KF40 Flanged, 125 Volt, 15A Female-to-Female Socket Vacuum Feedthrough

KF40 Flanged FeedthroughBACKGROUND

A BCE customer needed to replace a bulky power system located within a chamber.  A custom KF40 three-slot single female receptacle feedthrough was the optimal solution to help reduce size and increase efficiency.


The KF40 Socket Feedthrough needed to satisfy the following criteria:
  • 80°C continuous operating temperature 
  • 125V and 15A
  • Female to female connection
  • Vacuum rating: 10-5
KF40 Flanged Feedthrough

BCE designed a simple yet effective unit using a custom elongated KF40 flange with two three-slot single female receptacles. The customer was able to relocate the power system to the outside chamber increasing the available space within the vacuum chamber while maintaining the desired vacuum rating.

BCE’s Epoxy chemical adhesion, the strongest mechanism of any adhesive bond, made the seal possible.  The viscoelastic nature of the epoxy absorbs vibrations and allows for a better performance by reducing fatigue.

Download the BCE Application Note here.

Here's to a Great 2019 from BCE!

Happy Holidays from BCE!

All of us at BCE (Belilove Company-Engineers) wish our customers, partners, vendors and friends a very Happy Holiday Season and a wonderful 2019!

Save Time and Money in the Long Run: Choose a Custom Electric Heater When It Comes to Heating Clean and Ultra-pure Fluids

Custom heater for fluids
Custom heater for clean and ultra-pure fluids (from BCE)
What do the fuel cell, bio-med, laboratory, food, pharmaceutical, medical, semiconductor, and electronics industries all have in common? Applications in their processes requiring a fast responding and accurate high purity fluid heater.

Each of these industries include manufacturing processes that require a small and efficient heating source as a component of their production. These heaters must be ruggedly designed, made from materials immune to process contamination, and be vacuum tight. The heaters will be subject to high temperatures, harsh solvents, and corrosive gases. Many times they must maintain a seal for full vacuum, demonstrate a unique heating profile, and maintain very close control.

Common requirements in these processes:
  • Capable of handling high vacuum.
  • High temperatures.
  • Isolation the process media from heating element.
  • Isolation from other area of contamination.
  • Very accurate control, including internal sensors.
  • Fast heat up and cool down.
Few manufacturers offer electric heaters with all of these features with an off-the-shelf product, so a custom (or semi-custom) heater is required. Heater customization allows for specific application requirement to be addressed. Examples are type of internal sensor (RTD or TC), the use of chemical inert glass liners, a profiled heating pattern, and specific wetted materials.

Using stock screw plug immersion heater for these applications should be avoided. This category of heater will not stand up to the rigors of the application, as they are designed for general industrial service. They are not intended for high purity, will not meet material compatibility requirements, have poor controllability and are bulky in size.

The answer is in a custom high purity fluid heater designed with the specific process in mind.

Benefits of developing a custom fluid heaters are:
  • Available in a variety of voltages.
  • Available in a wide range of watt densities.
  • Temperatures up to 350°C.
  • Effective heated area can be profiled to generate a liner temperature profile.
  • Vacuum compatible up to 1.0 x 10-8  STD. CC/SEC Helium.
  • Can be provided with internal sensors (RTD or thermocouples).
  • Can be glass lined for ultra pure gas application.
Careful review of the application is important and the help of an experienced heater application engineer is required. Choose a vendor with a long, proven track record of success. The outcome of the test, process or product will be infinitely improved.

The Top Four Reasons Why Cartridge Heaters Fail

Cartridge heaters fail because either the heat generated in the internal resistance wire is not efficiently dissipated or moisture (or a foreign substance) seeps inside the protective sheath, creating a short circuit.

Inadequate heat dissipation results in an elevated internal temperature, which can rapidly breakdown the heating element. Inadequate heat dissipation occurs for several reasons: when machined tolerances are outside of an accepted range (improper fit); if the watt density is too high; or when powered by too high a supply voltage.

1) Loose Fit

Loose fit is the most common cause of premature cartridge heater failure. The bore hole within which they are inserted must be held to tight tolerances. High watt density cartridge heaters are even more sensitive as the internal temperature of the heater can rise rapidly and jeopardize the life of the heating element. To ensure adequate thermal dissipation, the recommended hole diameter is no more than 0.002 in. greater than the nominal diameter of the heater.

Typical allowable watt densities for swaged cartridge heaters are based on fit and operating temperature.
Watt density graph
Max. allowable watt density vs. fit. Click image for larger view.
Graph courtesy of Backer Hotwatt.

2) Too High a Watt Density

The watt density of the heater is vital to its performance. This is a measure of thermal power density and the higher the watt density, the greater the needs are for thermal dissipation. High watt densities can lead to premature failure when thermal dissipation needs are not met, as the internal temperature of the heater will exceed the limits of the resistive heating element.

3) Too High a Supply Voltage

In a resistive circuit, since the resistance is fixed, when the voltage is doubled, the current doubles as well as quadrupling the wattage output. Incorrectly specifying the supply voltage can lead to premature heater failure, as voltage has a dramatic effect on the wattage and the amount of heat generated as can be seen in the following formula.
Heater voltage calculation
Voltage calculation. Courtesy of Backer Hotwatt.

4) Moisture or Contaminant Ingress

Even when cartridge heaters feature heliarc-welded end caps, they are prone to failure when the air surrounding the heater contains impurities or has a high moisture content and the heater’s leads are not adequately sealed. This is due to the nature of MgO insulation: it is a highly hydroscopic white powdered mineral, and when the heater undergoes thermal cycling a vacuum is created, drawing in moisture or other contaminants such as oil, which can result in internal shorting.

Watt Density Selection and Thermal Cycling

Suggested watt density is based on several factors including the fluid medium to be heated, the desired operating temperature and process variables such as flow rate. In general, operating temperature is inversely related to the suggested watt density. Additional considerations are taken when heating a fluid to a point near its boiling point, as phase changes drastically reduce its heat transfer capabilities. Highly viscous fluids or fluids that tend to coke or carbonize also require a low watt density. Highly corrosive solutions also need a low watt density, as the increased watt density increases the potential for corrosion, drastically reducing the life of the heater’s sheath.

Selecting an incorrect watt density can have adverse effects to the response of a thermal system, but it is not the only factor to consider. There are four basic elements to any thermal system, including the thermal load, the heat source, the heat transfer device and the temperature controller.

Thermal power delivered by a heating element is a function of wattage, and a correctly sized heating element will provide an ideal thermal response without rapid cycling of the element. The optimal wattage results in a 50/50 off/on cycle, which prevents or minimizes hunting or temperature overshooting. For more precise thermal control, variable voltage devices or solid-state controllers may be used.

For more information on properly applying cartridge heaters, contact BCE by calling 510-274-1990 or by visiting the cartridge heater section of the BCE website.