Butane C₄H₁₀, Pentane C₅H₁₂, etc.
Special clarifications are required for certain gases. If in doubt, please contact us.

Installation of the gas control panel

A gas control panel should always be installed outside of the danger area.
A gas control panel should be in an easily accessible location.

Power outage

A gas control panel for flammable (explosive) gases must be backed up by a UPS.
The emergency power supply (UPS) for gas warning systems must ensure operation for at least 2 hours.

Servicing the gas warning system

Gas warning systems must be put into operation by the installer.
The gas measuring cells in the gas sensors are wearing parts and must be replaced every 1-5 years, depending on the type of gas.
A gas warning system must be checked and calibrated by the installer at least once a year. Depending on the application, shorter intervals may be necessary.
When servicing a gas warning system, the gas measuring cells must be replaced in accordance with the maintenance plan.