Sunrod Split Sheath Miniature Cartridge Heaters

• Small footprint, high heat
• 1/8 inch and 4MM diameters
• 3 - 240 volt operation
• Hundreds of sizes In stock
• Heaters as short as 1/2"

Sunrod split sheath cartridge heaters have a novel, innovative design that removes the failure points of conventional miniature heaters. The design includes a continuous resistor packed in maximum density insulation and welded to the heater connections. Lead wires exit through the insulation with a temperature rating of 500 degrees Fahrenheit. Insulation with a temperature rating of 900 degrees Fahrenheit is also available.

In contrast to typical cartridge heaters, which have cold areas throughout their length and unheated sections at each end, Sunrods generate heat continuously for the whole length of the heater. The even heat dispersion of Sunrod ensures more uniform temperatures for your process. 

Sunrods have a unique hot tip that allows you to reach any part of your operation that requires heat. 

When activated, the split sheath design of SunRod forces its opposing legs to extend into contact with the surrounding bore for optimal heat transfer resulting in reduced operating temperature and an extended operating - by up to five times! 

SunRod elements contract when de-energized, breaking contact with the bore and allowing slide-out removal. SunRods are never going to seize! 

You may now apply heat whenever you want! Drill a small bore to the area that requires heating and insert a hot tip SunRod.

Contact BCE for more information about Sunrod split sheath miniature cartridge heaters. Call 510-274-1990 or visit https://bcemfg.com.

Everything You Wanted to Know About Cartridge Heaters ...

Cartridge Heater (Hotwatt Backer)

Reprinted with permission of Backer Hotwatt

WHAT ARE CARTRIDGE HEATERS?
Cartridge heaters originally consisted of a ceramic-supported heating wire inserted into round metal tube, making them look like cartridges (the likely source of their name). They provide localized heat to restricted working areas requiring close thermal control. Their power density is less than 60 W/in2 and they generate temperatures up to 1,200°F. They range in diameter from 1/8 to 2 in. and vary in length from less than an inch to over four feet. Although they are usually round, they can have square or rectangular cross sections. Standard cartridge heaters account for an estimated 20% of all electric heaters made.

Compacted cartridge heaters were developed about 60 years ago and feature inorganic powder tightly compacted onto the heater wire. This increases their power density to nearly 500 W/in2 and maximum temperatures approach 1,800°F. The need for higher quality tubing and precision-fired crushable ceramics makes compacted heaters cost 1.5 to 3 times the cost of a standard cartridge. They are available in diameters from 1/8 to 1 in. and lengths from 1 inch to over 3 feet.

HOW ARE CARTRIDGE HEATERS MADE?

Cartridge Heater Internal View

For standard cartridge heaters, nickel / chromium heating coils are inserted in a ceramic tube inside a metal housing or sheath. Magnesium oxide filler is then vibrated into the hole to fill any voids. This increases heat transfer to the metal exterior. An end cap is welded on the bottom and insulated leads are installed at the opposite end. For swaged cartridge heaters, the nickel / chromium wire is wound around a ceramic core, placing the wire closer to the metal housing. Magnesium oxide is vibrated in and the heater swaged to a specific diameter. This compresses the MgO so it becomes a better conductor of heat while maintaining its dielectric properties. This improves heat transfer and allows for higher watt densities. Swaging also lets the heaters operate at higher temperatures and better withstand vibrations.

HOW CAN YOU GET THE MOST EFFICIENT HEAT TRANSFER AND LONGEST OPERATIONAL LIFE OUT OF A CARTRIDGE HEATER?
There are several steps users can take. On installation, for example, cartridge heaters should be installed in holes drilled and reamed to no more than 0.002 inches larger than needed. The heaters are routinely sized to never be 0.005 less than the nominal diameter and always at least .001 under the nominal diameter for a slide fit. These close fits ensure rapid heat transfer from the heater to the housing and helps keep the heater as cool as possible, which contributes to a long life. Heaters should not be cycled from low to high temperatures as it shortens their life considerably. Instead, designers should calculate the proper wattage for their applications. The best wattage results in a 50/50 off/on cycle. For temperatures over 750°F, off/on control can be replaced by input voltage regulation through variable transformers or proportioning controllers to minimize temperature fluctuations. If a heater is going to be turned off routinely, the air around it should be kept dry and no impurities (oil, gas,) should be in contact with the heater. That’s because the ceramic material used in cartridge heaters is hygroscopic. Every time power to the heater is switched off, it creates a vacuum inside the cooling housing which draws in air and any nearby impurities from the surrounding area. The moisture or impurities, once inside the housing, can cause a short circuit and result in heater failure.

