Page 1
WATLOW
FIREROD®CARTRIDGE HEATERS
PROVIDE QUALITY
AND
ENGINEERING
EXPERTISE FOR YOUR
MOST DEMANDING
APPLICA TIONS
Page 2
Selecting cartridge heaters for
industrial applications should involve
more than just specifying temperature
and power requirements. Today’s users
benefit when their cartridge heater
supplier can provide:
•
Custom design for specific
applications
•
On-time delivery
•
A quality product for maximum
performance
•
Expert technical assistance
Watlow began answering these
cartridge heater needs in 1954, when
we designed and manufactured the
first swaged cartridge heater — the
FIREROD
®
—and revolutionized the
heating element industry.
We have continued to meet our
customer’s most challenging needs
with ongoing research and
technological improvements; solving
your toughest heating problems
through quality products, engineering
assistance and fast delivery.
..........................
FOUR QUESTIONS TO ASK
WHEN SELECTING YOUR
CARTRIDGE HEATER SUPPLIER
1.
2.
3.
4.
1. Does my cartridge heater supplier
provide a complete product and
service package?
2. Can I be sure I’ll get the products
I need, when I need them?
3. Is my cartridge heater supplier
building the best product possible?
4. Does my cartridge heater supplier
provide application assistance to
solve my heating problems?
Page 3
2.
1.
1. Does my cartridge
heater supplier provide
a complete product
and service package?
Watlow does.
•
Watlow is the only designer and
manufacturer to offer single source
thermal system capability with our
complete line of heaters, sensors and
controllers. Y ou are assured of Watlow
quality in each system component.
•
Continuous product testing is one
way we ensure quality at Watlow. Our
commitment to Total Quality and
World-Class Manufacturing programs
also leads to continual product
improvements for the FIREROD heater.
•
Prototype testing is often performed
for special customer applications, such
as unusual zoning, temperature
response and special life requirements.
Based on test results, Watlow can
recommend the proper operating
conditions to ensure long heater life
while providing optimal performance.
•
Watlow is a certified cartridge
heater supplier for many major
industrial manufacturers, having
passed stringent quality and
delivery tests.
•
Watlow’s worldwide sales and
distributor networks provide instant
access to expert technical advice,
application assistance and after-thesale service.
our customers send us their production
usage schedules and we ensure that
the required number of heaters are in
their plant, on time.
Watlow offers ship-to-stock delivery
as required by many vendor
certification programs. We’ve
established partnerships with a
number of customers requiring the
quality levels and reliability necessary
for these programs to succeed. This
has led to instituting specific in-line
inspection and test fixtures that
duplicate those used by our
customers.
Our in-house quality control teams
are well equipped to handle your
inspection needs.
Ordering a special or customdesigned cartridge heater doesn’t
mean you’ll have to wait months.
Because of our flexible World Class
Manufacturing “work cells” for the
FIREROD heater line, custom sizes can
often be designed and manufactured
in three to five working days.
2. Can I be sure I’ll get
the products I need
when I need them?
Watlow says yes.
Product availability is recognized as
industry’s single biggest problem in
maintaining demanding production
schedules.
Watlow offers several delivery
programs, such as Same Day
Shipment, Just-In-Time and Ship-ToStock, that allow you to reduce heater
inventories as well as costly downtime.
Watlow’s unique LA —or Lead
Adaptor —modification method
utilizes a patented lead connection
technique permitting same day
shipment on more than 150,000
configurations of stock FIREROD
heaters and lead combinations. Many
orders received by 4 p.m. local time
can be shipped same day.
The LA modification begins with a
standard FIREROD unit. The heater is
stocked on the shelf prior to lead
attachment. When the order is
received, the stock unit undergoes a
patented process and a specially
designed cap is swaged onto the
FIREROD heater to permanently
secure the leads.
Watlow has taken a leadership role
concerning your JIT programs. We
have special account coordinators
who can work closely with your
purchasing department to assure that
both release and ship dates are
closely monitored and met to avoid
costly shut downs or delays. Some of
SAME DAY SHIPMENT
...........................
JUST-IN-TIME DELIVERY
SHIP-TO-STOCK
EMERGENCY DELIVERY OPTION
(EDO)
Page 4
3.
