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
AGROSUN
A metal halide bulb manufactured exclusively
for Hydrofarm which puts out 38% more light in the red portion of the
spectrum than regular metal halide lamps.
AMPERE (AMP)
The unit used to measure the strength
of an electric current.
ARC
The luminous discharge of electricity
between two electrodes in HID lighting.
ARC DISCHARGE
A transfer of electricity across two
electrodes (anode and cathode), characterized by high electrode current
densities and a low voltage drop at the electrode.
ARC TUBE
The enclosure which contains the luminous
gases and also houses the arc.
BALLAST
An auxiliary piece of equipment designed
to start and to properly control the flow of power to gas discharge light
sources such as fluorescent and high intensity discharge lamps. In metal
halide systems, it is composed of the transformer, capacitor and connecting
wiring; sodium systems require an ignitor in addition to the transformer
and capacitor.
BU
An industry code indicating that the
bulb is to be operated only in a base up position.
BULB
The glass outer envelope component
of an HID lamp which protects the arc tube.
BULB WALL TEMPERATURE
The temperature at the bulb wall of
a lamp, which effects lumen output and input wattage and which is important
in lighting calculations.
CANDELA (CD)
A unit of luminous intensity in a
given direction, equal to one lumen per steradian.
CANDLEPOWER (CP)
The luminous intensity of a light
source, as expressed in candelas.
CANDLEPOWER DISTRIBUTION CURVE
A curve that represents the varying
distribution of luminous intensity of a lamp or luminaire.
CAPACITOR
An electronic device that can store
electrical charge. The capacitor is one of the main components of an HID
lighting ballast. Because they can store a very strong electrical charge,
capacitors can be very dangerous to someone who is unaware of this fact
and opens a ballast in order to examine or repair it. If one does not
know how to safely discharge the stored electricity, one should allow
a trained technician to do any ballast repairs.
COLD START TIME
The length of time required to bring
an HID lamp to 90% light output from a cold condition.
COLOR TEMPERATURE or KELVIN TEMPERATURE
The unit of measurement to express
the color (spectrum) of light emitted by a lamp; the absolute temperature
of a blackbody radiator having a chromaticity equal to that of the light
source (see correlated color temperature).
CONVERSION BULB
A bulb of a certain spectrum type
(e.g. sodium) specially designed to operate while used in the fixture/ballast
of a different type (e.g. metal halide). The most popular conversion bulbs
by far are sodium conversion bulbs, which allow one to have the sodium
spectrum while still using a metal halide system.
CORRELATED COLOR TEMPERATURE (CCT)
A specification of the color appearance
of a light source, relating its color to that of a blackbody radiator,
as measured in Kelvins (K). CCT is a general measure of a lamp's "coolness"
or "warmness."
DOME
The portion of an HID outer bulb located
opposite base (the neck and threads).
DOME SUPPORT
The spring-like brackets which mount
the arc tube within the outer envelope (bulb).
DISCHARGE LAMP
A lamp that produces light by discharging
an electric arc through a mixture of gases and gaseous metals.
ELECTRODES
Filaments located at either end of
a discharge lamp that maintain an electrical arc between them. See arc
discharge.
FIXTURE
The electrical fitting used to contain
the electric components of a lighting system.
FLUORESCENT LAMP
A discharge lamp in which a phosphor
coating transforms ultraviolet energy into visible light. Fluorescent
lamps are good for starting seedlings and rooting cuttings, but do not
have enough intensity to sustain aggressive growth in plants in the later
stages of life, and are not efficient enough in their conversion of electrical
power to lumens of light output.
FOOTCANDLE
A standard measurement of light intensity,
representing the amount of illuminance on a surface one foot square on
which there is a uniformly distributed flux of one lumen. More simply,
one footcandle of illuminance is equal to the light emitted by one candle
at a distance of one foot.
FREQUENCY
The number of waves or cycles of electromagnetic
radiation per second, usually measured in Hertz (Hz).
