Nozzles & Equipment
Master Stream
A master stream is a high-flow stream from a deck gun, monitor, or portable appliance — far more water than a handline, aimed by hardware rather than held by hand. Master-stream fog devices are built around about 80 psi at the tip.
When a fire is beyond what handlines can hold, a master stream delivers a large volume from a fixed or portable appliance. Because no one is holding the line, the device absorbs the heavy nozzle reaction the high flow produces.
The big flow makes water supply the limiting factor. Feeding a master stream usually means a strong hydrant, a relay, or a shuttle — the pump can only push the water the source can deliver.
Where this shows up
Calculator
Nozzle Flow & Reaction