People need oxygen to live. It is vitally important that the oxygen concentration in the air we breathe remain above a minimum value. Therefore, oxygen sensors are installed in hazardous workplaces, which monitor the breathing air and warn if the oxygen content falls below a predefined level. 
In addition to oxygen deficiency, leaks of flammable or toxic gases can cause explosive or harmful atmospheres. Depending on the substances, which are handled, special sensors must be installed to protect employees from potential risks. These sensors monitor the threshold values for toxic and flammable gases in hazardous areas and trigger an alarm if environmentally harmful substances are released.
Sensors are adjusted to specific alarm limits. Their function must be checked regularly. For example, fixed sensors in explosion protection zones must be regularly checked with test gas mixtures with 20%, 40% or 50% of the Lower Explosive Limit (LEL). 
Messer offers a wide range of sensor test gases in cylinders or practical pressure cans.