While many cartridge heater
manufacturers now swage their
products, Watlow has developed its
own unique swaging process. This
assures consistent heater compaction
for longer heater life and uniform
temperatures. It also allows us to
manufacturer higher watt density
heaters.
Due to our tight manufacturing
controls, Watlow can provide the
smallest “no heat” section - on both
ends of the heater - of any cartridge
heater manufacturer. This is true of our
stock FIREROD heaters as well.
FIREROD cartridge heaters are
available in 1⁄8-inch to 1-inch
diameters and various lengths to
cover different applications. Watlow is
one of the only companies to offer
such a variety of specifications.
..........................
resistance, two factors that will reduce
lead wire failure and makes installation
easier.
•
The Pins: High-grade nickel pins
assure resistance to corrosion at high
temperatures and minimize the
chances of embrittlement.
Swaging was introduced to the
cartridge heater field in 1954 with
Watlow’s FIREROD heater. This
mechanical procedure reduces the
diameter of the heater by
compacting the unit, directly
improving heat transfer efficiency.
Swaging compacts the MgO
insulation, which increases its thermal
conductivity and, also, enhances its
dielectric strength.
Swaging also provides these
advantages:
•
Permits the resistance wire to
operate at lower temperatures, a
critical factor in longer heater life
•
Enables users to achieve process
temperatures faster
•
Provides more uniform heating to
the application
•
Reduces energy costs through
better heating efficiency
•
Makes the heater more durable
and more resistant to shock and
vibration
3. Is my cartridge
heater supplier
building the best
product possible?
Watlow is.
FIREROD cartridge heaters from
Watlow are built using only the finest
materials and construction methods,
and are backed with extensive quality
assurance programs. The FIREROD’s
advantages:
Watlow refuses to take shortcuts.
Y ears of testing have proven certain
construction materials and
manufacturing methods to yield the
best performance for FIREROD
cartridge heaters. Following are the
standard materials we use.
•
The Sheath: Our standard Incoloy
®
800 provides high temperature
resistance to oxidation and corrosion,
proving far superior to 304 stainless
steel alloys used by other
manufacturers.
•
The Insulation: We use only high
purity MgO, compacted to a carefully
predetermined and closely monitored
density. This assures high dielectric
strength and efficient, fast heat
transfer.
•
The Resistance Wire: Our nickelchromium wire of computercalculated gauge, length and
spacing is wound on a supporting
core and precisely centered for
uniform temperatures.
•
The Lead Wire: Watlow purchases
only the finest high temperature wire
available from certified suppliers. This
ensures wire flexibility and fray
PREMIUM MATERIALS
SWAGING
SMALLER “NO HEAT” SECTION
VARIOUS SPECIFICATIONS
AVAILABLE
Incoloy® is a registered trademark of Special Metals Corporation.
MgO Insulator
Seal
Lead Wires
Sheath
Pins
Nickel-Chrome
Resistance Wire
No Heat
Section
Page 5
Instead of adapting our
manufacturing processes to the
equipment available, Watlow designs
and builds its own manufacturing
machinery. As with our customized
swaging equipment, this allows more
consistent quality and tighter
tolerances. It also gives us more
freedom when modifying or
developing products.
We developed our own MgO fill
density equipment, calibrated to our
exact needs and designed so that
humidity, temperature or other factory
conditions will have no effect on the
MgO.
Watlow’s fill machines are
designed to ensure uniform fill
thickness which results in better
dielectric strength. Our electronic
winding machines, engineered and
manufactured in-house, provide
extremely consistent windings for
uniform temperatures.
Consistent quality is also achieved
through our own certified supplier
programs, which ensure that the
materials received meet our standards
every time. These “partnerships” with
suppliers also allow us to take
advantage of advances in materials
technology.
4.
4. Does my
cartridge heater
supplier provide
application
assistance to solve
my heating
problems?
Watlow does.
Technical assistance from your
cartridge heater supplier can be
crucial to the success of your heating
application. Premature heater failure
often occurs because your supplier
doesn’t ask the right questions about
your application, such as your
temperature and watt density
requirements, temperature sensing
and control systems, even factory
environment considerations.
