Follow-up to Toxic gas emission from transponder (lithium batteries)
- Safety Flash
- Published on 1 January 2003
- Generated on 7 December 2025
- IMCA SF 01/03
- 3 minute read
We previously publicised this incident in safety flash 05/02 (Toxic gas emission from transponder). Following a detailed investigation by the manufacturer, who intends issuing new guidelines for dealing with flooded transponders, the Member involved has provided additional details on the incident and lessons learned on precautions to be taken in future.
What happened?
To summarise the event, a transponder, which had been at 600m, was received to a vessel and, after two hours, the safety relief valve on the transponder opened and a whitish cloud became visible. It was discovered that a gas had been created by the chemical reaction of water leaking into the transponder coming into contact with the lithium batteries. The gas was toxic, comprising sulphur dioxide and hydrogen chloride.
The manufacturer involved has issued the following points in anticipation of its new guidelines:
- Handling of a malfunctioning transponder
- Place the transponder in an open, safe place on deck, where there is plenty of free circulation of air. It should be able to be deployed back into the sea in case a hazardous situation occurs.
- The transponder should be left for at least two hours and monitored for points below.
- Check the transponder for external signs of water ingress.
- Check the transponder temperature. Temperature increase may indicate chemical reaction. Refer to ‘Handling in case of temperature increase’. Always keep clear of the line of the end cap and never point the end cap towards people or vital equipment when the transponder is being opened.
- Use the correct PPE as specified in 4. below.
- Handling in case of temperature increase in Lithium batteries
- For separate Lithium battery packs, immerse the battery in the sea.
- For transponders with an internal Lithium battery:
- Since there is a risk from toxic gases or explosion, all people not involved in the handling of the transponder should be cleared from the immediate area.
- Immerse the transponder in the sea. Check the temperature again after a few hours. The transponder must be cooled down in the sea until the temperature is around ambient and stable before it is opened.
- Cool down the transponder with sufficient water if it cannot be easily or safely lowered into the sea.
- Never point the end cap towards people or vital equipment when the transponder is being opened.
- Use the correct PPE as outlined in 4 below.
- The battery may then be electrically disconnected and separately deployed back in to the sea if appropriate.
- Handling in case of Lithium batteries catching fire
- Extinguish/cool down with sufficient water.
- Class D LithX fire extinguishers are not suitable for extinguishing a fire in Lithium batteries. (Such extinguishers are only for pure Lithium metal fires).
- PPE
- Opening a transponder with a defective battery: use goggles/rubber gloves/rubber or plastic apron/protective shoes.
- In case of sharp smell: use respiratory protection.
- Neutralise any reaction products and wash away with water.
- In case of fire: use respiratory protection with a full-face mask, fireproof clothing.
- Storage
- The same rules apply for transponders with internal Lithium batteries or for separate Lithium battery packs.
- Transponders/battery packs must be stored indoors in operational condition.
- They should be stored so that they remain stable in a relatively secure area away from people or vital equipment.
- Ideally there should be a fire extinguisher in close proximity.
- Transportation
- International transport regulations (the same regulations apply for transponders with internal Lithium batteries as for separate Lithium battery packs.
Related safety flashes
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IMCA SF 05/02
1 July 2002
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