Fire Streams (7th Edition)
Chapter 4-Developing Fire Streams (US)
Test Review

  • Fire hydraulics involves water flow, pressure losses, nozzle pressures/reactions, and pump discharge pressures.
  • Water discharge from an orifice is measured in GPM.
  • Water flow is dependent on the speed at which water flows and the size of the discharge opening.
  • Discharge velocity is the rate at which water travels from an orifice (measured in feet per second {FPS}).
  • Flow of water from any circular orifice is equal to the area of the orifice multiplied by velocity of water flow.
  • Total pressure loss is friction loss plus elevation loss.
  • Friction loss can be determined by actual tests (with measuring devices) or calculations (with equations).
  • Hoseline friction loss takes into account the construction of hose, length of hose, and quantity of water flowing.
  • A pitot tube or flowmeter and 2 in-line gauges are needed to test friction loss.
  • If using a pitot tube to measure friction loss, a smoothbore nozzle is required.
  • The 2 basic categories of hose layouts are "simple" and "complicated".
  • A simple hose layout can include: single lines, equal length multiple lines, equal wyed lines, and equal length siamesed lines.
  • A single line layout is the most common hose lay.
  • When rate of flow is increased in a hose, additional pressure is needed to overcome friction.
  • Complicated hose layouts may include: unequal length multiple/wyed lines, standpipe operations, manifold lines, and master streams.
  • If hoselines are of unequal length, FL should be calculated in each line to determine greatest FL.
  • Master stream devices may use multiple lines, siamesed lines, or LDH lines as supply lines.
  • Pump discharge pressure should be set at the highest of the lines flowing.
  • Fog stream nozzles tend to have greater nozzle reaction than solid stream nozzles due to higher operating pressure.
  • Pumping operations include pumping from hydrant, water tank, or draft.
  • Water tanks on apparatus are the most common source of water for firefighting operations.
  • Water distribution systems receive water from a pumping station.
  • The "First Digit Method" cannot be used with the metric system.
  • The elevation difference when drafting is known as "lift".
  • Water rises in the intake hose when drafting because of the greater atmospheric pressure outside the hose.
  • Net Pump Discharge Pressure (NPDP) is the difference between PDP and incoming pressure from hydrant.
  • When drafting, the Net Pump Discharge Pressure is greater that the pressure shown on the discharge gauge.
  • Dual pumping operations consist of 2 pumpers sharing 1 hydrant.
  • Tandem pumping consist of 1 pumper boosting the supply from a hydrant to another pumper.
  • Relay operations are based on the amount of water needed and distance from water source to scene.
  • A Constant Pressure Relay is the simplest method of relay pumping. All pumpers in the relay operate at the same pressure.
  • Pumpers in a Constant Pressure-Equal Distance relay are spaced farther apart than in the Maximum Flow method.
  • Hose size and layout will affect the distance between pumpers in a Constant Pressure-Maximum Flow relay, but will NOT affect the flow capacity of the relay.
  • The "attack" pumper in a relay controls the entire relay operation by coordination of attack line and dump line flows.
  • Relay operations should be shut down starting at the fire scene, working back to the source.
  • Source pumpers in a relay operation should maintain a small discharge through the dump line to avoid losing draft.
  • The "paddlewheel" flowmeter is the oldest type in the fire service.
  • "Spring-type probe" flowmeters are the most modern type of flowmeter.
  • Hydraulic calculators are either manual, mechanical, or electronic.
  • Pumper hookup to fire department connections should be maintained during overhaul.