Keen KF-300 Subarc Flux Holding Oven – Made in USA


Brief Product Description:

Protect submerged arc welding flux from weld-damaging moisture contamination. Keen’s KF-300 flux oven is designed to maintain factory-fresh subarc flux by heating to industry-recommended temperatures. Innovative, top-loaded hopper design features a bottom-dispensing valve for easy release of heated flux into a transport container. The sturdy subarc flux hopper sits atop a well-built, moveable stand with four casters (two are locking), providing mobility when you need it. Keen’s innovative, energy-efficient design provides rapid heating of flux while reducing overall wattage and minimizing amp draw. Loaded with electrical and design safety features. Standard digitally-adjustable, ON/OFF microprocessor-based controller with ±1 degree accuracy, manual reset high-limit fail-safe control. Made in USA.


About the KF-300 Flux Holding Oven – 300 lbs. Capacity

The Keen KF-300 is a floor-positioned, large capacity subarc flux holding oven. Subarc flux is top-loaded 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 hopper unit is securely mounted onto a rolling stand with 4 heavy-duty casters- two that are swivel with brakes and 2 that are rigid. The wheeled mobility of the KF-300 flux oven enables easy transport. As an added mobility feature, the sides and back of the flux hopper have welded-in channels with threaded bolts; users can easily install lifting eyes into the bolts to enable transport by forklift or other method, if desired.

Heavy-Duty Construction

The Keen KF-300 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 lid keeps the KF-300 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-300’s hopper has welded seams inside and out, and is securely mounted to our custom-built stand with heavy-duty screws.

Performance Heating

Thorough, energy-efficient and quick heating of welding flux is the hallmark of all Keen flux ovens. The KF-300 in particular has 12 / 1000W elements evenly dispersed throughout the flux oven hopper cavity. The elements are arranged inside the oven cavity from top to bottom. When fully loaded, no more than 2″ of flux is without direct heating.

Our large-capacity flux ovens are designed to reduce watt density to the heating elements through a unique wiring series, greatly reducing overall power consumption (The KF-300 is only 1332 watts) 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). According to our testing data the KF-300 can heat 300 lbs of cold-loaded subarc flux to 550F in approximately 4.5 hours, very quick compared to many competing models.

Quality Temperature Control and Electrical Safety

As standard equipment, Keen KF-300 flux ovens feature a UL® approved microprocessor 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.

The microprocessor is 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.

Quality Insulation

Efficient heating design must be supported by quality insulation. The Keen KF-300 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 oven chamber. 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.


We have 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. Please visit our website for more information about our products and detailed technical information about welding consumable storage.

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