If a thermostat is used to control the temperature, it should be no more than 0.5-in. from the heater. Mounting it any farther away could let the unit run hot and thereby shorten its life. Another cause of failures is too high a watt density. If the heater was incorrectly specified for an application and provides too much heat, the heater will not be able to dissipate the heat and will fail. Similarly, if the heater is designed for 120 V but is being powered by 240 V, the output wattage will be four times greater than it should be, which can, again, lead to failure.

WHAT OPTIONS ARE AVAILABLE ON CARTRIDGE HEATERS?
There are several options and variations available. Heaters may be three-phase or multiple wattage in a single unit. For instance, an application might need quick heat ups and then a standby circuit to maintain a relatively low temperature using different wattages based on changing thermal loads. Heaters can have wattage outputs that vary over their lengths in order to even out temperatures over a platen or a large surface. Heaters can also have built-in thermocouples, usually at the bottom of the heater and type J or K grounded or ungrounded. If a precision fit is needed, companies can supply centerless ground diameters. They can also supply certain heaters at higher voltages (300 to 600 V).
Heaters used in corrosive environments can be Teflon coated or electro-polished. Heaters that need hermetic sealing or will be used in a vacuum application can be ordered with ceramic-to-metal seals that withstand temperatures to 1,000°F.

CAN CARTRIDGE HEATERS BE USED IN LIQUIDS AS IMMERSION HEATERS?
Yes, when applied with a mount- ing fitting. Not all cartridge heaters made as immersion heaters are completely moisture sealed. The heater and bushing are submersible but the termination end is not necessarily sealed. If an application is in a high humidity area, however, the termination area should be sealed. Seals can be silicone rubber or Teflon which are good to 400°F, or epoxy potting which can handle temperatures to 265°F.

WHAT ARE SOME OF THE TERMINATION OPTIONS OFFERED ON CARTRIDGE HEATERS?
There are multiple options for cartridge heaters, almost too many to list. Standard options start with straight internally connected leads. External connections are optional on larger sizes, recommended when repairable leads are required. There are also post terminals available on cartridges 15⁄16-in. and larger. For applications with limited space, manufacturers can supply right-angle leads.

There are also several options for protecting leads. Fiberglass or silicone rubber sleeving, as well as ceramic bead insulation, protect against temperatures up to 1,000°F. Additional protection can be provided using flexible conduit or stainless steel braid.

Have a requirement for cartridge heaters? Call BCE now at 510-274-1990 or visit https://belilove.com

Electric Heating Element Application and Engineering Reference Guide

Applying and specifying electric heating elements can be complicated. Make the job easier by downloading our handy reference guide (courtesy of Backer Hotwatt). The reference guide includes many of the electrical, mechanical, and physical properties you'll need to know when calculating wattage, evaluating maximum watt densities, and selecting proper heater placement.

CONTENTS

• 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
• GuideforHeatLosses
• Suggested Sheath Materials
• Thermal Systems
• Installation
• Ohms Law
• Wiring Diagrams
• Mathematical Conversions
• Wire, Cable and Current Capacities
• Wire Gage Data
• Pipe Sizes and Threads
• Resistance Wire - Current vs. Temperature

Get your copy of the guide here.

Contact BCE for any electric heating element or thermal system requirement. Visit them at https://www.belilove.com or call (510) 274-1990.

Flanged and Screw Plug Electric Heating Assemblies for Industrial Applications

Flanged Tubular Electric Heater Assembly
Hotwatt

Electric heating, though not the most energy efficient means of delivering heat, provides some distinct advantages as a means of controlling the temperature or thermal component of fluids and solids throughout commercial and industrial settings.

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.

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

Hotwatt Electric Heating Elements

Hotwatt is a leader in manufacturing resistance heating elements. They have an extensive product line that includes cartridge heaters, immersion heaters ideally suited for heating various liquids, air process heaters for providing hot air and gas up to fourteen hundred degrees, stainless steel strip and finned strip heaters in various sizes, self-contained one piece assembly oil in rope heaters; tubular and finned tubular heaters which have been specially built to resist impact, vibration, corrosion, and temperature extremes; extremely versatile band heaters for a multitude of applications; and ceramic and crankcase heaters for custom solutions. Hotwatt's technical information and accessory items ensure that hard what has everything you need for complete thermal system.

