User Manual

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Frequently Asked Questions
Refer to these FAQs to learn more about Minco’s heater offerings
Thermofoil Heaters
What is the correct voltage for this heater?
Standard heaters are specified by resistance, not voltage. This
lets you operate them at different power levels. In selecting a
heater model you should consider the size, resistance, operating
temperature, total wattage and watt density (watts/in² or watts/
cm²) for your application. The watt density rather than the total
wattage determines the maximum applied voltage. Maximum
watt density depends on the insulation type, mounting method
and operating temperature. Graphs of these limits are included
in each product section of this bulletin.
Minco standard and stock wire-wound silicone rubber heaters
are listed with a recommended voltage based on typical
ambient conditions and operation. It is often possible to exceed
the listed limits. Contact Minco for more information if your
application requires more power than the standard limits allow.
Can a Thermofoil heater be used suspended in
air?
Because the mass of a Thermofoil heater is very small they are
generally not suitable for heating in air. Thermofoil heaters
operate best when mounted to an object that can be heated by
conduction rather than convection or radiation.
What are the dimensions of the lead attachment
area for standard heaters?
The size of the non-heated lead attachment area varies based
on the leadwire size, insulation material, lead exit location and
heater dimensions. For a polyimide (e.g. Kapton™) insulated
heater these range from 0.25 × 0.30” (6.35 x 7.62mm) to 0.5 ×
0.8” (12.7 x 20.32mm) for sizes AWG 30 to AWG 20. Describe
your space limitations when specifying a custom design. Leads
can be attached to a non-heated tab outside the body of the
heater.
What is the temperature coefficient of resistance
(TCR) for Minco heater elements?
Standard etched element heaters (except resistance options
listed under the “NiFe” and “Ni” columns) use very low TCR foil
materials. These can be considered to have a flat resistance to
temperature relation for most applications.
Etched element heaters under the “NiFe”and “Ni”columns use
either nickel (0.00672 Ω/Ω/°C) or nickel-iron (0.00519 Ω/Ω/°C)
foil. Thermal-Clear heaters use copper wire (0.00427 Ω/Ω/°C),
nickel wire (0.00672 Ω/Ω/°C), or nickel-iron wire (0.00519
Ω/Ω/°C). These higher TCR models are not self-limiting but can
be used with Minco’s Heaterstat controller where the heater
element performs the sensor function.
Can I immerse these heaters in water or other
liquids?
Generally the answer is no. The materials used in Polyimide
insulated Thermofoil heaters are waterproof, but edges are not
sufficiently sealed for immersion. Custom designs (including all
PTFE heaters) can include increased border areas and sealed
leadwire connections that make these heaters immersible in
water. Silicone rubber insulated heaters require RTV cement
or similar materials along all exposed edges and leadwire
attachment areas for immersion in water.
If your application requires contact with other liquids contact
Access: Minco Sales and Support with details and we can
helpdesign a solution.
Can I trim a Thermofoil heater to the size and
shape I need after I’ve received it?
No- Thermofoil heaters cannot be cut or trimmed. The
element conductor covers the entire area to maximize the
heat spreading effect of the etched-foil design. Cutting into
this would create an electrically open circuit and expose the
electrically live element.
When would I specify aluminum foil backing for a
heater?
Foil helps to spread heat between heater strands, improves
adhesion of PSA, and makes polyimide less springy for better
conformance to curves. It increases the temperature and watt
density ratings of polyimide heaters with PSA. For silicone
rubber heaters, foil with acrylic PSA is less expensive than #12
PSA applied directly to the rubber.
SmartHeat SLT Heaters
Is SmartHeat SLT most similar to a resistor,
capacitor, or inductor?
SmartHeat is a resistive technology. What separates this product
from traditional resistive technologies is a unique positive
temperature coefficient (PTC), which establishes a strong,
exponential relationship between resistance and temperature.
This creates a self-tuning effect that makes SmartHeat suitable
for a variety of warming applications.