An instructional blog about specialized electric heating elements and vacuum feedthroughs for the OEM, analytical, semiconductor, aerospace, pharmaceutical, chemical, water, environmental, food processing, and alternative energy markets. Please feel free to contact us at (510) 274-1990 with any questions. BCEmfg.com
How ISO 9001 Protects BCE’s Leadership in Electric Heaters and Vacuum Feedthroughs
Mini Clean Flow Heater for Harsh Environments
- Temperature outlet needed to be 100⁰C
- Perpendicular configuration, with locking fittings
- Body must pass Helium Leak rate of 1 x 10-7 cc/sec He
- Pressure test of 50PSI
- Ability to place heater in a series flow configuration if necessary
- Thermocouple for additional temperature measurement
- 400 Watt, 120 Volt
- All wetted surfaces must be 304 or 316 Stainless Steel L (low carbon)
Experienced Electric Heating Element Designers Speed Development Time and Save Money in OEM Product Development
Technology advances rapidly, and findings in material science, medicine, pharmacology, biology, and semiconductors occur daily. These advancements in technology open the door for performance improvements leading to new treatments, medications, materials, and processes. Original equipment manufacturers (OEM's) of analytical, semiconductor, biomedical, life-science, and aerospace equipment continually design new equipment to apply and leverage these new discoveries.
Experienced custom electric heater designers provide many essential benefits throughout the product development cycle. For instance:
- Front-end, practical design review to optimize manufacturability.
- Timely prototype development.
- Strong alliances with vendors.
- Single source responsibility.
- Testing, calibration, and QC.
- Inventory management.
- Value-added assembly.
The heater manufacturer partner provides:
- Critical guidance in material selection.
- Power requirements under load.
- Temperature vs. time data.
- Watt density optimization.
- Packaging advice.
Their help provides high performance, precise fit, and extended heater life.
The pressure to produce new devices that offer greater efficiencies, compactness, and production is always present. Each item in the precedent design undergoes scrutiny and transitions to a contemporary fit, form, or function. New components are needed to meet the new design requirements. By choosing an experienced custom electric heating element design partner, the OEM gets the precision they need, plus scores of other benefits derived from the heater vendor's tacit knowledge and past experiences.
HK 300mm Compressed Heater Chuck
BACKGROUND
To reduce the overall cost for an existing application, BCE developed a 300mm aluminum heater chuck that is un-brazed utilizing the compression of two plates with countersink set screws. The heater surface specs were 0.003” flatness at a 0.005” parallelism. Using a 208-volt power supply at 9.7ohm, start @ 25°C temperature and ramped from 100°C to 465°C in 23 minutes.
SCOPE
Aluminum Heater Chuck needed to satisfy the following:
- Achieve temperature up to 435°C @ +/- 2% or better
- Internal element must be able to withstand temperatures up to 600°C
- Anodized surface for electrical isolation
- 208 Volt, 9.7 Ohm, 4,460 Watt (+5% / - 10%)
- Thermocouple bore hole to be placed at the center (variable)
- 4 point temperature profile on the top surface of the heater
- Used an infrared sensor for each 4 point locations
- FINISH: Hard coat anodize per MIL-A-8625F, Type 3 Class1 Hard-coat thickness
OUTCOME
BCE produced a highly effective high 300mm heater with exceptional uniformity better than the proposed 435°C (+/-2%). After the initial ramp, the heater maintained 435°C (+/- 1%) as per the chart below (Temp profile #5).
Industrial and OEM Electric Heating Elements
There are many places where electric heaters comes in touch with our lives each day. They are used to keep living spaces warm for human beings and animals (commonly referred to as "comfort heating"). Electric heating elements are found in common home appliances such as toasters, stoves, and hair dryers. But beyond the day-to-day consumer applications, electric heaters are also ubiquitous in industry. Industrial heating elements are critically important to many manufacturing processes, wether as an equipment component (OEM heaters), or directly used in the the processing of raw materials (industrial electric heaters).
In industry, electric heating elements are commonly used in the manufacture of electronics, semiconductors, medical devices, food equipment, plastics equipment, pharmaceuticals, glass, ceramics, primary metals, aerospace equipment, and HVAC equipment. While the industries that use electric heaters vary widely, the application of electric heaters narrows to the heating of flowing fluids (which include gases and air) or the heating of a solid metallic, or non-metallic, workpiece.
