Editing Fire hose (section)

==Forces on fire hoses and nozzles==
Fire hoses must sustain high tensile forces during operation. These arise from both pressure and flow. The magnitude of the axial tension in a fire hose is

: <math display="inline">T = p A_1 + \rho Q^2 / A_1 ,</math>

where p is pressure in the hose relative to the ambient pressure, {{math|A<sub>1</sub>}} is the hose cross-sectional area, ''ρ'' is the water density, and Q is the volumetric flow rate.<ref name=Chin>{{cite journal|journal=Fire Technology S.K. Chin, P.B. Sunderland, G. Jomaas |title=Firefighter Nozzle Reaction (2017)|doi=10.1007/s10694-017-0661-3 |hdl=20.500.11820/e0cb178d-5a25-4d4b-9411-43eade26476b |s2cid=55141067|url=https://backend.orbit.dtu.dk/ws/files/137621163/Firefighter_Nozzle_Reaction_Chin_Jomaas_Sunderland_Fire_Technology_.pdf}}</ref> This tension is the same regardless of the bend angle of the hose.

When a nozzle is connected to a hose and water is ejected, the nozzle must be restrained by an anchor such as the hands of a firefighter. This anchor must apply a force in the direction of the spray, which is called the nozzle reaction. The magnitude of the nozzle reaction is the jet momentum flow rate,

<math display="inline">R = \rho Q^2 / A_2 ,</math>

where {{math|A<sub>2</sub>}} is the cross-sectional area of the nozzle.<ref name=Chin/>