Firechief Water Additive Fire Extinguisher 6Ltr (34653)

Thank you for your question. This ESW3 unit is designed with an operating temperature between +5°C and +60°C so it may freeze if allowed to reach temperatures below this range. The additive is to reduce the surface tension of the water, thus making the water spray droplets smaller, producing a greater surface area in contact with the fire and therefore greater fire-fighting power than plain water. Subject to Fire Risk Assessment, you could consider using Powder Extinguishers as these have A, B and C ratings and Firechief units have an operating temperature range of -30°C up to +60°C, therefore can be stored/used outdoors.