Labconco CAptureTMPortable Fuming System 3420024 - Manual (Page 9)

Chapter 3: Theory of Operation & Safety Precautions
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(polycyanoacrylate) on the fingerprint ridges. The ridges can then be
recorded. The developed fingerprints are, on most surfaces (except on white
plastic or similar), visible to the naked eye. The reaction must be monitored
to ensure that it is not allowed to continue for too long. If it runs unchecked,
the latent fingerprints can overdevelop and the chemical images of the ridges
will slowly grow wider until they overlap, obscuring vital detail.
Generation of CA fumes through controlled
heating
CA adhesives have a boiling point of approximately 120°F (50°C). With
increasing heat, cyanoacrylate decomposition products begin to appear at
temperatures above 250°F (121°C), and when the temperature exceeds 400°F
(204°C), hydrogen cyanide can be produced. It is therefore critical to
maintain a consistent, controlled heat throughout the development process.
The CApture Print System uses a heater, controlled by a digital controller.
The user-programmed controller maintains the set temperature between the
minimum of 120°F (50°C) and maximum of 350°F (177°C). A redundant
safety switch limits the heater temperature to a maximum of 350°F (177°C),
in the event of a controller malfunction.
Clear Chamber
The clear chamber is made out of durable, shatter-resistant polycarbonate. It
protects the heater/filter module when the unit is being transported, and
allows an unobstructed view of the evidence during the fuming process.
While the clear chamber is resistant to many chemicals, it is not resistant to
CA fumes, and it MUST be treated with either Rain-X® or Rain Block
TM
glass water repellent. Labconco has tested these two treatments, and found
they protect the clear chamber from CA fumes for up to 20 uses, if properly
applied, and the treatment is not disturbed. Always follow the treatment
manufacturer’s instructions when applying the treatment. Labconco has not
tested any other brands of glass treatment chemicals, and cannot recommend
their usage.
Two Stage Filter System
CA droplets and fumes are removed from the air in the clear chamber by a
two stage filtration system. The first stage of the filter cartridge is a polyester
loft particulate filter, having a Minimum Efficiency Reporting Value
(MERV) of 11, meaning it removes 65-79% of particles 1.0-3.0 microns in
size, and more than 85% of particles 3.0-10 microns in size. The second stage
of the filter is specially prepared granular activated carbon (GAC) that
adsorbs any gaseous CA as the air flows through the carbon bed. See
Appendix A for replacement part numbers. Using the recommended amount
of CA for proper development, the filter should last for a minimum of 100
fuming cycles (about 2 oz, or 57ml) before replacement.