Plating Industry Glossary
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A.C.
An electric current which continually reverses its direction
of flow in a regular fashion. The vast majority of electricity
supply systems use A.C. The other system of electric current
transmission is Direct Current (D.C.).
abatement
The reduction of pollutant discharge by means
of process modification, shutdown or addition of control equipment.
absorber
A kind of scrubber utilizing the absorption principle.
ACFM
The actual gas volumetric flow rate (Actual Cubic Feet
per Minute).
acid
Chemical substance whose water solutions exhibit a
pH less than 7.
adsorbent
In addition to the adjectival meaning, the term
describes any of several substances that collect gaseous pollutants.
Used both for measurement and control.
aeration: the process or method of bringing about intimate
contact between air and a liquid.
air changes per hour (ACH) The movement of a volume of air
in a given period of time. If a building has one air change
per hour, it means that all of the air in the building will
be replaced in a one-hour period.
air contaminant
An impurity emitted to the outside air.
It can be solid, (dust, particulate matter), liquid (vapor,
mist) or gas (carbon monoxide, sulfur dioxide).
air curtain
Mechanical air-moving device designed to limit
the in-flux of unwanted air at a building opening.
air filter
An air cleaning device which removes contaminants
from an airstream.
air handling unit
Factory-made encased assembly consisting
of a fan or fans and other equipment to circulate, clean,
heat, cool, humidify, dehumidify or mix air.
air quality standards
The approximate concentration level
of a selected pollutant that is permitted in the atmosphere
to minimize detrimental effects.
air pollution
The presence in the atmosphere of gases, fumes
or particulate matter alone or in combination with each other,
in sufficient concentration to disturb the ecological balance;
cause objectionable effects, especially sensory offenses;
cause transient or chronic illnesses; or impair or destroy
property.
air, standard
Dry air at 70° F and 29.92 inches Hg barometric
and is approximately equivalent to 0.075 lb/ft
air velocity
Rate of speed of an airstream, expressed in
fpm.
altitude
The height above sea level of a given location.
Density corrections for altitude are made using the following
formula, where Z is the feet above sea level. Density (Alt)
= Density (Std) x [1 – (6.73 x 10-6) Z]5.258
anemometer
A device that reads air velocity such as a wind
vane. In fan applications, it is usually a spinning-vane-type
instrument used to read low velocities at registers and grills.
atmospheric pressure
One atmosphere is approximately 14.7
PSI; 407” water gauge. Airflow is the result of a difference
in pressure (above or below atmospheric) between two points.
axial fan
Fan where the airflow through the impeller is
predominantly parallel to axis of rotation. The impeller is
contained in a cylindrical housing.
axial flow
In-line air movement parallel to the fan or motor
shaft.
BACT (best available control technology)
An emission limitation
based on the maximum degree of emission reduction achievable
under Title 1 of the CAAA. EPA will establish BACT standards
for serious, severe and extreme nonattainment areas.
balancing
(1) on a fan, the process of adding (or removing)
weight on a rotor to move the center of gravity toward the
axis of rotation. (2) in a ventilation system, it’s
the process of measuring or calculating the airflow at a branch
and altering duct size or a valve to attain desired airflow
at that branch.
barometric pressure
A measurement of the pressure of the
atmosphere; standard is 29.92” Hg.
BI fan
Centrifugal fan with backward inclined blades that
move air more efficiently than straight blade fans. BI fans
are usually on the clean side of a piece of control equipment
as the blades are not especially abrasion resistant.
bio-HEPA filter
High-efficiency media air filter designed
to be 95% efficient on 0.3 micron and larger particles when
clean.
blast area
the fan outlet area less the projected area of
the cut-off.
blast gate
Sliding damper in a duct used to balance airflow
or to isolate a process from a system.
brake horsepower
The horsepower actually required to drive
a fan. This includes the energy losses in the fan and can
be determined only by actual tests of the fan (this does not
include the drive losses between motor and fan).
branch duct
Duct used to transport contaminants from a collection
point to a main duct or air cleaner.