At Watlow, our engineers can help
you avoid many of the common
causes of cartridge heater failure. We
have developed innovative design
options to combat the four most
common culprits:
•
Contamination
•
Corrosion
•
Overtemperature
•
Lead wire failure
CONSISTENT QUALITY
STANDARDS
...........................
Page 6
Teflon®is a registered trademark of
E.I. du Pont de Nemours & Company.
Hexoloy
®
is a registered trademark of Carborundum Company.
1. Overtemperature: The
discolored portion indicates
part of the heater was
operated in open air, rather
than being fully inserted in the
application.
2. Overtemperature: Resulted
in breakdown of insulation,
and caused element to short
to ground and burn a hole in
the sheath.
3. Contamination: External
view. Molten plastic has
solidified on the heater and
the leads.
4. Contamination: Internal
view. Notice that more
reaction has occurred in the
element winding area, where
temperatures are highest.
5. Overtemperature of heater
and leads: Red insulation boot
turned white, and became
frayed, which can cause the
lead wires to short.
CONTAMINATION
..........................
Table 1
Seal Type Maximum
Continuous
Operating
Temperature
Silicone Rubber 176°C (350°F)
Teflon
®
204°C (400°F)
High Temperature Epoxy 260°C (500°F)
Glass Hermetic 315°C (600°F)
Ceramic to Metal Hermetic 537°C (1000°F)
FIREROD HT (high temp.) 593°C (1100°F)
Mineral Insulated Leads 815°C (1500°F)
Table 2
Sheath Material Typical Applications
Incoloy
®
800 Excellent for most general
(FIREROD standard) applications
304SS Food and medical;
deionized water
Titanium For highly corrosive
atmospheres
Hexoloy
®
protection tubes Liquid metals
heating/melting
1.
2.
3.
4.
5.
CONTAMINATION
Contamination occurs when
foreign materials enter the heater’s
internal area and cause a breakdown
of the element or insulation materials.
The contaminants are usually organic
and cause either a gross electrical
shorting to ground or an accelerated
deterioration of the heater’s internal
elements and/or power leads.
Heaters that are subject to large
temperature swings or cycling are
most susceptible to ingesting harmful
contaminants. When a heater heats
up and cools down, it “breathes” air in
and out from its surroundings due to
the thermal expansion and
contraction of the air inside it.
As application temperatures
increase, many materials normally
considered inert can become quite
destructive. Among these are
lubrication oils, cleaning solvents, antiseize lubricants, plastics, fumes,
electrical tape adhesives, gases
emitted from over-temped lead wire,
potting compounds and moisture.
Page 7
...........................
Corrosion occurs when the heater’s
outer sheath deteriorates, allowing
contaminants to enter the heater.
Watlow offers several sheath materials
to protect the FIREROD from corroding
in various environments. (See Table 2).
For certain applications, such as
medical and aerospace, Watlow can
provide passivated or electropolished
heater sheaths.
&
AND CORROSION
6. 7.
FIREROD heaters can be designed
with special seals to resist contaminants.
Watlow offers several seal types
to handle various application
temperatures. (See Table 1).
It is important to realize that the
seal or lead end of the heater will not
exceed the maximum operating
temperature of the seal material.
This can be accomplished in one of
two ways.
One way is to allow enough natural
or forced air convection to cool the
area. In other cases, it may be
necessary to specify a length of
no-heat zone between the heated
and the sealed areas of the heater.
Smaller diameter heaters drop in
temperature along a no-heat zone at a
faster rate than larger diameters. By
using Graph A, a good estimate for noheat zone length can be interpolated
for most temperature, seal and heater
diameter combinations.
Stored heaters can be protected
by keeping the heaters in sealed
containers or plastic bags.
6. Corrosion: The sheath deteriorated to
the extent that liquid entered the heater.
During subsequent heating cycles the
weakened sheath split open due to
pressure build-up.
7. Scale build-up on sheath:
Overtemperature occurred because
scale acts as an insulator, causing the
heater to compensate by operating at
temperatures much too high.
CORROSION
982°C
(1800°F)
871°C
(1600°F)
760°C
(1400°F)
649°C
(1200°F)
537°C
(1000°F)
426°C
(800°F)
315°C
(600°F)
204°C
(400°F)
93°C
(200°F)
0
0.25 in. FIREROD
0.5 in.
