Fire Hose

What Is Fire Hose?

Fire hose is broadly divided into attack lines and supply lines based on function and diameter. Attack lines, typically 1.5 to 2.5 inches in diameter, are advanced by crews to apply water directly onto a fire and are sized to balance flow rate against the hose's weight and maneuverability for interior or exterior attack. Supply lines, typically 3 to 5 inches in diameter (large-diameter hose, or LDH, generally refers to 4-5 inch supply line), move large volumes of water from a water source, usually a hydrant, to the pumping apparatus rather than being used to apply water directly. Hose is manufactured in standard section lengths, most commonly 50 feet, connected by couplings (most often NST/NH threads in the U.S.) that must match between hose sections, apparatus discharge/intake ports, and nozzles or appliances.

Why Fire Hose Matters on the Fireground

Selecting an attack line too small for the fire's flow requirement, or a supply line too small to keep up with the pump's demand, directly limits the volume of water that can reach the fire regardless of pump capacity, which is why hose diameter selection is matched to expected flow needs rather than defaulted to a single size for all fires.

Relevant NFPA Standards

• NFPA 1960: Standard for Fire Hose Connections, Spray Nozzles, Manufacturer's Design of Fire Department Ground Ladders, Fire Hose, and Powered Rescue Tools
• NFPA 1930: Standard on Fire and Emergency Service Use of Thermal Imagers, Two-Way Portable RF Voice Communication Devices, Ground Ladders, Rescue Tools, Fire Hose, and Fire Hose Appliances

Field Procedures & Tactical Steps

1. Select attack line diameter based on the fire's expected flow requirement, not a default single size.
2. Deploy supply line (LDH where available) sized to keep pace with the pump's water demand from the source to the apparatus.
3. Verify coupling compatibility before connecting sections from mutual-aid or unfamiliar apparatus.
4. Inspect hose for damage, proper coupling engagement, and kinks before charging the line.

Common Context & Application

Deployed as attack lines during fire suppression and as supply lines during hydrant relay or drafting operations; diameter and length selection are matched to flow requirements and water source distance.

Frequently Asked Questions about Fire Hose