Types of Electric Heaters Used in Industry and Original Equipment Manufacturing
While the modes of transferring heat from on body to another will always be conduction, convection, or radiation, the mechanical and physical properties of industrial heaters change dramatically, depending on the media being heated, the physical and limitations of the application, and the application's temperature requirements. The following are the most common types of industrial and OEM heating elements used.
Tubular Heating Elements
Tubular elements are a common form of electric heater. Essentially a metal tube with resistance wire and electrical insulation inside, tubular elements can be configured into almost uncountable shapes and sizes.Cartridge Heating Elements
Cartridge heaters provide localized heat to restricted work areas requiring close thermal control. Dies, platens and a variety of other types of processing equipment are efficiently heated.Flexible Heating Elements
Flexible Heaters are made from a variety of materials such as Silicone rubber, Kapton, Mylar, or Neoprene and have etched foil or wirewound resistance elements. Fast responding with excellent heating profiles, these heaters solve many tough equipment heating challenges. Custom shapes and terminations are designed to suit. Rapid prototype service available.Ceramic Heating Elements
Composed of high temperature materials such as alumina ceramic substrates. The metal heating resistance element is thickfilm technology or wire.Thick Film Heating Elements
A process of depositing a resistor “trace” of tungsten paste on top of a ceramic part in a process very similar to screen printing. The deposition process allows for close control of thickness and width of the resistor, thus accurately controlling the conductor resistance, wattage, watt density, and uniformity of the heated part.Mini Clean Flow - Stream Heater
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| Mini Clean Flow Heater |
SCOPE
The Mini Clean Flow - Stream heater needed to satisfy the following:
- Outlet of temperature of 75 °C (± 2 °C) to eliminate bacteria
- Ability to place heater in a series flow configuration if necessary
- Built in thermocouple for accurate temperature measurement
- 185 Watt, 120 Volt
- All wetted surfaces must be 304 Stainless Steel
- Watt density below 30 WSI to avoid damage to the fluid or system
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| Test Results - Click for larger view. |
For more information, contact BCE by calling 510-274-1990 or visit their web site at https://bcemfg.com.
Important Safety and Performance Precautions When Using Electric Heating Elements
The safety and performance of electric heating elements is dependent upon the user's proper handling, installation, control, application, and maintenance. While it is impossible to anticipate all the operating conditions for electric heaters, the following items are universal precautions that must be considered in every situation.Electric heater element handling, installation, application, and maintenance precautions:
- Always have a qualified person install the heating element in accordance with the National Electrical Code and/or local codes.
- Always use extension wire rated for the current, voltage, and exposure temperatures suitable for the application.
- Always use the proper environmentally rated electrical connection and housing for the type of service the heater will see.
- Use temperature controlling and/or limiting devices with electric heaters.
- Use ground fault protection where required.
- Do not apply higher voltages than the marking on the heater indicates.
- Do not operate heaters in thermally insulated conditions where sheath temperatures may exceed the recommended maximum.
- Do not expose heaters to conditions, substances or contaminants that can damage, change, or destroy the integrity of the heater's sheath or electrical insulation.
- Heaters by their nature can absorb moisture which can cause high leakage current. A megohm test to the manufacturers specification should be performed to ensure moisture levels are within acceptable standards.
- Do not apply heaters with operating sheath temperatures that exceed the safe exposure temperature of the process media.
Cartridge Heater Design
First, it's important to understand a very basic concept when applying electric heating elements. All electric heating elements need to move the heat away from the resistance wire into the surrounding media. This is done through conduction, convection, and radiation. Preventing resistance wires from getting too hot is the goal.
The difference comes down to internal design.
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| Low watt density cartridge heater. |
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| High watt density cartridge heater. |
High watt density cartridge heaters, capable of higher operating temperatures and long life include a different internal design, incorporating a swaging process and great care to resistance wire placement. High watt density heaters have very precisely wound nichrome resistance wire around the ceramic bobbin, and then, with exact centering and very tight tolerances, vibrate MgO into the metal tube surrounding the bobbin/wire core. Once the MgO is added, the heater goes through a swaging process that reduces the inner diameter of the metal tube. The result is compacted magnesium oxide with rock-like properties and much better thermal conduction from resistance wire to external heater sheath.
