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See also Fire Hose and Nozzles for manufacturer information (discharge & reaction charts, etc.)

Choice of Diameter Can Affect Firefighter Safety (Jeff Cowen)
The 2 ½” hoseline is perceived by many in the fire service as a defensive line only. A lack of fire-behaviour training and the perception that the 2 ½” hoseline is too difficult to advance and flow has made firefighters reluctant to use this hose as an interior-attack line.

Commerical Fire Attack
This terrific YouTube video provides a comparison of 2 1/2” and 1 3/4” hose lines, effective GPM delivery and ease-of-advancement.

Flow Rates for Firefighting.pdf (Paul Grimwood)
A recent survey of 58 UK fire brigades demonstrated that 89 percent of brigades were actually flowing far less water through their attack hose-lines than they realised and in some cases were flowing as little as 16 per cent of their target (nozzle specification) flow-rates! Further still, the influence of CFBT (Compartment Fire Behaviour Training) in the UK has encouraged a dangerous precedent – that less water means safer and more effective firefighting! This philosophy only holds true for gaseous-phase fire involvement restricted in area where beyond this amount of fire, a ‘highflow’ hose-line capability is essential for fire control. Situations whereby firefighters are ‘pulsing’ the smallest of flows into high volume gaseous-phase fires achieve far from the intended objectives of well-founded CFBT programmes and such approaches place firefighters at unnecessary risk.

A Quantitative Approach to Selecting Nozzle Flow Rate and Streams
Revisiting the issue of initial attack handline flow rates is critical, given the increase in flashover and rapid fire progression incidents that are injuring and killing firefighters in residential structure fires. Since contents in the typical residential structure in the United States have trended away from organic and cellulose-based materials toward a greater percentage of hydrocarbons, the American fire service must seriously reconsider the manner in which the NFPA 1710 initial attack flow rate is met and applied, as well as consider an increase in the minimum acceptable target flow rate. Today’s fire conditions leave little room for error.

The 2 ½” Handline: Gaining Relative Superiority (Brian Bush)
More is better: why 2 ½” should be the handline of choice even for engines with 3 firefighters. Many will use perceived staffing deficiency to explain away their ability to place anything other than a 1 ¾” into service. The misconception is that the 2 ½” always requires more people or is more complicated to operate; in many situations this is not true.

The Missing Tip and Optimum Handline Flow.pdf (Dennis LeGear)
Uncommon thoughts about commonly used suppression equipment: “The Missing Tip” and Optimum Handline Flow in 2 ½-inch Hose. A four part discussion:

• The Need to Address Maximum Deployable Handline Flow in 2 ½-inch Hose
• Nozzle Reaction as it Relates to Nozzle Pressure
• 2 ½-inch Hose Deployability and Optimum Flow
• Attack Handline Package Soltions and the 1 3/16-inch Tip

Take the Smooth Bore Test.pdf
TFT’s documentation that suggests that a combination nozzle is the best choice to provide maximum impact for any given flow at 100 PSI.

YYC Handline Kink Tests
It’s well known that kinks reduce flow in hoselines. Often though it is unknown what the actual effect of these kinks is and how different kinks affect flow. These tests performed in Calgary, Alberta demonstrate the necessity for stretching your dry lines clean, setting up properly before charging and ensuring that lines are kink free before committing to fire attack. It takes some practice but is very worth it.

Nozzle Reaction

How to Calculate Nozzle Reaction (US Forest Service)
Measuring and Demonstrating Nozzle Reaction
Nozzle Reaction (FE blog post by Brian Bush)

Nozzle Reaction Research Project Summary.pdf (Paul Grimwood)
“By evaluating maximum flow capability for a hose-line that could be effectively directed and safely handled whilst advancing and working inside a fire-involved structure It was observed that there was a maximum nozzle reaction force that could be handled by one, two and three firefighters as follows…”

Further Reading

Evaluation of Fire Flow Methodologies.pdf (Fire Protection Research Foundation)
There are a number of methods currently used to calculate required water flow rates for sprinklered and non-sprinklered buildings. These methods are, in general, based on decades-old criteria derived using data from actual fires. The overall objective of this study was to assess the appropriateness of currently available fire flow methodologies. The first task was a literature review of the existing fire flow calculation methodologies in the US and globally. The second task was a data analysis and GAP assessment to determine what additional information is needed to validate the existing fire flow calculation methodologies.

Spray Characteristics from Fire Hose Nozzles.pdf
This research examines the spray characteristics of fire hose streams. Smooth bore fire hose nozzles create jets with shear column breakup due to high Weber numbers. Laboratory settings produced a cylindrical water jet with the same column breakup behavior. The jet was injected into still air with fully developed turbulent flow. The test nozzle was oriented parallel to the floor. A patternator defined the shape and distribution of the spray. Shadowgraphy measurements determined the flow, drop size and velocity. The spray was tested in the middle of the liquid core.