British thermal unit (BTU)
Heat required to raise the temperature
of 1 lb. of water by 1° F. The BTU/hr. required to raise
the temperature of a volume of standard air by a specific
number of degrees is calculated by the formula:
Btu/hr = Temp. Rise x CFM x 1.085
capacitor start motor
Type of single-phase induction motor
with a capacitor connected in series with the starting winding.
High–starting and breakdown torque, medium starting
current. Used in hard-starting applications; compressors,
pumps, etc.
capture velocity
The air velocity at any point in front
of a hood or at a hood opening necessary to overcome opposing
air currents and to capture the contaminated air at that point
by causing it to flow into the hood.
carbon monoxide
A colorless, odorless gas that is toxic
because of its tendency to reduce the oxygen-carrying characteristic
of blood.
carrying velocity
The gas velocity that is necessary to
keep contaminants airborne. Usually between 2,000 to 5,000
ft/min in duct work, depending on the nature of the contaminant.
celsius
A thermometric scale in which water boils at 100°
and freezes at 0°, same as centigrade. °C = 0.5556
x (°F – 32°) 5/9 = 0.5556.
CFM
Volumetric flow rate expressed as Cubic Feet (of any
gaseous mixture) per Minute. See Also gas flow.
chemical abstracts service (CAS)
Registry Number is a numeric
designation assigned by the American Chemical Society’s
Chemical Abstracts Service, which uniquely identifies a specific
chemical compound.
collecting efficiency
The ability of a dust collector to
remove particulate from the exhaust gas. The ratios of particles
entering the collection device vs. particles leaving is expressed
in percent. inlet loading – outlet loading x 100 inlet
loading
combustible/explosive dust
Finely divided materials that
can cause or support combustion, such as aluminum, flour,
corn starch, etc.
combustion products
(1) Primarily gaseous matter such as
carbon oxides, nitrogen, oxygen and water vapor, resulting
from the combustion of fossil fuels. (2) In the context of
emission control, the gaseous products resulting from burning
any kind of material containing carbon in a free state or
combined state. Also referred to as “combustion contaminants.”
curve, fan performance
A graphic representation of static
or total pressure and fan BHP requirements over an airflow
volume range at a stated inlet density and fan speed.
D.C.
Direct current
An electric current which flows in
one direction only. Other system of electric current transmission
is alternating current (A.C.).
damper
Change in pressure, or pressure drop, that occurs
across a piece of control equipment.
dbA
Sound-pressure level corrected to the “A”
weighing network.
decibel
The logarithmic ratio between some known reference
and some quantity of electrical or acoustic signal power.
delta P (?P)
Change in pressure, or pressure drop, that
occurs across a piece of control equipment.
dew point
The temperature at which the equilibrium vapor
pressure of a liquid is equal to the existing partial pressure
of the respective vapor. (For air containing water vapor,
it is the temperature at which liquid water begins to condense
for a given state of humidity and pressure as the temperature
is reduced. For flue gas containing water vapor and SO3, it
is the set of conditions at which liquid sulfuric acid begins
to condense as the temperature is reduced.)
dry bulb temperature
The actual temperature of a gas, taken
with a conventional thermometer.
DSCFM (dry standard cubic feet per minute)
See gas flow
rate.
dust collector
An air-cleaning device used to remove heavy
particulate loadings from exhaust systems prior to discharge.
effluent
Any gas or liquid emerging from a pipe or similar
outlet; usually refers to waste products from chemical or
industrial plants as stack gases or liquid mixtures.
efficiency (air)
The relative ability of an air cleaner
to collect contaminants, usually expressed in percent. There
are many methods used to measure air cleaner efficiency. Results
achieved with different methods and contaminant samples may
not be directly comparable. Both the basis and test method
must be fully stated if efficiency figures are to be meaningful.
electrostatic dust
Particles that tend to receive and retain
a static charge, such as fiberglass, paint pigments, plastics,
etc.
elevation
The distance of the subject site above or below
sea level.
emission
Release of pollutants into the air, water, or ground
from a source.
equivalent duct diameter
For rectangular duct with sides
“a” and “b” is: D = (4ab/p)0.5
exhaust
The gases emitting from a plating or other process.