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

Internal view of swaged cartridge heater.

Metal-clad electric heating elements share one very common and very important requirement for optimal performance - get the heat away from the resistance wire and into the work as efficiently as possible.

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.

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.

Electric Heating Element Technical Reference Guide

Carnot engine diagram
(courtesy of Wikipedia)

Here’s a very handy reference document (courtesy of Hotwatt) for the application of electric heating elements in industrial and OEM applications such as extruding, vulcanizing, laminating, curing, bonding and thermoforming.

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.

Electric Heating Element Technical Reference Guide from Belilove Company-Engineers

Cartridge Heaters

Styles of Cartridge Heaters

A cartridge heater is a cylindrical electric heating element constructed by tightly winding nichrome wire around a ceramic bobbin, and inserting the wound bobbin into a metallic tube (sheath). The tube is then backfilled with magnesium oxide (MgO) powder to electrically insulate the nichrome wire from the sheath. The heater diameter is then reduced (swaged) to compact the magnesium oxide for better dielectric, while at the same time improving thermal conductivity.

Cartridge heaters come in many diameters and lengths. They vary in voltages, wattages and watt densities. Sheath materials are typically Stainless Steel of Incoloy 800. The electrical leads terminate from one end of the heater and vary in length and insulation material, depending on application and operating temperatures.

Most cartridge heaters are used in some form of die or platen heating. A close tolerance hole is drilled into a metal block, and the proper diameter heater is then inserted in to the hole. It is best to make sure the diameter of the heater is just a few thousands of an inch less than that of the hole, so that maximum surface contact, thus thermal conductivity, can be achieved. A loose fit will cause the internal temperatures of the cartridge heater to climb and the heater will fail prematurely.

Common die heating, or platen heating, applications are:

• Injection mold platen heating
• Heating medical equipment components
• Compressor sump heating
• Bolt heating
• Extruders
• Packaging equipment
• Sealing equipment
• Analytical equipment

Looking for an excellent source for stock cartridge heaters? Check out his link.

Basics of OEM and Industrial Electric Heating Elements - Part 2

This blog entry, reproduced from an electric heating element basics white-paper from Hotwatt, a leading US manufacturer of OEM and industrial heating elements. To download the PDF version, click this link.

Basic Heat Equations

Electric Heating Elements

It would appear at first that calculating all of the heat transfers and losses in a design would be a daunting task. Fortunately a number of equations were developed that help simplify this task. First the equations were divided into three tasks: the wattage needed to heat a material to a specific temperature in a given amount of time; the wattage needed to overcome the losses at operating temperature; and a special calculation needed to reach a melting or vaporizing point.

This equation calculates the amount of wattage (W) needed to raise the temperature of a material a specific amount in °F (ΔF) in a given number of hours (T), you first need to know the mass (m) of the material being heated and its specific heat value (c):

m × c ×ΔF

W=  -------------------

3.412 × T

The mass and specific heat of some materials may be found at www.hotwatt.com/table1.htm for metallic solids, www.hotwatt.com/table2.htm for solids other than metals, and www.hotwatt.com/table3.htm for certain liquids and gases.

Basics of OEM and Industrial Electric Heating Elements - Part 1

This blog entry, reproduced from an electric heating element basics white-paper from Hotwatt, a leading US manufacturer of OEM and industrial heating elements. To download the PDF version, click this link.

Electric heating elements
for OEM and Industry
(courtesy of Hotwatt)

The simplest definition of an electric heater is any device that changes electrical energy into heat energy. But from that simple explanation, electric heaters explode into a myriad of types, sizes, applications, and designs depending upon what’s being heated, the degree of heating needed, and the method by which the heat is applied.

The measure of electrical energy is called the Joule after its discoverer, James Prescott Joule. Through numerous experiments, Joule determined that the quantity

(Q) of heat transferred from electrical energy is proportional to the square of the current (I² ) multiplied by the resistance (R) for the period of time (t) through which it passes:

Q ∝ I² × R × t

However, one seldom sees a reference to Joules used in modern electric circuits. Instead, the controlling factor becomes that of power (P):

P = I² × R

You’ll note the only difference between the formula for determining power and that of determining Joules is the time component. The time factor in heating becomes readily apparent in any device that gets hot when an electric current flows through it: its temperature rises as time passes.