Both styles of cartridge heaters have their value and proper application. Using low watt density cartridge heaters on a simple applications like glue pots is fine, and will yield good life and performance. On the other hand, high temperature applications such as plastic injection mold machines require the higher performance and extended life that only a swaged heater will provide.
Contact BCE for more information on electric heating elements. Visit https://www.belilove.com or call (510) 274-1990.
Rapid Response Electric Heaters Designed for Clean Gases and Liquids
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| Mini Clean Flow Heater |
The use of standard screw plug immersions heaters, screwed into a stainless steel welded vessels (known as circulation heaters) are almost always a misapplication for these unique requirements. Circulation heaters create more problems due to leaks, material compatibility, poor controllability, and bulky size.
BCE, a northern Californian manufacturer of custom heating elements offers it's Mini Clean Flow Heater specifically for these applications. These heaters are designed for heating "clean" liquids and gases normally found in fuel cell, bio-med, laboratory, food, semiconductor and pharmaceutical applications.
The Mini Clean Flow Heater operates in a liquid or gas stream providing very fast response times and accurate control capability.
The heating elements in the Mini Clean Flow Heater are isolated electrically from the process media, protecting them from contaminants and providing long life.
Summary:
- Designed for heating of clean gases or liquids
- Gas flow passes over an enclosed heated body; not exposed to resistive elements (Nichrome)
- All parts exposed to gas flow are constructed of 304 stainless (other material available)
- High temperatures
- Custom wattages, voltages, inlet and outlet fittings (NPT, SAE, BSP &VCR) are available.
- Made in U.S.A.
For more information, visit http://heater.belilove.com
Why Cartridge Heaters Fail
Improper Fit
The most common cause of cartridge heater failure is an improper fit in the hole into which it is inserted. If the heater cannot dissipate the heat being generated and produced by contact with the sheath, the temperature inside the heater will continue to rise until the heater fails.
Moisture and/or Impurities
The MGO used in cartridge heaters is hydroscopic. Every time power to electric heaters is eliminated, an internal vacuum occurs which draws in air from the surrounding area. If moisture or impurities (oil, gas, etc.) are present, they can be drawn in to the heater, and cause a short circuit resulting in a heater failure.
Watt Density is Too High
If the watts/square inch is excessive, the heater will not be able to dissipate the heat and the heater will fail.
Incorrect Voltage Applied
The wattage of any electric heater varies as the square of the voltage. If a 120 Volt heater is powered on 240 Volts, the wattage will be 4 times greater than that for the same 120 Volt heater. Under normal conditions, this may result in heater failure.
Frequent Temperature Cycling
Rapid cycling of heaters from very low to very high temperatures shortens their life considerably.
- Cartridge heaters
- Immersion heaters - ideally suited for heating various liquids
- Air process heaters - for providing hot air and gas up to 1,400 degrees
- Stainless steel strip and thin strip heaters in various sizes
- Self-contained one-piece assembly coil and rope heaters
- Tubular and finned tubular heaters - specially built to resist impact, vibration corrosion and temperature extremes
- Band heaters for a multitude of applications
- Ceramic and crankcase heaters
Heaters for Process Air and Gases
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| Examples of process air heaters Courtesy Hotwatt |
The primay selection criteria for a process air heating unit should be the heating capacity or wattage. Determine the maximum flow rate, inlet and outlet temperatures, then apply a simple formula from the document included below to find the minimum watt rating for a heating unit. Outlet temperatures can range to 1000°F (540°C) and flow rates to 200 scfm. Custom units can accommodate applications beyond those limits.
The outlet temperature can be controlled in a number of ways. One is to regulate the power applied to the heater. This would be applicable to a process that required a constant or minimum air flow rate. If the flow rate can be varied, another method of temperature control is available. Maintaining constant power to the heater and varying the air flow rate can serve as a means of controlling the output temperature.
Various connection sizes and fittings can be included in the heater assembly design to accommodate its incorporation into a process equipment train. Share your process heating requirements and challenges with experienced application engineers, combining your own process knowledge with their product application expertise to develop effective solutions.
