sprinkler glosary

7/30/2019 Sprinkler Glosary

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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

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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 fireprotection 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.

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J

Jockey pump: A jockey pump is a small capacity, high pressure pump used to maintain constant pressureson 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 /ft

4).

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 inprinciple 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 (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.

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.

sprinkler glosary

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