Chemical oxygen generator

An oxygen candle is a steel cylinder which can deliver a large amount of bound oxygen in the context of an exothermic reaction.

Oxygen candles are used in areas where a reserve oxygen supply is necessary, which can be used without supplying additional energy at high reliability.

Function

The oxygen is usually bound in sodium chlorate (), which after ignition by a barium - iron powder mixture in the reaction

Decomposes, releasing oxygen. Alternatively, lithium perchlorate () is used, which is used for example on the ISS as " Emergency Oxygen Pack" ( EOP).

In general, the reaction is initiated by a mechanical trigger. Partial (steel cylinder) and briquettes ( charge with sodium chlorate, lithium perchlorate ) is differentiated according to containment.

Sodium chlorate based oxygen candle to reach reaction temperatures of about 600 ° C, those having lithium reach 450 to 500 ° C.

Areas of application

Oxygen candles are used, among other things, in the following areas:

• Submarines ( especially rescue systems such as ROV Scorpio)
• Space (eg space stations Mir and ISS)
• Aviation ( emergency oxygen systems for passengers in the event of decompression )
• Mining ( self-rescue systems, supply of emergency oxygens through tight supply shafts )

Hazards

A problem with the use of oxygen candles is the heat development associated with the desired oxygen evolution. The oxygen candle supplies with oxygen and heat two of three necessary components for combustion.

On the MIR led a defective oxygen candle almost to disaster. And the crash of ValuJet Flight 592 in the United States by the non-secure transport of old oxygen candles or an incident on the British nuclear submarine HMS Tireless in March 2007, in which two sailors were killed became known.

In particular, are often the systems allow not the obtained in the respiratory carbon dioxide ( CO2) free effluents (e.g., LiOH) provided with (CO2 ) filters in order to bind (CO2).

• Gas Technology