Fire Apparatus Pump TheoryFire Apparatus Pump Theory

Section 180

Introduction Introduction Types of pressure encountered in the

fire service

Identify the types of fire pumps & components of pumps

Identify the function, theory, principles of operation of fire pumps

180-1.00

Types of pressures encountered Types of pressures encountered in the fire servicein the fire service

Static pressure

Residual pressure

Flow pressure

Normal operating pressure

Negative pressure

180-1.01

Static pressureStatic pressure

Static pressure is stored potential energy that is available to force water through a pipe, fittings, fire hose & adapters

The pressure exerted in all directions at a point in a fluid at rest

180-1.01a

Residual pressureResidual pressureThe pressure remaining in a

system while water is flowing

The total available pressure not used to overcome friction or gravity while forcing water through pipes, fittings, fire hose & adapter

180-1.01c

Flow pressureFlow pressureThe forward velocity pressure at a

discharge opening when water is flowing

180-1.01d

The rate of flow {velocity} of the water coming from the discharge opening produces this force called velocity or flow pressure

Water pressureWater pressure

Normal operating pressureNormal operating pressureThe pressure found in the water

distribution system during normal consumption demands

Occurs when some water is flowing in the system

180-1.01b

Grid systemGrid system

Negative pressureNegative pressure

Also called vacuum . Pressure that is less than atmospheric pressure

Negative pressure in the fire service is the result of drafting operations, which results from removing all the air from the pump & using atmospheric pressure to lift water from a source lower than the pump

180-1.01e

Terms related to the basic Terms related to the basic principles of fire service hydraulicsprinciples of fire service hydraulics

Atmospheric pressure – the atmosphere that surrounds the earth has depth & density & exerts pressure upon everything on earth

Capacity – The maximum amount of water a pump will deliver at the indicated pressure

Displacement – Movement of a given amount of a fluid w/ each stoke of a pump

Flow {GPM} – Gallons per minute, the measurement of the amount of water moved through a fire pump

Friction loss – Loss of pressure created by the turbulence of water moving against the interior walls of the hose or pipe.

Friction loss ex 1Friction loss ex 1

Friction loss ex 2Friction loss ex 2

Head Pressure (gain of loss) – Water pressure due to elevation. For every 1’ increase in elevation, 0.434 psi is gained. 1 M in height 10 kPa is gained

Hydrant pressure – The force of water when it enters the pump from the distribution system

Net engine pressure – The actual amount of pressure being produced by the pump

Nozzle reaction – The counterforce directed against the people or device holding a nozzle by the velocity of water being discharged

Pound per square inch PSI -

Pump discharge pressure – The actual velocity pressure (measured in PSI) if the water as it leaves the pump & enters the hose line.

Vacuum – A pressure that is less than normal atmospheric pressure

Velocity – The rate of motion of a particle in a given direction, speed

Water hammer – When the flow of water is suddenly stopped, the resulting surge is referred to as a water hammer

Water hammerWater hammer

BreakBreak

Thank Goodness

The firefighter shall identify & The firefighter shall identify & describe the following guages:describe the following guages:

Compound gauge – A gauge connected to the intake side of the pump that is capable of measuring positive & negative intake pressures

Discharge/pressure gauge – A gauge on the discharge side of the pump that registers the pump discharge pressure

180-1.03

Suction Pressure

Pressure lossPressure loss

Flow chartFlow chart