1 in. 1.5 in.
0.5 in. FIREROD
2 in.
0.75 in. FIREROD
2.5 in.
3 in.
3.5 in.
4 in.
Page 8
..........................
Color V ersus Temperature
The chart was created by recreating the colors of Incoloy® sheathed FIRERODs at specific temperatures. Several factors may
affect the color, but the chart is a handy reference of color vs. temperature for most metal objects. The power levels
indicated were calculated using the Stefan-Boltzman equation for a blackbody source at the temperatures listed.
A heater that is forced to operate
beyond its maximum operating
temperature is destined for premature
failure. Extreme overtemperature
conditions will cause the heater’s
internal conductors to melt. Less
severe overtemperature conditions will
accelerate a heater’s normal “aging”
process. In fact, operating a heater
37°C (100°F) beyond its maximum
recommended temperature can
reduce heater life by as much as
two-thirds.
Watlow designers optimize the
internal construction of your FIREROD
based on the wattage and operating
temperature you specify. Y et certain
conditions can cause the heater to
overtemp.
Overtemperature failure frequently
occurs when a heater is placed in a
hole that is too large, impeding heat
transfer from the heater to the part.
Watlow’s hole fit
graphs (B and
C) depict the
importance of
hole fit, and how
dramatically it
affects the temperature of the
heater’s internal components.
Allowing part of the heater’s heated
section to operate in open air can
cause the exposed section to rise
significantly in temperature, while the
part immersed or inserted into the
application is kept at the desired
temperature.
The solution is to be sure the heated
section is fully inserted into your heated
part or liquid.
A loose fit causes cartridge heaters to operate at temperatures that are much higher
than the part being heated. This is even more dramatic at higher watt densities. Using
a tighter hole fit and lowering the watt density will keep the heater’s internal
temperature low, prolonging life significantly.
Fit = I.D. Hole - O.D. FIREROD
This graph will help you
determine the maximum
allowable hole fit for your
application. Notice that
both the heated part
maximum temperature and
the surface watt density of
the heater affect the
recommended hole fit.
OVERTEMPERATURE OF THE HEATER
HOLE FIT
EXPOSED HEATER SECTION
1204°C (2200°F)
27.29 W/cm
2
(176.1 W/in2)
1093°C (2000°F)
19.96 W/cm2 (128.8 W/in2)
982°C (1800°F)
14.22 W/cm2 (91.8 W/in2)
NOTE: Maximum part temperature 760°C (1400°F), maximum watt density 69 W/cm2 (400 W/in2).
Hole Fit
Graph B: How Hole Fit & Watt Density Can Affect Internal Heater Temperature
Heater Operating
Temperature
(in block heated to 537°C (1000°F)
1204°C
(2200°F)
1093°C
(2000°F)
982°C
(1800°F)
871°C
(1600°F)
760°C
(1400°F)
649°C
(1200°F)
0.006
0.009
0.010
0.012
Hole Fit (inches)
0.015
0.0195
0.018 0.021
0.100
0.090
0.080
0.070
0.060
0.050
0.040
0.030
0.027
0.020
0.013
0.010
0.009
0.008
0.007
0.006
0.005
0.004
0.003
0.002
0.001
For stainless steel, enter
the graph with a fit 0.0015
larger than actual.
For aluminum and brass
enter the graph with a
temperature 37°C (100°F)
above actual temperature
760°C (1400°F)
649°C (1200°F)
537°C (1000°F)
426°C (800°F)
315°C (600°F)
204°C (400°F)
93°C (200°F)
Page 9
...........................
Poor temperature sensor location is
another common cause of
overtemperature heater failure. If the
controlling thermocouple is placed on
the edge of a heated part that runs
cooler due to “end effects” of heat
losses to atmosphere, the center
portions of the heated part can run
significantly higher in temperature,
forcing the heater to operate well
over its maximum recommended
temperature. The solution is to place
the temperature sensor in the hottest
part of the application.
When heating fluids or gases in
chambers, the process becomes
hotter as it flows through the chamber.
