Wastewater Conveyance - Wastewater Operators - page 152

Soldering— A form of brazing that utilizes nonferrous filler metals
having melting temperatures below 800°F (427°C). The filler mate-
rial is called solder and is distributed between surfaces by capil-
lary action.

Solenoid— An electrically energized coil of wire surrounding a mov-
able iron case.

Stainless steel— An alloy steel having unusual corrosion-resisting
properties, usually imparted by nickel and chromium.

Strainer— An accessory fitting used to remove large particles of for-
eign matter from a fluid.

Throttle— Controlling flow through a valve by means of intermediate
steps between fully open and fully closed.

Tinning— Covering metal to be soldered with a thin coat of solder to
work properly. Overheating or failure to keep the metal clean causes
the point to become covered with oxide. The process of replacing
this coat of oxide is tinning.

Trap— An accessory fitting used to remove condensate from steam
lines.

vacuum breaker— A mechanical device that allows air into the pip-
ing system, thereby preventing backflow that could otherwise be
caused by the siphoning action created by a partial vacuum.

viscosity— The thickness or resistance to flow of a liquid.

vitrified clay— Clay that has been treated in a kiln to produce a glazed,
watertight surface.

Water hammer— The concussion of moving water against the sides of
a pipe, caused by a sudden change in the rate of flow or stoppage of
flow in the line.

4.4 fluids vs. liQuids

We use the term luids throughout this text to describe the sub-
stances being conveyed through various piping systems from one part of
the plant to another. We normally think of pipes conveying some type of
liquid substance, which most of us take to have the
same meaning as fluid; however, a subtle difference
exists between the two terms. The dictionary's defi-
nition of luid is any substance that flows—which
can mean a liquid or gas (e.g., air, oxygen, nitrogen). Some fluids carried
by piping systems include thick viscous mixtures such as sludge in a
semifluid state. Although sludge and other such materials might seem
more solid (at times) than liquid, they do flow and are considered fluids.
In addition to carrying liquids such as oil, hydraulic fluids, and chemi-
cals, piping systems carry compressed air and steam, which also are
considered fluids because they flow.

Key Point: Fluids travel through a
piping system at various pressures,
temperature, and speeds.