|This specially formulated heat transfer fluid developed by
BPI has been proven to be the best heating medium available. It heats quickly and evenly,
maintains the high temperatures needed for your dyes, and is non-toxic. It helps preserve
the interior of your base tank and protects your heating element as its evaporation factor
is nil. It is unwise to make any substitutions, (such as anti-freeze) which may corrode,
evaporate quickly, or release toxic vapors.
Heat transfer fluid should be changed when
contaminated. Dye solution or chemicals, when mixed with heat transfer fluid causes boiling and
hot spots within the transfer fluid. This may result in dislodging a dye tank, splashing a
dye, or boiling up from the base tank (liner pan).
A crackling or popping sound may be the result of water, chemistry or dye solution being
mixed with the heat transfer fluid. For minor spills, idling your system at 130°F. for several
hours may evaporate the contaminant sufficiently to eliminate the boiling. Of course, it
will not evaporate the pigment from the dye itself, but just the water with which it is
mixed. Another sign of heavily contaminated heat transfer fluid is an obnoxious, irritating odor.
When in doubt, change the heat transfer fluid.
One way to remove heat transfer fluid is to dip
out the fluid as much as possible; another is to use a siphon. Use paper towels to absorb
the residue, and wash base with water if needed. This is also a good time to check your
The silver protective coating which was on your element before will have disappeared after
initial use. This was only a protective coating to help prevent damage due to storing
prior to installation in your machine. Run your fingers over the heating element. It
should be smooth to the touch. If you feel any roughness due to encrusted dye, remove it
by gently cleaning with a nylon or plastic cleaner, taking care not to scratch the
This inspection is important to you, as such buildups on your element will eventually
interfere with proper heating by acting as a barrier, concentrating intense heat within
the element, burning it out. It is also a good time to check for bulges on the element
which indicate weakness.
In recent advertisements, some manufacturers
are claiming that using water as a heat transfer medium is the best way to heat dyes in a
tinting system. This is not so, and needs to be addressed so that proper lens coloring can
be achieved, and proper health and safety can be maintained in the optical laboratory. To
be effective, the heat transfer fluid temperature should be higher than the dye solution
inside the dye tank. Tests conducted at BPI have shown that as the dye solution nears
boiling, the temperature differential between the heating fluid and the dye tank should be
optimized at near 40°F. (To maintain a 205°F dye tank).
This differential requires the heat transfer solution to be maintained at about 245°F.
This temperature differential cannot be achieved using water open to atmospheric pressure
as a heat transfer medium. The maximum temperature of water at boil is 212°F (100°C),
thus making it difficult to achieve the proper dye tank temperature to assure proper
color, fade resistance, and color stability.
"Water is an extremely poor
a heat transfer medium for lens tinting"
Dr. William Moore Ph.D. BPI Research Physicist
BPI heat transfer fluid Has 7,600 Times Less
Evaporation Than Water
Water Is 320% Less Effective As A Transfer
Medium Than BPI heat transfer fluid
Using Water As A Heat Transfer Fluid Can
Increase Electricity Costs More Than 500%
Six Disadvantages Of Using Water As A
Requires up to 500% more electricity to
color lenses at 205°F.
Extra heat and vapor are broadcast
throughout the lab, requiring additional air conditioning or ventilation to maintain
stable temperature and humidity.
Water must be constantly added to the system
to maintain the proper level of fluid so that the heating element will not burn out.
Dye and other chemicals will oxidize the
heating element and fluid container. This causes an acid solution to be formed that causes
holes and corrosion in the heating chamber.
Water may conduct electricity to the dye
solution if the heating element burns out while the tinting system is in use. This could
cause a shock if the system is not properly grounded and fused.
Since proper temperature is difficult to
achieve, colors will fade and are less stable. Especially if the lenses are to be AR
coated. The highest dye temperature possible is desirable for tinted AR coated lenses.
Heating water requires large amounts of energy
compared to other fluids. It takes about 80 calories to heat a gram of water from room
temperature to boiling. Once it is boiling, however, it takes 540 calories for each gram
of water you boil away! Extra heat is released into the room and may require additional
air conditioning and ventilation to reduce temperature and humidity. A good heat transfer
medium expands when heated, becomes less dense, and rises up to heat the dye tanks in the
tinting system. (Convection)