Thermocouples at the cooler end of
the chamber will be unable to
properly control heaters at the hot
end, causing early heater failure.
One solution is to relocate the
thermocouples to the hot end, or to
use lower watt density heaters at
that end.
Watlow can also design your
FIREROD heater with an internal
thermocouple to provide accurate
temperature readings. This is especially
beneficial for extremely sensitive,
zoned or uniform temperature
applications. Thermocouples can be
located at the disc end of the heater
or anywhere along the heater length.
Also, thermostats are available as a
high-limit temperature control.
Surprisingly, overtemperature failure
can occur in some low temperature
applications such as heating water.
Conventional thinking suggests that a
heater immersed in liquid should never
greatly exceed the boiling
temperature of that liquid. But this isn’t
always the case. (See Graph D).
Placing power leads in a high
temperature environment can lead to
premature heater failure if the leads
aren’t properly rated for the
application. The binders in the lead
wire insulation will bake out and the
insulation becomes brittle. Any
amount of flexing after this usually
causes electrical shorting between the
lead wire conductors or a grounded
surface.
To combat this problem, W atlow
offers six types of insulation for lead
wire (see Table 3.)
Vibration is a frequent cause of lead
wire failure. Over-flexing can be
prevented by adjusting the lead wires
to withstand high vibration, as in a
moving or cycling platen or mold die.
To protect the leads, isolate any
relative movement of the heater and
leads by adding strain reliefs that
anchor back to the platen or heated
part. Y ou can also allow extra lead
length for flexing.
Watlow provides several lead wire
types that are ideal for applications
requiring abrasion assistance. These
include flexible stainless steel overbraid
and flexible metal conduit.
Graph D shows how water’s ability to
accept heat from a FIREROD heater
changes with watt density. A good rule of
thumb for water is to add 1˚F for every W/in
2
of heater surface to the boiling point of
water. (Example: On a 200 W/in2heater,
internal operating temperature =
200 W/in2+ 212˚ = 412˚F).
Heat flow between the heater sheath and
liquid can also be impeded by the buildup
of mineral deposits on the heater sheath.
The heat won’t be able to leave the heater,
causing its internal temperature to rise
dramatically.
SENSOR LOCATION
LOW TEMPERATURE
APPLICATIONS
LEAD WIRE FAILURE
OVERTEMPERATURE OVER-FLEXING
ABRASION
871°C (1600°F)
9.81 W/cm2 (63.3 W/in2)
760°C (1400°F)
6.52 W/cm2 (42.1 W/in2)
649°C (1200°F)
4.13 W/cm2 (26.7 W/in2)
Table 3
Insulation Material Maximum
Continuous
Operating
Temperature
Neoprene 93°C (200°F)
Silicone 176°C (350°F
Teflon
®
204°C (400°F)
Fiberglass/Silicone (GGS)
249°C (480°F)
Mica/Fiberglass/
Teflon®(MGT) 449°C (840°F)
Ceramic Beads 649°C (1200°F)
Mineral Insulated Leads 815°C (1500°F)
426°C
(800°F)
315°C
(600°F)
204°C
(400°F)
93°C
(200°F)
0
Sheath Watt Density (5/8 in. diameter FIREROD in water boiled in ambient conditions)
Page 10
✓
A gas analysis system required a heat
source capable of handling
temperatures above 649°C (1200°F)
and to provide heat to the analyzer
head from distances of up to 10 feet.
A 1⁄4-inch diameter, 10 -foot long
FIREROD heater was designed with a
unique heated zone that included an
internal thermocouple and a long noheat section.
A manufacturer of blood warming
equipment required a heat source
with an integral high limit cutoff device
as a protective measure for the
system. A FIREROD heater was
designed to meet UL®specifications for
medical equipment. An internal
thermostat provided the secondary
high limit necessary to prevent the
plastic reservoir from melting.
A food processing plant required
moisture-proof cartridge heaters that
could operate at temperatures higher
than Teflon
®
204°C (400°F) and potted
seals 60°C to 260°C (140°F to 500°F).
To eliminate the extra steps required
to protect heater leads from moisture
contamination during high-pressure
hose washdown, Watlow recommended the FIREROD with M.I. lead
temperature capability to 815°C
(1500°F).