Flanged and Screw Plug Electric Heating Assemblies for Industrial Applications
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| Flanged Tubular Electric Heater Assembly Hotwatt |
Tubular elements are a common form of electric heater. Essentially a metal tube with resistance wire and electrical insulation inside, tubular elements can be configured into almost uncountable shapes and sizes. Manufacturers typically offer a range of standard sizes and ratings, but that should never deter you from making contact to discuss your ideas for a custom arrangement.
Two mounting schemes that are readily used on tanks or other vessels are the screw plug and flanged heater assemblies. In each case, tubular heaters are bent in a "U" shape and fitted into either a pipe flange or a threaded plug. A junction box encloses the electrical terminations for the heating elements, providing a single ended assembly that can be easily mounted to an industrial standard mechanical connection. These assemblies are useful for tank or vessel OEMs that wish to provide a fluid heating option to their customers.
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| Examples of Screw Plug Electric Heaters Hotwatt |
Electric heat enables a properly configured controller to proportion heat into a subject fluid across a wide range, from very small packets that could be fractional percentages of full capacity to the fully available output of the heater. The units are compact, rugged, and can be configured to accommodate a broad array of industrial environments and applications.
Selecting or specifying a unit is uncomplicated. Determine the amount of heating capacity needed, then select the assembly mounting type (flange, screw plug, or other). Select an element sheath material that is compatible with the process media and a termination enclosure that suits the surrounding environment. Application assistance is available from product specialists who are well versed in the available options and can help you specify an assembly that provides excellent performance and an extended service life.
Hotwatt Electric Heating Elements for OEM, Laboratory, and Industrial Applications
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| Hotwatt Electric Heating Elements |
Contact BCE for more information at (510) 274-1990 or visit http://www.belilove.com.
Electric Heaters 101: Get the Heat Out of the Heater
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| Internal view of swaged cartridge heater. |
At the heart of most resistance type electric heaters is a nichrome alloy wire, or ribbon, referred to as the heating "element". It acts as a resistor to the electrical current and gives off heat. With sheathed heaters, the heating element is then wrapped in some sort of electric insulating material such as mica or magnesium oxide (MgO), and then encased in a metallic sheath. Unfortunately, both the electric insulator and the metallic sheath act as heat insulators to some degree, which cause the nichrome wire to get very hot. Nichrome wire has a melting point of 1400 deg. C (about 2500 degrees F). While this sounds high, the wires and ribbons can easily exceed these temperatures in normal operation when not allowed to adequately conduct heat.
Very often electric heater failure can be directly attributed to poor conductivity between the heating element and the process medium. Whether it be a cartridge, strip, band, duct or immersion heater the principle is the same - lower resistance wire temperatures equal longer heater life.
When applying cartridge heaters, special care has to be taken to the bore tolerance of the hole where the heater is inserted. The tighter the bore tolerance, the more efficiently the high internal wire temperatures are conducted away. Tolerances of several thousandths of an inch can change the life expectancy of a cartridge heater significantly.
Strip and band heaters require tight, full surface area clamping to maximize life and performance, while duct heaters and immersion heaters require circulation to transfer heat away from the element, and keeping resistance wire temperature within reasonable operating limits.
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| Internal view of band & strip heater. |
Any situation where the heater is exposed to a stagnant air gap (or stagnant fluids) will most likely result in over temperature of the wire and failure at that point. With this in mind, anyone applying traditional resistance type, electric heating elements must be very aware of maintaining very intimate contact between the heating element and the item or process being heated.
Whenever applying electric heating elements, the consultation of an applications expert is always recommended. They will be able to consider many other operational factors such as wire watt density, conduction properties, control scheme and overall thermal system dynamics.
Ceramic Thick-Film Heaters for OEM Analytical and Medical Equipment
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| Ceramic heating element |
Many traditional electrical heating elements are limited in size and efficiency due to the balance required between conductor temperatures and the the heat transfer properties of the dielectric material used in their construction. Sometimes the mass required to insulate electrically is at odds with the ability to drive the heat into the part. Metal sheathed heaters use compacted magnesium oxide, or wafers of mica for dielectric. While these provide good electrical insulation, they also inhibit thermal transfer from resistance element to the external part. Flexible heating elements use a variety of rubbers or fluoropolymer elastomers that sandwich the resistance element. While these designs are dielectrically strong, and allow for excellent heat transfer, they are limited by the maximum operating temperatures and watt densities of the elastomer.
