What does the value 'B1' indicate in fire extinguisher classification?

In fire extinguisher classification, the designation 'B1' specifically indicates that the extinguisher is suitable for Class B fires, which involve flammable liquids such as gasoline, oil, and grease. The '1' signifies the unit of measure in terms of effectiveness for a given volume of flammable liquid. This classification suggests that the extinguisher can effectively handle small quantities of flammable liquids.

The classification system helps users select the appropriate extinguisher type based on the class of fire they might encounter. Thus, 'B1' is a critical classification that indicates an extinguisher's capability to manage specific fire types effectively, ensuring safety and proper fire management procedures on vessels and other locations.

While the other choices present alternative interpretations, none correspond to the established meanings of fire extinguisher classifications. For instance, 'Not permitted on motor vessels' does not accurately reflect the 'B1' classification, which is indeed pertinent and relevant for use on vessels where flammable liquids may be present. Similarly, 'Class C fires' relate to electrical fires, and 'Specific weight class' is not a recognized component of the fire classification system.