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Oxygen (O2)

Oxygen Depletion Alarms

Applications - Research & Teaching Laboratories - Food & Manufacturing - Electronics

The Risk

If Liquid Nitrogen (or any other inert gas) is allowed to escape into the air, the Oxygen level is depleted. Since Liquid Nitrogen expands rapidly after it is released (1 litre of LN2 can expand to 680 litres), even a small amount of Liquid Nitrogen can, if released, reduce the Oxygen concentration by enough to cause danger. Depleted Oxygen levels are not just deadly, but initially impair physical and mental ability. This leads to an increased risk of accidents and other physical problems - see the section covering Oxygen in our Gas Information page for more details.

Common gases in use where Oxygen Depletion monitoring is used include Nitrogen, Helium (Special conditions neccessary - contact us for details), Argon and many others.

Oxygen Depletion monitoring should not be used where the target gas is Carbon Dioxide (CO2) since it is not sensitive enough to meet the effects of CO2 enrichment. For CO2 monitoring, see here Application Example - Combined Oxygen Depletion and CO2 Enrichment Monitor in a Laboratory Environment.

Whatever the specific risks, you can safeguard personnel against the danger of asphyxiation due to depleted oxygen levels by installing an Oxygen Depletion Alarm.

The Solution

Utilising the basic functions of our Oxygen Depletion Gas Alarm System, users of Liquid Nitrogen or other inert gases can monitor up-to 36 points around the workplace using our O2SafeGuardTM system, or alternatively up to 8 using the extremely cost effective 02SafeGuardLiteTM.

Oxygen Depletion sensors are distributed in the areas at risk, and are monitored by the central monitoring station. In a normal working environment, sensors are normally situated at around 1.25 metres above floor level, but this of course would be tailored to suit the circumstances of the application - for example for gases significantly lighter than air they would be mounted at high level. We can advise you on the best location for the sensors during a site survey or by inspecting site drawings. The Oxygen Depletion sensors usually have a range of 0-25% Oxygen, and are of the electro-chemical type. The system is normally set to give a first stage warning alarm at 19.0% Oxygen, and then a second stage full alarm at 17.0%. This enables action to be taken before an evacuation is required and evacuation before danger.

The Oxygen Depletion system has a User Interface, which for the O2SafeGuard TM is a full colour touch screen. Here it is possible to view the readings from the gas sensors, and indication is made audibly and visually if the system detects an alarm condition. O2SafeGuard TM also records (data-logs) the gas readings, and these can be recalled later and saved to a PC in a spreadsheet format. Normally sited with the O2SafeGuard TM User Interface is a small printer, which can be utilised to take records of testing, alarms and system set-up. It is advisable that the User Interface is located outside of the risk area, so that in the event of an alarm, the information from the system can be accessed without entry into the risk area.

In this example, the Oxygen Depletion system could be used to switch on or increase the speed of ventilation to the risk area to ensure an adequate Oxygen level. The system has two alarm settings. The first (Amber) Alarm can be utilised to trigger the ventilation, and the second (Red) Alarm be utilised to indicate evacuation of the area. The audible alarm is only triggered at the second (Red) Alarm stage. Either Alarm stage could be utilised to shut off the bulk storage supply of gas.

Application Specific Options

If you would like more information about Oxygen Depletion Alarms or Oxygen Depletion Monitors to book a no obligation consultation/survey, please contact us.

Related Information:

Application Example - Combined Oxygen Depletion and CO2 Enrichment Monitor in a Laboratory Environment.