6 |
WID EC U RE
®
C ON VEYO R U SER GU ID E
D YMAX. C O M
Checking the Workstation
The human eye cannot detect
“
pure
”
UV light, only visible light. A radiometer should be used to measure stray UV light to confirm
the safety of a UV light-curing process. A workstation that exposes an operator to more than 1 mW/cm
2
of UVA continuously
should be redesigned.
Protecting Operators
Light-curing technology can be a regulatory compliant,
“
worker-friendly
”
manufacturing process when the proper safety equipment
and operator training is utilized. There are two ways to protect operators from UV exposure: shield the operator and/or shield the
source.
Shield the Operator
UV-Blocking Eye Protection - UV-blocking eye protection is recommended when operating UV light-curing systems. Both clear and
tinted UV-blocking eye protection is available from Dymax.
UV-Blocking Skin Protection
Where the potential exists for UV exposure upon skin, opaque, UV-blocking clothing, gloves, and full-face shields are
recommended.
Shield the Source of UV
Any substrate that blocks UV light can be used as a shield to protect workers from stray UV light. The following materials can be
used to create simple shielding structures:
Sheet Metal
—
Aluminum, steel, stainless steel, etc. Sheet metal should be coated black or black anodized to minimize reflection
of UV and visible light toward operators.
Rigid Plastic Film
—
Transparent or translucent/UV-blocking plastics (typically polycarbonate or acrylic) are commonly used to
create shielding where some level of transparency is also desired.
Flexible Film
—
Translucent UV-blocking, flexible urethane films can be used to quickly create workstation shielding. This UV-
blocking, flexible urethane film is available from Dymax, call for assistance.
High-Temperature Surfaces
Surfaces exposed to high-intensity curing lights will rise in temperature. The intensity, distance, exposure time, cooling fans, and
the type/color of the surface can all affect the actual surface temperature. In some cases, exposed surfaces can reach
temperatures capable of producing a burn or causing damage to a substrate. In these cases, care must be taken to ensure either
a more moderate surface temperature or appropriate protection/training for operators.
Ozone
Standard Dymax bulbs (UVA type) generate an insignificant amount of UVC and therefore essentially no ozone. Some UV light-
curing systems, like those used to cure UV inks, emit primarily “shortwave” (UVB and UVC) energy. Upon exposure to UVC light
(specifically <240 nm), oxygen molecules (O2) split into oxygen atoms (O) and recombine with O2 to create ozone O3. The
current, long-term ozone concentration limit recommended by ACGIH, NIOSH, and OSHA is 0.1 ppm (0.2mg/m
3
).
