Glossary for Fire Protection System
Content
Area of operation: The maximum area over which it is assumed that the sprinkler will operate and is some
time called the "assumed maximum area of operation"
Barometer: An instrument used for the measurement of atmospheric pressure
Bar: Is a unit of pressure 1 bar = 10000 pascal (Pa). The bar is used through Europe for the measurement of
pressure in fire sprinkler systems.
Bernoulli's equation: A mathematical expression of the principle of conservation of energy.
Booster pump: A fire pump used to boot the pressure of the existing water supply
Bourdon gauge: The most common device used to measure system pressures.
Centrifugal pump: Modern industrial fire pumps are centrifugal pumps. Pressure is added to the water by
the centrifugal force created by a rotating wheel (impeller) or the rotating vanes of a turbine.
Certified shop test valve: Before a pump is shipped by the manufacturer, it will be tested in the shop. The
results of this test will be plotted on graph paper.
Circulation relief valve: A small relief valve that opens up and provides enough water flow into and out of
the pump to prevent the pump from overheating when it is operating at churn against a closed system.
Complex loop: A piping system that is sometimes called a "grid" and is characterised by one or more of the
following: more than one inflow point, more than one outflow point, and/ or more than two paths between
inflow and outflow points.
Controller: The electric control panel used to switch pump on and off and to control its operation.
Darcy -Weisbach: Technique used to establish the pressure lost to friction in a piping system.
Desing Density: The density of discharge is given as mm/min and is the minimum amount of water which is
needed over the design area (or sprinkler head) for each minute of operation. The density of discard require of
any risk is dependent on the occupancies, classification of goods and the design standard been applied.
Desing Point: A point in the distribution pipe of a precalculated installation from where the pipework is sized
by hydraulic calculation
Differential manometer: A device whose primary application is to reflect the differences in pressures
between two points in a system.
Flow hydrant: The hydrant from which the water is discharged during a hydrant flow test.
Flow test: Tests conducted to establish the capabilities of water supply systems and referred to as flow tests
because they involve flowing fire hydrants. The objective of a flow test is to establish quantity ( gallons per
minute) and pressures available at a specific location on a particular water supply system.
Fluid: Any substance that can flow; a substance which has definite mass and volume at constant temperature
and pressure, but no definite shape; and with the inability to sustain shear stresses.
Fluid mechanics: In the general terms of physics, force is that which causes motion.
Force: In the general terms of Physics, force is that which causes motion.
Gridded piping system: See complex loop
Hardy cross method: An interactive technique used for solving the complicated problems involving gridded
water supply systems.
Hazen-Williams formula: An empirical formula for calculating friction loss in water systems that is the fire
protection industry standard. To comply with the most nationally recognised standards, the Hazen-Williams
formula must be used.
Head: Pressure expressed in units of Metre of water.
Horizontal split -case pump: A centrifugal pump with the impeller shaft installed horizontally and often
referred to as a split-case pump. This is because the case in which the shaft and impeller rotates is split in the
middle and can be separated exposing the shaft, bearings and impeller.
Hydraulics: The branch of fluid mechanics dealing with the mechanical properties of liquids (in the text
water) and the application of these properties in engineering.
Hydrokinetics: A branch of hydraulics having to do with liquids (water) in motion, particularly in relation to
forces created by or applied to the liquid in motion.
Hydrostatics: A branch of hydraulics dealing with the properties of liquids (water) at rest, particularly in
relation to pressures resulting from or applied to the static liquid.
Hydraulically most favourable area: Area of operation for which the water flow is at its maximum for a
specified pressure, measured at the main control valve or pump set
hydraulically most unfavourable area: Area of operation for which the system pressure, when measured at
the main control valve or pump set, is required to be at its maximum to achieve the specified design density
Jockey pump: A jockey pump is a small capacity, high pressure pump used to maintain constant pressures on
the fire protection system. A jockey pump is often used to prevent the main pump from starting
unnecessarily.
Kinematic viscosity: The kinematic viscosity of a fluid is the ration of its absolute viscosity (lb sec/ft 2) to
its mass density (lb sec2/ft4).
Kinetic energy: The energy which a body possesses because of its motion.
Laminar flow: A fluid is in the state of laminar flow if its Reynolds number is 2,100 or less; laminar flow is
related to very low liquid velocities.
Liquid: A fluid having a definite volume, unlike gases, which will expand to fill the vessel containing it.
Maximum flow demand: The flow discharge from the sprinkler heads located at the
hydranliclly most favourable area when balanced to a fire pumps flow / pressuer curve
(QMAX point)
Moody diagram: A Diagram used with the Darcy-Weisbach friction loss computation technique to relate the
Reynolds number, pipe size, and roughness to a friction factor.
Net pressure: The net pressure is the pressure added to the system by the pump.
Orifice plate meter: An orifice plate meter is a device used for measuring water flow and is similar in
principle to a Venturi meter. The change of water velocity is accomplished by using a plate with an orifice
that is smaller than the diameter of the pipe in which it is placed.
