How do they build up so much pressure to push out through fire hoses, yet they do not have enough pressure to break the fire hydrant? Where does the pressure come from?
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A fire hydrant is only an access point to a main. The 2 feet you see above ground goes 6-8 feet underground and hooks up with a water main. The steel is incredibly thick, and not to mention there is a long stem valve that goes down to the main, a fire hydrant doesn’t perpetually have water in it, only when the fire department hooks up to it. Not to mention, most fire hydrants are relatively low pressure, 60-100psi. Fire engines have very powerful pumps that take that water and increase the pressure. The fire department doesn’t use a fire hydrant to supply attack hose lines directly, but rather to supply an engine with water that then increase the pressure and puts it in specialized hoses for fire suppression. Hopefully that makes sense.
Tl;Dr, fire hydrants are relatively low pressure and don’t constantly have water in them.
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