A newer, alternative technology is “thick-film” ceramic heaters, a process of depositing a resistor “trace” of tungsten paste on top of a ceramic part in a process very similar to screen printing. The deposition process allows for close control of thickness and width of the resistor, thus accurately controlling the conductor resistance, wattage, watt density, and uniformity of the heated part.
The use of ceramics as the heater body (referred to as a heated part), has many advantages. Ceramics are chemical inert, offer excellent thermal conductivity, impervious to moisture, and are very durable. The downside to using ceramics as heaters, however, is the difficulty in machining to very tight tolerances. In recent years though, many of the ceramic machining hurdles have been overcome through advanced ceramic machining processes.
In the early years of development thick-film ceramic heaters had a few major challenges. Dealing with mis-matched expansion coefficients between the ceramic substrate and the conductor trace was considerable. Years of research now have yielded excellent data on compatible materials making this problem much less significant. Another challenge is controlling the tolerance and repeatability of the heater resistance from part-to-part. Improvements and advancement in this area are made possible with laser etching, tighter screening procedures, and advanced machining.
The use of ceramics provided many interesting possibilities in heater design, and many materials were tested and researched. The most common ceramics used for thick-film heaters today are alumina (Al2O3), silicon nitride (Si3N4), beryllium oxide (BeO), and aluminum nitride (AlN). Each material has its own unique chemical and physical properties, but all exhibit good thermal conductivity and good dielectric properties.
The combination of excellent thermal conductivity, high dielectric, high watt densities, precise thermal profiling, and custom shapes and sizes that make thick-film ceramic heaters so attractive to equipment manufacturers. Providing more heat in smaller areas is easier than with traditional heaters. Additionally, some of the ceramics used are non-contaminating and moisture-proof, making them excellent candidates for clean and ultra-clean applications.
Ceramic thick-film heaters have many advantages over metal or elastomer sheathed heaters beyond just providing a more compact component. They are very fast acting, durable, moisture proof, and contamination proof. They can be designed and machined to virtually any size or shape, watt density, voltage, and distributed wattage profile. While the initial design and prototyping requires investment in time and money, the resulting product can be mass produced economically and with repeatable accuracy and quality.
For more information, contact:
BCE
(510) 274-1990
Suggested Watt Densities for Electric Heating Elements
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| Always consider proper watt density for your electric heater application. |
The rates below are recommended watt densities for use with various materials. Safe values vary with operating temperature, flow velocity, and heat transfer rates. In general, the higher the material temperature, the lower the watt density should be, especially those materials which coke or carbonize, such as oils. Watt densities should be low if a material is being heated to a temperature near where the change of state to a vapor occurs (water to steam @ 212°F) since the vapor state has much poorer heat transfer capabilities.
| Material being heated | Maximum Operating Temp.°F | Maximum Watts Per Sq. In.* |
| Acid Solutions: Acetic Chromic (5%) Citric Ferric Chloride (40%) Hydrochloric Nitric (50%) Sulphuric |
212 Boiling Boiling Boiling 150 Boiling Boiling |
40 40 40 40 30 40 30 |
| Alkali & selected oakite cleaning solution | 212 | 40 |
| Asphalt binder, tar, other viscous compounds | 200 300 400 500 |
8 7 6 5 |
| Caustic Soda 2% 10% 75% |
210 210 180 |
45 25 25 |
| Coffee (Direct Immersion) | Boiling | 90 |
| Dowtherm A® flowing at 1 ft/sec or more Non-flowing |
750 750 |
22 10 |
| Ethylene glycol | 300 | 30 |
| ±Fuel Oils Grades 1 & 2 (Distillate) Grades 4 & 5 (Residual) Grade 6 & Bunker C (Residual) |
200 200 160 |
22 13 8 |
| Gasoline, kerosene | 300 | 20 |
| Glue (heating indirectly using water bath Lead-Stereotype pot) | 600 | 35 on casting |
| Liquid ammonia plating baths | 50 | 25 |
| ** Lubrication Oils SAE 10, @ 130°F SAE 20, @ 130°F SAE 30, @ 130°F SAE 40, @ 210°F SAE 50, @ 210°F |
250 250 250 250 250 |
22 22 22 13 13 |
* * Some oils contain additives that will boil or carbonize at low watt densities. Where oils of this type are encountered, a watt density test should be made to determine a satisfactory watt density.