HALOGEN LAMP
A short name for the tungsten-halogen
lamp. Halogen lamps are high pressure incandescent lamps containing halogen
gases such as iodine or bromine which allow the filaments to be operated
at higher temperatures and higher efficacies. While excellent for home
lighting and similar applications, halogen lamps are not effective or
efficient as grow lights due to their limited spectrum and high operating
temperatures.
HID
The popular acronym for High Intensity
Discharge.
HIGH-INTENSITY DISCHARGE (HID) LAMP
A general term for mercury, metal
halide and high-pressure sodium lamps. HID lamps contain compact arc tubes
which enclose various gases and metal salts operating at relatively high
pressures and temperatures.
HIGH-PRESSURE SODIUM LAMP
High-pressure sodium lamps operate
by igniting sodium, mercury and xenon gases within a sealed ceramic arc
tube. Sodium lamps emit light energy in the yellow/red/orange regions
of the spectrum; the red spectrum stimulates flowering and fruit production.
Many indoor gardeners switch to sodium lamps when it is time to induce
flowering or fruiting of their plants.
HOOD
The reflective cover used in conjunction
with an HID lamp. The more reflectivity a hood can provide, the more effective
it is.
HOR
An industry code indicating that the
bulb is to be operated in a horizontal position.
HOT SPOT
The area immediately under an HID
lamp where the light intensity is strongest. Hot spots cause uneven growth,
but can be remedied by using light movers.
HOT START TIME
The length of time required to bring
an HID lamp to 90% light output after a short power interruption.
IGNITOR
A component of the ballast necessary
for the starting of the bulb in sodium systems.
ILLUMINANCE
The density of incident luminous flux
on a surface; illuminance is the standard metric for lighting levels,
and is measured in lux (lx) or footcandles (fc).
ILLUMINATION
The act of illuminating or state of
being illuminated. This term is often used incorrectly in place of the
term illuminance to denote the density of luminous flux on a surface.
INCANDESCENT LAMP
A light source which generates light
utilizing a thin filament wire (usually of tungsten) heated to white heat
by an electric current passing through it. Incandescent lamps are the
most familiar type of light source, with countless application in homes,
stores and other commercial settings. Light is produced by passing electric
current through a thin wire filament, usually a tungsten. Incandescent
lamps are totally ineffective as grow lights; they have very limited spectrum,
are very inefficient in their conversion of electrical power to lumens
of light output (lumen-to-watt ratio). They also put off far too much
heat per watt to use in horticulture, even if the above-mentioned problems
did not exist.
INTENSITY
A term referring to the magnitude
of light energy per unit; light intensity diminishes evenly as you get
further from the source.
KELVIN TEMPERATURE
(K)
The unit of measurement to express
the color (spectrum) of light emitted by a lamp; the absolute temperature
of a blackbody radiator having a chromaticity equal to that of the light
source (see correlated color temperature). A standard clear metal halide
HID lamp has an average Kelvin temperature rating of 4,000K.
KILOWATT (kW)
A unit of electric power usage equal
to 1,000 watts.
KILOWATT HOUR (kWh)
A measurement of electric energy.
A kilowatt hour is equal to 1,000 watts of power used over a period of
one hour.
LAMP
An electrically energized source of
light, commonly called a bulb or tube.
LAMP LIFE
A measure of lamp performance, as
measured in median hours of burning time under ANSI test conditions.
LAMP LUMEN DEPRECIATION (LLD)
The decrease over time of lamp lumen
output, caused by bulb wall blackening, phosphor exhaustion, filament
depreciation, and other factors.
LAMP STARTING
Generic term used to describe a discharge
lamp's starting characteristics in terms of time to come to full output,
flicker, etc.
LIGHT
Radiant energy which can be sensed
or seen by the human eye. The term generally applied to the visible energy
from a source. Light is usually measured in lumens or candlepower. When
light strikes a surface, it is either absorbed, reflected or transmitted.
Visible light is measured in lumens.