exhaust stack temperature
The temperature of the exhaust
gas, measured in the discharge stack.
exhaust volume
The amount of exhaust gas (air, products
of combustion and water vapor) leaving the exhaust stack;
usually measured in ACFM.
fahrenheit
A thermometric scalre in which water boils at
212° and freezes at 32°. °F = (1.8 x °C) +
32°.
fan
A power-driven machine that moves a continuous volume
of air by converting rotational mechanical energy to an increase
in the total pressure of the moving air.
fan capacity
Performance requirement for which a fan is
selected to meet specific system calculations given in terms
of ACFM at the fan inlet.
fan class
Operating limits at which a fan must be physically
capable of operating safely.
fan laws
Theoretical constant relationships between CFM,
RPM and BHP for a given fan used in a given fixed system:
CFM varies as RPM SP varies as (RPM)2 BHP varies as (RPM)3.
FC
Fan wheel design using forward-curved blades.
fan performance curve
A graphic representation of static
or total pressure and fan BHP requirements over an airflow
volume range at a stated inlet density and fan speed.
fan static pressure
The static pressure for which a fan
is to be selected based on system calculations: Fan SP = SP
outlet – SP inlet – VP inlet.
federal implementation plan (FIP)
Under current law, a federally
implemented plan to achieve attainment of an air quality standard,
used when a state is unable to develop an adequate plan. Under
the Senate bill, a plan containing control measures developed
and promulgated by EPA in order to fill gaps in a State Implementation
Plan (SIP).
filter area
Quantity of filter media available for collection
of contaminants. Expressed in square feet.
filtration
A means of separation where constituents are
separated usually by physical methods.
FPM (feet per minute)
Commonly defines air velocity (to
determine velocity pressure or suitability for material conveying),
shaft-bearing speeds (used to determine lubrication requirements)
and wheel tip speeds.
FRP
Abbreviation for fiberglass-reinforced-plastic.
fume scrubber
A device that uses a liquid spray to remove
aerosol and gaseous pollutants from an air stream. The gases
are removed either by absorption or chemical reaction. Solid
and liquid particulates are removed through contact with the
spray. Scrubbers are used for both the measurement and control
of pollution.
gas flow rate (cubic feet per minute CFM)
The volume of
process gas at any point of the plant exhaust system measured
in terms of minutes. There are several units of measurement:
gassing
The evolution of gasses from one or more of the
electrodes during electrolysis
HEPA filter (high efficiency particulate air filter)
Capable
of removing at least 99.97% by count of a standard 0.3 micron
challenge particulate (DOP test).
Hg
Symbol for mercury. Pressure is often measured in inches
of mercury: (1” Hg=13.64” WG).
hood
A shaped inlet designed to capture contaminated air
and transport it into the exhaust duct system. Hood types
include canopy, side draft, slotted, downdraft, etc.
humidity
Measure of the amount of water vapor in air.
humidity, absolute
The weight of water vapor per unit volume,
pounds per cubic foot or grams per cubic centimeter.
humidity, relative
The ratio of the actual partial pressure
of water vapor in a space, to the saturated pressure of pure
water vapor in a space, to the saturated pressure of pure
water at the same temperature.
HVAC
Heating, ventilating and air conditioning.
hydrophilic
Tendency to absorb water.
hydrophobic
Tendency to repel water.
impeller
Another term for fan “wheel”. The rotating
portion of the fan designed to increase the energy level of
the gas stream.
impeller diameter
The maximum diameter measured over the
impeller blade.
inch of water
A unit of pressure equal to the pressure exerted
by a column of water, one inch high at a standard temperature.
(407” WG = 14.7 PSI)
inches wg (inches of water gauge)
See inch of water.
indicator (pH)
A substance that changes color when the pH
of the medium is changed. In the case of most useful indicators,
the pH range within which the color changes is narrow.
kelvin
Absolute temperature in the SI system scale.
