Home Safety & Fire Protection Glossary Terms

What Do Fire Extinguisher Class Letters Mean?

UK fire extinguishers are labelled by the type of fire they are rated to fight under BS EN standards: Class A covers solid materials like wood and paper, Class B flammable liquids, Class C flammable gases, Class D metal fires, and Class F cooking oils and fats. Extinguishers safe to use near live electrical equipment are separately marked, since standard water-based types are not.

Ionisation or Optical — What Is the Difference in Smoke Alarms?

Ionisation smoke alarms react quickly to fast, flaming fires but are more prone to false alarms from cooking fumes. Optical (photoelectric) alarms are generally more responsive to slow-burning, smouldering fires that produce more smoke than flame, which is why UK fire safety guidance commonly recommends optical alarms in hallways and escape routes, with ionisation types better suited away from kitchens.