A food packaging machine
manufacturer needed to apply heat
to an adhesive-backed paper lid and
seal it onto the mouth of a plastic
container. By concentrating the heat
only around the edge of the
container, none of the dairy product
inside the container would be
affected by the sealing process.
SOLUTION TO COMPLEX
HEATING PROBLEM
SOLUTION TO COMPLEX
MEDICAL STANDARD PROBLEM
SOLUTION TO COMPLEX
CONTAMINATION PROBLEM
SOLUTION TO RESPONSE
TIME PROBLEM
WATLOW SOLUTIONS TO
YOUR HEATING PROBLEMS
Watlow specializes in solving demanding heater
applications through customized engineering.
Our experience is reflected in our design of over
250,000 different FIREROD heaters for such
industries as plastics processing, packaging,
medical equipment, aerospace, scientific
instruments, semiconductor, foodservice and
nuclear power generation.
..........................
UL®is a registered trademark of Underwriter’s Laboratories, Inc.
Page 11
An additional problem with the
application involved the high
throughput required for the machine,
making the duration of heater contact
less than one second. A FIREROD
heater was designed with a centerless
ground sheath for good hole fit and
heat transfer, and a special fill material
in the heater to greatly increase the
heater’s thermal conductivity.
A small, high watt density FIREROD
cartridge heater was designed to
provide freeze protection on a radar
guidance system used on missiles. The
application had space limitations, but
more importantly, the heat source had
to meet pages of military standards.
These specifications covered
everything from the type of nickel wire
to be used to complex test criteria.
A custom manufacturer of titanium
expanders for the aircraft/aerospace
industry required heat in order to form
thin walled titanium tubing into missile
nose cones. The application required
a uniform die temperature operating
at 760°C (1400°F). Multiple HT (high
temperature) FIREROD heaters with
zoned wattage were chosen because
of the die and the even higher internal
temperatures. Also, a special HT seal
reduced the amount of oxidation and
corrosion of the resistance wire thus
prolonging heater life.
Uniform temperature profile is critical
for the large sealing bars of vertical
and horizontal wrapping machines.
SOLUTION TO COMPLEX
MILITARY
STANDARD PROBLEM
SOLUTION TO HIGH TEMPERATURE
REQUIREMENT PROBLEM
SOLUTION TO TEMPERATURE
UNIFORMITY PROBLEM
Watlow conducted testing to
determine the proper heat zoning
needed to compensate for heat losses
at the ends and at the machinery
clamps. A FIREROD cartridge heater
with special distributed wattage was
designed, providing the extremely
tight profiles required by the
packaging equipment manufacturer.
A commercial sign producer needed
a means to apply heat to an
extremely small stylus used to cut vinyl.
Watlow engineers solved the
application using a 1⁄8-inch diameter
FIREROD with an internal
thermocouple for temperature
control.
A high-speed photographic film
processor required a heat source to
maintain stringent developer
temperatures, despite the highly
corrosive nature of these solutions. In
addition, the system design provided
limited space. Watlow engineering
designed a FIREROD heater with a
passivated 316 stainless steel sheath
and a unique flanged mounting
method.
A FIREROD heater with its high watt
density capabilities was designed for a
compact, mobile hyper/hypothermia
system. The heater was required to
meet UL®specifications for low current
leakage under the guidelines for
medical equipment.
SOLUTION TO LOW CURRENT
LEAKAGE SPECIFICATIONS
...........................
SOLUTION TO SPACE
LIMITATION PROBLEM
SOLUTION TO CORROSIVE
ENVIRONMENT PROBLEM
Page 12
12001 Lackland Road • St. Louis, Missouri 63146 USA
Phone: 314-878-4600 • FAX: 314-878-6814
e-mail: info@watlow.com • www.watlow.com
WATLOW
Worldwide Business
Centers
STL-FR-0706
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Sales Offices
Australia +61-3-9335-6449
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Sales Office
Mexico +52-442-217-6235
Watlow Products and Technical Support Delivered Worldwide
North American Technical
Support & Sales Offices
Your Authorized Watlow Distributor is:
To be automatically connected to
the sales office nearest you call:
1-800-WATLOW2
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