LAER (lowest achievable emission rate)
The rate of emissions
that reflects either the most stringent emission limit contained
in the implementation plan of any state (unless it is proved
that such limitations are not achievable, or the most stringent
emission limit achieved in practice, whichever is most stringent).
laminar flow
Gas or fluid in parallel layers with some sliding
motion between the layers.
liquid flowrate
The amount of water or “scrubbing
liquid” introduced into a wet collector.
louver
A device comprised of multiple blades, which when
mounted in an opening, permits the flow of air but inhibits
the entrance of undesirable elements.
low nox burner
One of several combustion technologies used
to reduce emission of Nox.
lower explosive limit
The lower limit of flammability or
explosibility of a gas or vapor at ordinary ambient temperature
expressed in percent of a gas or a vapor in air by volume.
Magnehelic® gauge
Gauge used for measuring pressure
drop across filter media. The gauge displays static pressure
in inches of water. This is a registered trademark of the
Dwyer Company.
make-up air
See replacement air.
manometer
A u-shaped device for measuring the static pressure
at a point relative to some other point. This pressure difference
causes water to rise or fall. The difference in the level
of the water columns is equivalent to the pressure differential.
membrane
A microporous structure that acts as a highly efficient
filter that allows passage of water, but rejects suspended
solids and colloidals; depending on membrane type, ions and
small molecules might or might not be rejected.
microbar
A unit of pressure equal to one-millionth of an
atmospheric pressure; 0.0000146 PSI.
mist
Suspended liquid droplets generally less than 10 microns,
generated by condensation from the gaseous to the liquid state,
or by breaking up a liquid into a dispersed state, such as
by splashing, foaming and atomizing.
motor starter
An electrical control device used to start
a motor and to protect the device from current overload condition.
A motor starter should be selected to match the operating
voltage and horsepower requirements of the motor.
MPH
Miles per hour.
MSDS (material safety data sheet)
Compilation of data and
information on individual hazardous chemicals produced by
the manufacturers and importers of that chemical, as required
by OSHA’s Hazard Communication Standard, 29 CFR 1910.1200.
NOX (nitrogen oxides)
Chemical compounds containing nitrogen
and oxygen. Reacts with volatile organic compounds in the
presence of heat and sunlight to form ozone. It is also a
major precursor to acid rain. Nationwide, approximately 45%
of Nox emissions come from mobile sources, 35% from electric
utilities, and 15% from industrial fuel combustion.
opacity
Refers to the amount of light that can pass through.
Normally refers to the degree of visibility of an exhaust
plume. Normal measurement technique used is by EPA method
9.
opposed-blade damper: a type of damper where the blades rotate
in the opposite direction.
OSI (ounces per square inch)
A unit of pressure equal to
one 1/16 PSI or 1.733 inches of water.
ozone
A compound consisting of three oxygen atoms, that
is the primary constituent of smog. It is formed through chemical
reactions in the atmosphere involving volatile organic compounds,
nitrogen oxides and sunlight. Ozones can initiate damage to
the lungs as well as damage to trees, crops and materials.
There is a natural layer of ozone in the upper atmosphere
that shields the earth from harmful ultraviolet radiation.
parallel fans
Two or more fans that draw air from a common
source and exhaust into a common duct or plenum. A parallel
fan arrangement is generally used to meet volume requirements
beyond that of a single fan. Two identical fans in parallel
will effectively deliver twice the rated flow of any one of
the fans at the same static pressure.
particle
A small, discrete mass of solid or liquid material.
particulate
A particle of solid or liquid matter.
particulate matter
Any solid liquid material in the atmosphere.
PEL (permissible exposure limits)
Limits developed by OSHA
to indicate the maximum airborne concentration of a contaminant
to which an employee may be exposed.
permit
An authorization, license or equivalent control document
issued by EPA or an approved state agency to implement the
requirements of an environmental regulation such as a permit
to operate a facility that may generate harmful emissions.
pH
A unit of measure depicting the hydrogen concentration
of a solution: Scale 1 to 14. Where 7 is neutral; <7 acidic;
>7 basic.
pH adjustment
The act of changing the pH of an aqueous solution
by adding acid or caustic.
pitot tube
A metering device consisting of a double-walled
tube with a short right angle bend. The periphery of the tube
has several holes through which static pressure is measured.
