PRODUCTS & SERVICES
led lamps designed for
safety and service in ndt
The latest LED lamps used in non-destructive
testing are safer and easier to handle
AEROSPACETESTINGINTERNATIONAL.COM // MARCH 2020 105
Ultraviolet radiation is used in fluorescent
penetrant and magnetic particle nondestructive
evaluation methods to
fluoresce materials used to indicate the
presence of flaws in safety critical
components. This is especially the case for
components used in the aviation, space, and
automotive sector. The specific radiation that
is used in these tests is governed by ASTM
E3022 and Rolls Royce 90061 and has a
wavelength of 365nm + or – 5nm. This
specific ultraviolet radiation wavelength
allows operators to work safely while
performing inspection using standard
personal protection equipment.
The process of creating Ultraviolet (UV-A)
radiation has evolved over the years and
today the use of instant-on LED technology is
prevalent in industry. Operator efficiency,
operator safety, and environmental safety are
maximized using LED UV-A technology. The
use of LED UV-A lamps implements a number
of safety advantages compared to other
methods, such as low temperature housings,
low voltage circuit design, lightweight design
and the elimination of the use of mercury.
Low voltage DC electrical energy, 18-24
volts, is high enough to produce LED UV-A
luminescence. This voltage can be produced
by battery power or by a wall outlet. This is a
tenth of the voltage required by other
technologies used in the past .
Filaments that operate at temperatures of
thousands of degrees in a vapor of mercury
have been eliminated using LEDs. This means
that skin burns caused by accidentally
bumping the light and the hazardous waste
streams from the disposal/breakage of bulbs
have been eliminated. LED’s are also small
components with high energy output. The
result is smaller and lighter packaging, which
directly results in a reduction of repetitive
motion injuries to operators.
However, the challenge with smaller
higher energy technology integration into the
light is controlling the heat around the LED
emitter. Around 30% of the electrical energy
input to the emitter goes to producing
luminous flux. This means 70% is waste heat
that must be controlled to keep the emitter at
a maximum of 140˚F or there will be
deleterious effects on emitter life. Design
approaches that ensure high heat flux in the
lamp body include using materials that have
high thermal conductivities like aluminum
and copper, minimizing the number of
internal contact resistances and maximizing
the surface area to transfer heat to the
surrounding environment.
In addition to thermal design
considerations, mechanical energy from
abusive treatment in service needs to be
included in the base design of a LED lamp.
The LED technology is robust and can survive
drops which produce hundreds of g’s.
Therefore, the connection system of the LED
emitter needs to be designed to isolate the
LED from drop events that happen in the
workplace daily.
Safe, long functioning tools like LED Lamps
will continually be developed to maximize the
utility of LED technology in non-destructive
testing. Non-destructive evaluations with LED
technology will maximize safety for travel
here on Earth and beyond. \\
1 // LED-UV A technology is
safer and smaller than older
sources used in lamps
2 // LEDs enable smaller and
lighter LED lamps
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