Keen KF-900 Three-Hopper Subarc Flux Storage Oven


Brief Product Description:

Protect subarc welding flux from atmospheric moisture exposure with the Keen KF-900 subarc welding flux oven. Once removed from factory packaging, hygroscopic granulated subarc flux must be stored in a dry, heated environment to prevent defects in the final weld such as porosity and hydrogen embrittlement. Uniquely-designed, versatile and built to last, this rugged subarc flux storage oven features three individually heated hoppers for storing submerged arc welding flux. The hoppers are structurally connected but separate, and each is individually temperature controlled with a digital microprocessor. The Keen KF-900 provides divided storage capability for multiple types of subarc flux and can be placed centrally in a tool room or shop floor. Each hopper stores 300 lbs of flux for a total combined capacity of 900 lbs, and has a temperature range of 150°F-550°F (38°C-288°C). Made in USA.


About the KF-900 Flux Holding Oven – 900 lbs. Capacity

The Keen KF-900 is a floor-positioned, large capacity subarc flux holding oven that features three, separate but structurally-connected hoppers. Each hopper is individually temperature controlled. Subarc flux is top-loaded in each hopper by way of a hinge-supported lid that is easily lifted manually, and discharged through a slide valve located on the bottom of the unit. Handy, fixed steel bars that stretch across the hopper opening allow the easy emptying of new flux from unopened factory packaging. The flux bags can be placed across these bars, cut open and emptied into the oven hopper. When flux needs to be removed, a container is placed by the user beneath the hopper to catch the granulated flux as it is dispensed. The hoppers are securely mounted onto a stationary, heavy-duty stand.

The welding flux temperature inside each hopper is regulated and controlled by three field-adjustable, digital controllers with bright, LED temperature indicating displays (user can switch from Celsius and Fahrenheit). These microprocessors are housed in a control box on the side of the flux oven hopper, along with a separate on/off indicating red light. This light enables users to quickly view from a distance if the oven is receiving power or has been shut off.

Heavy-Duty Construction

The Keen KF-900 subarc flux holding oven is ruggedly designed to withstand years of use in the most demanding industrial environments. Heavy-gauge steel is used throughout the unit and 2 inch thick, semi-rigid, high-density mineral wool in the oven walls and lids keeps the KF-900 flux oven well-insulated and energy efficient. The exterior features a durable powder-coated paint that is highly resistant to industrial environments and will stand up to years of use. The KF-900’s hoppers have welded seams inside and out, and are welded directly to our custom-built stand.

Performance Heating

Thorough, energy-efficient and quick heating of welding flux is the hallmark of all Keen flux ovens. The KF-900 in particular has 36 / 1000W elements evenly dispersed throughout the cavity of each hopper. The elements are arranged inside the oven hoppers from top to bottom with the last 3 elements at the very top of the oven so if a welding inspector opens the lid to test the temperature, he will get an accurate reading. When loaded with flux, no more than 2” of flux is without direct heating.

Our large-capacity flux ovens like the KF-900 are designed to reduce watt density to the heating elements through a unique wiring series, greatly reducing overall power consumption while increasing heat-up times for cold loaded flux. This eliminates the problem of flux fusing to the heating elements which is a common problem seen in competing brands (Fusing of flux often creates a “gumming” effect causing the granulated material surrounding the elements to meld together).

Quality Temperature Control and Electrical Safety

As standard equipment, Keen KF-900 flux ovens features three UL® approved microprocessors with digital up/down temperature control and LED temperature-indicating display. The temperature reading can be displayed in either Fahrenheit or Celsius, and has a ±0.2 degree accuracy. Handy tactile increment/decrement keys on the controller’s water-resistant front panel enable easy temperature set point adjustment. The controller also features an on/off control mode.

Quality Insulation

Efficient heating design must be supported by quality insulation. The Keen KF-900 features a semi-rigid, mineral wool “board” insulation that is bonded together with a high temperature binder. It is highly thermally-efficient and is installed within the walls and lid of the unit.

Optional Accessories

As an optional accessory, Keen offers slag screens that can be installed at the top of the hoppers. Our slag screens are designed to be a sieve for filtering out contaminants in reused flux as it is being poured back into the flux oven hopper. The hole size on our flux oven slag screens is standard, but we can adjust the screen hole size if you have a different requirement. The slag screens are a fixed size according to the flux oven with which they are used.


Keen has the unmatched ability to customize any of our standard ovens, and/or design one-of-a-kind ovens for unique storage requirements. Welding codes are constantly changing, and Keen is ready to meet the demands of today’s welders.

Additional information

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