The bend end of the tube has a hole through which total pressure
is measured when pointed upstream in a moving gas stream.
plenum
Pressure equalizing chamber.
PPM (parts per million)
the number of parts of a given pollutant
in a million parts of air or water. Units are expressed by
weight or volume.
pressure, atmospheric
The pressure due to the weight of
the atmosphere. It is the pressure indicated by a barometer.
Standard atmospheric pressure is 29.92 inches of mercury.
pressure drop
The differential pressure between two points
in a system. The resistance to flow between the two points.
pressure, static
The potential pressure exerted in all directions
by fluid at rest. For a fluid in motion, it is measured in
a direction normally 90° to the direction of flow. Usually
expressed in inches water gauge when dealing with air.
pressure, velocity
The kinetic pressure in the directional
flow necessary to cause a fluid at rest to flow at a given
velocity. Usually expressed in inches water gauge.
PSI (pounds per square inch)
A measure of pressure .1 psi
equals 27.7” water gauge.
PSIA (pounds per square inch absolute)
The absolute pressure
without reference to another point. Atmospheric pressure is
14.7 PSIA.
PSIG (pounds per square inch gauge)
The pressure relative
to atmosphere. For instance, 10 PSIG equals 24.7 PSIA. This
is the more common pressure term.
radial blade
Fan wheel design with blades positioned in
straight radial direction from the hub.
random noise
A sound that has an average amplitude and constantly
changing frequency.
rarefication
A phenomenon related to negative pressure.
When air is drawn out through resistance into a fan inlet,
the air is stretched out, or rarefied, and becomes less dense
than at the entry to the system. While negligible at low pressures
and volumes, high-pressure fan selection must be based on
rarefied inlet density.
relative humidity
The ratio of existing water vapor to that
of saturated air at the same dry-bulb temperature.
replacement air
A ventilating term that refers to the replacement
of air lost because of exhaust air requirements.
Reynolds number
A mathematical factor used to express the
relation between velocity, viscosity, density and dimensions
in a system of flow. Used to define fan proportionality.
rotor
The rotating part of most AC motors.
RPM
Revolutions per minute.
saturated air
Air containing the maximum amount of water
vapor for a given temperature and pressure.
SCFM
The gas volumetric flow rate, corrected to 70°
F (standard temperature) and standard pressure (1atm) by calculation
(Standard Cubic Feet per Minute).
scrubber
A device that uses a liquid spray to remove aerosol
and gaseous pollutants from an air stream. The gases are removed
either by absorption or chemical reaction. Solid and liquid
particulates are removed through contact with the spray. Scrubbers
are used for both the measurement and control of pollution.
service factor
The number by which the horsepower rating
is multiplied to determine the maximum safe load that a motor
may be expected to carry continuously.
SIP (state implementation plan)
Documents prepared by states,
and submitted to EPA for approval, which identify actions
and programs to be undertaken by the state and its subdivisions
to implement their responsibilities under the Clean Air Act.
slot velocity
Linear speed of air through a slot in a hood,
expressed in Feet Per Minute (FPM).
source capture
A term used to describe applications in which
the airborne contaminant is picked up or “captured”
directly at the machine or process. Source capture applications
involve the use of ductwork to convey the contaminated air
to the air-cleaning device. Also sometimes called “direct
capture.”
specific gravity
The ratio of the weight or mass of a given
volume of any substance to that of an equal volume of some
other substance taken as a standard. The ratio of the density
of any gas to the density of dry air at the same temperature
and pressure is the specific gravity of the gas.
ssplit-phase motor
The most common type of single-phase
induction motor. Moderate starting torque, high-starting current,
high breakdown torque. Used on easy-starting equipment, such
as belt-drive fans.
squirrel-cage winding
A permanently short-circuited winding,
usually uninsulated and chiefly used in induction motors,
having its conductors uniformly distributed around the periphery
of the machine and joined by continuous end rings.
stack
A smokestack or exhaust stack. Vertical pipe or flue
designed to exhaust gases.
standard air density
0.075 lbs./ft3. Corresponds approximately
to dry air at 70°F and 29.92 in. Hg.
static balance
The mechanical balance of a rotating part
or assembly by adding weights to counter-balance gravitational
rotating of the part without power driving it.
static pressure (sp)
The potential pressure exerted in all
directions by fluid at rest. For a fluid in motion, it is
measured in a direction normally 90° to the direction
of flow. Usually expressed in inches water gauge when dealing
with air.
static pressure, fan
The static pressure for which a fan
is to be selected based on system calculations: Fan SP = SP
outlet – SP inlet – VP inlet.