Pascal's law: Principle 1, known as Pascal's law, points out that pressure acts in all directions and not
simply downward.
Pascal: The SI unit for pressure is the pascal (Pa) which is equal to one Newton per
square meter (N/m2). For fire protection this measurement of pressure is small so the
unit Bar or kPa is used in most part of the world.
Piezometer tube: This device uses the heights of liquid columns to illustrate the pressures existing in
hydraulic systems.
Pitot tube: Common device used to measure velocity pressure and thus fluid velocity. The pitot tube
consists of a small diameter tube, usually about one-sixteenth inch in internal diameter which is connected to
a pressure gauge.
Potential energy: Stored energy which has the ability to perform work once released.
Pressure: is the force per unit area (symbol P).
Pressure head: Is a term used in fluid mechanics to represent the internal energy of a fluid due to the
pressure exerted on its container. It may also be called static pressure head or simply static head.
PSI: In fire protection, pressure is most often dealt within units of pounds per square inch (psi).
Relief valve: The relief valve is provided to open up and discharge water to a drain should the pressure
become excessive. This valve is located between the pump and the discharge check valve and is required
with pumps driven by variable speed drivers.
Residual pressure: The pressure at the test hydrant while water is flowing. It represents the pressure
remaining in the system while the test water is flowing.
Reynolds number: is a dimensionless number that state if the flow is in a laminar or turbulent stat (Symbol
Re) .
Simple loop: A loop in which there is exactly one inflow point and one outflow point, and exactly two paths
between the inflow and outflow points.
Specific gravity: The specific gravity (Sg) of a substance may be defined generally as the ratio of the weight
density of the substance to the weight density of another substance, usually water.
Static pressure: The normal pressure existing on a system before the flow hydrant is opened.
Total energy: The total energy (TE) at any point in a system might be defined as the sum of the potential
energy and kinetic energy at that point.
Turbulent state: Fluid flow is in the turbulent state higher velocities where there is no definite pattern to the
direction of the water particles. Turbulent flow is reflected by a calculated Reynolds number in excess of
2,100.
Venturi meter: When coupled with a differential manometer, a venture meter may be used to measure water
velocity. The device consists essentially of a piece of pipe in which the cross-sectional area has been
constricted.
Water hammer: Stopping any flowing stream too rapidly can cause a phenomenon called water hammer.
Water hammer is a violent increase in pressure which can be large enough to rupture the piping
Area of operation: The maximum area over which it is assumed that the sprinkler will operate and is some
time called the "assumed maximum area of operation"
Barometer: An instrument used for the measurement of atmospheric pressure
Bar: Is a unit of pressure 1 bar = 10000 pascal (Pa). The bar is used through Europe for the measurement of
pressure in fire sprinkler systems.
Bernoulli's equation: A mathematical expression of the principle of conservation of energy.
Booster pump: A fire pump used to boot the pressure of the existing water supply
Bourdon gauge: The most common device used to measure system pressures.
Centrifugal pump: Modern industrial fire pumps are centrifugal pumps. Pressure is added to the water by
the centrifugal force created by a rotating wheel (impeller) or the rotating vanes of a turbine.
Certified shop test valve: Before a pump is shipped by the manufacturer, it will be tested in the shop. The
results of this test will be plotted on graph paper.
Circulation relief valve: A small relief valve that opens up and provides enough water flow into and out of
the pump to prevent the pump from overheating when it is operating at churn against a closed system.
Complex loop: A piping system that is sometimes called a "grid" and is characterised by one or more of the
following: more than one inflow point, more than one outflow point, and/ or more than two paths between
inflow and outflow points.
Controller: The electric control panel used to switch pump on and off and to control its operation.
Darcy -Weisbach: Technique used to establish the pressure lost to friction in a piping system.
Desing Density: The density of discharge is given as mm/min and is the minimum amount of water which is
needed over the design area (or sprinkler head) for each minute of operation. The density of discard require of
any risk is dependent on the occupancies, classification of goods and the design standard been applied.
Desing Point: A point in the distribution pipe of a precalculated installation from where the pipework is sized
by hydraulic calculation
Differential manometer: A device whose primary application is to reflect the differences in pressures
between two points in a system.
Flow hydrant: The hydrant from which the water is discharged during a hydrant flow test.
Flow test: Tests conducted to establish the capabilities of water supply systems and referred to as flow tests
because they involve flowing fire hydrants. The objective of a flow test is to establish quantity ( gallons per
minute) and pressures available at a specific location on a particular water supply system.
Fluid: Any substance that can flow; a substance which has definite mass and volume at constant temperature
and pressure, but no definite shape; and with the inability to sustain shear stresses.
Fluid mechanics: In the general terms of physics, force is that which causes motion.
Force: In the general terms of Physics, force is that which causes motion.