LIGHT MOVER (e.g. Hydrofarm’s
Light Track)
A motorized device which moves an
HID lamp back and forth across the ceiling of a grow room to provide more
even distribution of the light.
LUMEN
A measurement of light output; refers
to the amount of light emitted by one candle that falls on one square
foot of surface located at a distance of one foot from the candle.
LUMINAIRE
A complete lighting unit, consisting
of a lamp or lamps together with the components required to distribute
the light, position the lamps, and connect the lamps to a power supply.
Often referred to as a "fixture."
LUX
A standard unit of illuminance. One
lux is equal to one lumen per square meter.
METAL HALIDE LAMP
A high-intensity-discharge lamp in
which the light is produced by arcing electricity through a mixture of
metal halides. The light produced by metal halide lamps is in the white-blue
spectrum, which encourages vegetative growth and "bushiness"
while discouraging upward growth. This is the bulb to use in the first,
vegetative phase of plant growth.
MERCURY VAPOR LAMPS
The oldest member of the HID family,
mercury vapor lamps work by arcing electricity through mercury vapor.
While more efficient than incandescent, halogen and fluorescent lamps,
mercury vapor lamps have the least efficient lumen-to-watt ratio of the
entire HID family. This, combined with an improper color spectrum for
horticultural applications, makes mercury vapor lamps a poor choice for
a grow light.
NECK
The narrow, tubular end of the HID
bulb, attached to the threads.
PARABOLIC REFLECTOR
A lighting distribution control device
that is designed to redirect the light from an HID lamp in a specific
direction. In most applications, the parabolic device directs light down
and away from the direct glare zone.
PHOTOPERIOD
The relative periods of light and
dark periods within a 24-period. Also referred to as daylength.
PHOTOSYNTHESIS
The growth process by which plants
build chemical compounds (carbohydrates) from light energy, water and
CO2 (carbon dioxide).
PHOTOTROPISM
The gravitation of a plant part toward
a light source.
REFLECTOR
The term sometimes used to refer to
the reflective hood of an HID lamp.
REFLECTIVITY
The measure of the reflective quality
of a surface; the relative ability of a given surface to reflect light
away from it without absorbing, diffusing or otherwise compromising the
light’s quality, intensity and spectrum.
SOCKET
The threaded, wired receptacle that
an HID bulb screws into.
SODIUM LAMP (HIGH-PRESSURE SODIUM
LAMP)
High-pressure sodium lamps operate
by igniting sodium, mercury and xenon gases within a sealed ceramic arc
tube. Sodium lamps emit light energy in the yellow/red/orange regions
of the spectrum; the red spectrum stimulates flowering and fruit production.
Many indoor gardeners switch to sodium lamps when it is time to induce
flowering or fruiting of their plants.
SON-AGRO
A sodium bulb which, according to
the manufacturer, produces 30% more blue light than standard sodium bulbs.
The 430-watt SON AGRO also emits 6% more light than the standard 400-watt
sodium lamp.
SPECULAR REFLECTION
The redirection of incident light
without diffusion at an angle that is equal to and in the same plane as
the angle of incidence. The specular inserts included in Hydrofarm’s
HID lighting systems work on this principle.
STERADIAN
A unit solid angle on the surface
of a sphere equal to the square of the sphere's radius.
TRANSFORMER
The component in the ballast that
transforms electric current from one voltage to another.
U (for UNIVERSAL)
An industry code indicating that the
bulb can be operated in any position: horizontal, vertical (base up) or
any other.
ULTRAVIOLET (UV) LIGHT
Light with very short wavelengths,
out of the visible spectrum.
UNDERWRITERS LABORATORIES (UL)
A private organization which tests
and lists electrical (and other) equipment for electrical and fire safety
according to recognized UL and other standards. A UL listing is not an
indication of overall performance. Hydrofarm offers the only complete
line of growlight systems that is UL-listed.
WATT (W)
A unit used to measure electric power.
One watt equals one joule/second.
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