STEL (short-term exposure limit)
The employee’s 15-minute
time weighted average exposure which cannot be exceeded at
any time. STEL is set by OSHA for each pollutant and expressed
in terms of ppm or mg/m.
SWSI
Single-width, single-inlet centrifugal fan.
synchronous speed
Rated motor speed expressed in RPM. Synchronous
speed = 120 x frequency, divided by number of poles.
system curve (air)
Graphic presentation of the pressure
versus volume flow rate characteristics of a particular system.
TEFC (totally enclosed, fan-cooled)
Totally enclosed motors
equipped with a cooling fan to prevent overheating.
threshold limit values (TLV)
Represents the air concentrations
of chemical substances to which it is believed that workers
may be exposed daily without adverse effect.
tip speed
Fan wheel velocity at a point corresponding to
the outside diameter of the wheel blades; normally expressed
in feet per minute (circumference times RPM).
TLV (Threshold Limit Value)
A registered trademark for an
exposure limit developed by the American Conference of Governmental
Industrial Hygienists (ACGIH). A listing of TLVs may be found
in the ACGIH’s Documentation of the Threshold Limit
Values and Biological Exposure indices for 1988-1989.
Toxic Release Inventory (TRI)
A listing of pollutants and
emission levels from each major source.
TP
Total pressure. The sum of velocity pressure plus static
pressure.
transformer
An electrical device that transfers energy from
one circuit to another by magnetic coupling with no moving
parts. Transformers provide a change in voltage, current,
phase or other electric characteristic during the transfer
and hence are used to convert between high and low voltages,
to change impedance, and to provide electrical isolation between
circuits.
transmitter
A wireless or radio transmitter; the set that
transmits or sends a wireless
trees
Branched or irregular projections formed on a cathode
during electrodeposition especially at edges and other high
current density areas.
TSCA (Toxic Substances Control Act)
Administered by the
EPA, was passed by Congress to protect human health and the
environment by requiring testing and necessary use restrictions
to regulate the commerce of certain chemical substances.
tubbeaxial fan
Axial fan without guide vanes.
TWA (time weighted average)
Employee’s average airborne
exposure which cannot be exceeded in any eight-hour work shift.
TWA is set by OSHA and expressed in mg/m.
ULPA filter
Ultra Low Penetration Air Filter designed to
be 99.997% efficient on 0.3 micron particles when clean
ultrafiltration
The process that uses membranes to achieve
separation of various constituents; a typical ultrafiltration
membrane allows water, ions, and small molecules to pass through
while rejecting large molecules and suspended solids.
unbalance
Tthe condition of a rotor in which its rotation
results in centrifugal force being applied to the rotor’s
supporting bearings.
upper explosive limit
The upper limit of flammability or
combustibility of a gas or vapor expressed in percent of gas
or vapor, in air, by volume.
velocity pressure
The kinetic pressure in the directional
flow necessary to cause a fluid at rest to flow at a given
velocity. Usually expressed in inches water gauge.
volt
Tthe standard unit of potential difference or electromotive
force, named after Alessandro Volta. One volt is the potential
difference across a conductor when a current of one ampere
dissipates one watt of power.
watt
A unit of power. In electrical terms, the product of
voltage and amperage. 746 watts are equal to one horsepower.
wet-bulb temperature
The temperature of a gas stream taken
with a wetted thermometer. It is approximately equal to the
adiabatic saturation temperature of the gas.
WR2
The unit designation of fan wheel rotational inertia
in lb-ft2 also know as WK2.