Gridded piping system: See complex loop
Hardy cross method: An interactive technique used for solving the complicated problems involving gridded
water supply systems.
Hazen-Williams formula: An empirical formula for calculating friction loss in water systems that is the fire
protection industry standard. To comply with the most nationally recognised standards, the Hazen-Williams
formula must be used.
Head: Pressure expressed in units of Metre of water.
Horizontal split -case pump: A centrifugal pump with the impeller shaft installed horizontally and often
referred to as a split-case pump. This is because the case in which the shaft and impeller rotates is split in the
middle and can be separated exposing the shaft, bearings and impeller.
Hydraulics: The branch of fluid mechanics dealing with the mechanical properties of liquids (in the text
water) and the application of these properties in engineering.
Hydrokinetics: A branch of hydraulics having to do with liquids (water) in motion, particularly in relation to
forces created by or applied to the liquid in motion.
Hydrostatics: A branch of hydraulics dealing with the properties of liquids (water) at rest, particularly in
relation to pressures resulting from or applied to the static liquid.
Hydraulically most favourable area: Area of operation for which the water flow is at its maximum for a
specified pressure, measured at the main control valve or pump set
hydraulically most unfavourable area: Area of operation for which the system pressure, when measured at
the main control valve or pump set, is required to be at its maximum to achieve the specified design density
Jockey pump: A jockey pump is a small capacity, high pressure pump used to maintain constant pressures on
the fire protection system. A jockey pump is often used to prevent the main pump from starting
unnecessarily.
Kinematic viscosity: The kinematic viscosity of a fluid is the ration of its absolute viscosity (lb sec/ft 2) to
its mass density (lb sec2/ft4).
Kinetic energy: The energy which a body possesses because of its motion.
Laminar flow: A fluid is in the state of laminar flow if its Reynolds number is 2,100 or less; laminar flow is
related to very low liquid velocities.
Liquid: A fluid having a definite volume, unlike gases, which will expand to fill the vessel containing it.
Maximum flow demand: The flow discharge from the sprinkler heads located at the
hydranliclly most favourable area when balanced to a fire pumps flow / pressuer curve
(QMAX point)
Moody diagram: A Diagram used with the Darcy-Weisbach friction loss computation technique to relate the
Reynolds number, pipe size, and roughness to a friction factor.
Net pressure: The net pressure is the pressure added to the system by the pump.
Orifice plate meter: An orifice plate meter is a device used for measuring water flow and is similar in
principle to a Venturi meter. The change of water velocity is accomplished by using a plate with an orifice
that is smaller than the diameter of the pipe in which it is placed.
Pascal's law: Principle 1, known as Pascal's law, points out that pressure acts in all directions and not
simply downward.
Pascal: The SI unit for pressure is the pascal (Pa) which is equal to one Newton per
square meter (N/m2). For fire protection this measurement of pressure is small so the
unit Bar or kPa is used in most part of the world.
Piezometer tube: This device uses the heights of liquid columns to illustrate the pressures existing in
hydraulic systems.
Pitot tube: Common device used to measure velocity pressure and thus fluid velocity. The pitot tube
consists of a small diameter tube, usually about one-sixteenth inch in internal diameter which is connected to
a pressure gauge.
Potential energy: Stored energy which has the ability to perform work once released.
Pressure: is the force per unit area (symbol P).
Pressure head: Is a term used in fluid mechanics to represent the internal energy of a fluid due to the
pressure exerted on its container. It may also be called static pressure head or simply static head.
PSI: In fire protection, pressure is most often dealt within units of pounds per square inch (psi).
Relief valve: The relief valve is provided to open up and discharge water to a drain should the pressure
become excessive. This valve is located between the pump and the discharge check valve and is required
with pumps driven by variable speed drivers.
Residual pressure: The pressure at the test hydrant while water is flowing. It represents the pressure
remaining in the system while the test water is flowing.
Reynolds number: is a dimensionless number that state if the flow is in a laminar or turbulent stat (Symbol
Re) .
Simple loop: A loop in which there is exactly one inflow point and one outflow point, and exactly two paths
between the inflow and outflow points.
Specific gravity: The specific gravity (Sg) of a substance may be defined generally as the ratio of the weight
density of the substance to the weight density of another substance, usually water.
Static pressure: The normal pressure existing on a system before the flow hydrant is opened.
Total energy: The total energy (TE) at any point in a system might be defined as the sum of the potential
energy and kinetic energy at that point.
Turbulent state: Fluid flow is in the turbulent state higher velocities where there is no definite pattern to the
direction of the water particles. Turbulent flow is reflected by a calculated Reynolds number in excess of
2,100.
Venturi meter: When coupled with a differential manometer, a venture meter may be used to measure water
velocity. The device consists essentially of a piece of pipe in which the cross-sectional area has been
constricted.
Water hammer: Stopping any flowing stream too rapidly can cause a phenomenon called water hammer.
Water hammer is a violent increase in pressure which can be large enough to rupture the piping
