A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

B

• 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.

C

•  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.

D

• Darcy -Weisbach:  Technique used to establish the pressure lost to friction in a piping system.

• Differential manometer: A device whose primary application is to reflect the differences in pressures between two points in a system.

F

•  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.

G

•  Gridded piping system:  See complex loop

H

•  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 feet 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.

J

• 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.

K

•  Kinematic viscosity:  The kinematic viscosity of a fluid is the ration of its absolute viscosity (lb sec/ft²) to its mass density (lb sec²/ft⁴).

• Kinetic energy: The energy which a body possesses because of its motion.

L

• 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.

M

• 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.

N

• Net pressure:  The net pressure is the pressure added to the system  by the pump.

O

• 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. 

P

•  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).

R

• 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) .

S

• 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 (S_g) 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.

T

• 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.

V

• 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.

W

• 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.