| Material being heated | Maximum Operating Temp.°F | Maximum Watts Per Sq. In.* |
| Metal melting pot | 500 to 900 | 20-27 |
| Mineral oil | 200 400 |
20 16 |
| Molasses | 100 | 2-3 |
| Molten salt bath | 800-950 | 40 |
| Molten tin | 600 | 20 |
| Oil draw bath | 600 400 |
20 24 |
| Paraffin or wax | 150 | 16 |
| Photographic solutions | 150 | 70 |
| Plating solutions: Cadmium plating Chrome plating Copper plating Nickel plating Tin plating Zinc plating |
40 40 40 40 40 40 |
|
| Salt Bath | 900 | 30 |
| Sea Water | Boiling | 90 |
| Sodium cyanide | 140 | 40 |
| Steel tubing cast into aluminum | 500 to 750 | 50 |
| Steel tubing cast into iron | 750 to 1000 | 55 |
| Heat transfer oils flowing at 1 ft/sec or more |
500 600 650 750 |
22 22 22 15 |
| Trichloretylene | 150 | 20 |
| Vapor degreasing solutions | 275 | 20 |
| Vegetable oil (fry kettle) | 400 | 30 |
| Water (process) | 212 | 60 |
| Water (washroom) | 140 | 80-90 |
* Maximum watt densities are based on heated length, and may vary depending upon concentration of some solutions. Watt density should be kept as low as possible in corrosive applications since higher watt densities accelerate corrosive attack on element sheaths. Consult BCE for limitations.
Important: The above values are estimates. It is strongly suggested that you discuss your requirement with an application expert before you apply any electric heating element in to a process where the proper watt density is unknown.
NEW BCE Clean Flow Electric Mini-Heater with Probe Assembly
Baking, Drying, Laminating, Metal Working, Packaging, Plastic Welding, Preheating, Sealing, Soldering, Shrink Fitting, Synthetic Fabric Sewing.
- Designed for heating of clean gas.
- Gas flow passes over an enclosed heated body;
- not exposed to resistive elements (ni-chrome).
- All parts exposed to gas flow are constructed of
- 304 stainless (other material available).
- High temperatures and ranges are available ask a
- BCE engineer.
Ceramic Thick Film Electric Heating Elements
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| Ceramic thick film heaters. |
Ceramic thick film heaters are easily customized into a variety of shapes and sizes, and provide excellent heat transfer. Long life is assured by precise thermal matching between ceramics and resistor traces.
The heater ceramic substrates provide excellent hardness, wear resistance, and compression strength. The physical properties of the ceramic also provide optimal thermal conductivity and excellent uniformity. Thick film ceramic heaters are perfect for application in analytical equipment, life science equipment, mass spectroscopy, medical devices, semiconductor processing, packaging machines, and in applications ultra pure and chemically aggressive media.
Flexibility in Design:
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| Custom shapes and designs. |
- Virtually unlimited in shape or size.
- Single or double sides, one or two layers per side.
- High purity applications no problem.
- Precise control and uniformity via custom watt densities and patterns.
- Distributed wattage for ideal application of heat to part with minimal losses.
- Multiple heating zone capabilities for more precise control.
- Available in virtually any voltage, AC or DC.
- Integrated sensors including thermistors, thermostats, thermal fuses, and printed RTD's.
- Wide variety of lead configurations conforming to shock and vibration, vacuum and purity standards.
21060 Corsair Blvd
Hayward, CA 94545
Phone: (510) 274-1990
Fax: (510) 274-1999
www.belilove.com
E-mail: sales@belilove.com
Custom Heating Elements and Controls
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| Custom heating element. |
Electric Heating Element Technical Reference Guide
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| Carnot engine diagram (courtesy of Wikipedia) |
The heater application guide provides all the important technical look-up tables required to properly apply electric heaters, such as wattage calculation formulas and examples, properties of metals properties of non-metallic solids, properties of liquids and gases, suggested watt densities, estimates of wattage required, guide for heat losses, suggested sheath materials, installation, Ohms Law, and typical wiring diagrams. The reference document is also very helpful when designing custom electric heating elements and designing a thermal system.





















