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Gas monitoring specialists








Process manufacturing

Registered Office

76 Park Street


West Sussex

RH12 1BX

Gas Monitoring

Gas leak detection is an important part of every gas safety programme. Many industrial processes require the use of potentially toxic gases and other processes may generate hazardous gases as a bi product. Such hazards can be managed through careful equipment maintenance and regular monitoring for early signs of leakage. 

One of the primary concerns of a gas detection system is the protection of workers within the facility from the effects of toxic gas as well as oxygen depletion. Areas for protection are where gases could potentially build up and highly toxic or flammable combustible gases are stored, handled, transported or processed.  

Environmental Monitoring

For environmental monitoring the concentration of gases that need to be monitored is determined by the concentrations which are hazardous. Toxic gas sensors are normally ranged slightly above the short term exposure level (15min reference period). Gemlog equipment also provides a warning when the long term exposure limit is exceeded (8 hour TWA reference period).

Example: Carbon Dioxide (CO2) Long term 0.5% & Short term 1.5% Gemlog sensors are ranged to 2.0%

For further information consult HSE EH40/2005 Workplace exposure limits -  (Please note this link and document title was correct October 2012)

Flammable gas warning alarms are normally set at 20%LEL sometimes 10% LEL, with the second alarm at 40%LEL.

Oxygen depletion sensors are normally set to warning at 19% and full alarm at 17% oxygen. Gemlog Controls also offer an optional Oxygen enrichment alarm at 23%, this optional alarm may be deactivated at the controller.

Controller/Sensor Locations

There are no standards governing gas detection controller location. However we would suggest they should be mounted outside the room(s) being monitored and ideally in an adjacent corridor or room at typically head height.