L&L Special Furnace Co. Inc. built and delivered a high-uniformity electric box furnace to a valve manufacturer located in the southeastern United States. The front-loading, refractory-lined unit has an effective work zone measuring 22 inches wide x 22 inches high x 20 inches deep. There is a horizontal double-pivoted door with a safety power cutoff switch. A ceramic hearth and standoffs are provided as a workspace. The furnace is equipped with solid-state relays for fast cycle times. These are housed in a NEMA 1 control panel with single-point power connection.
The control system is driven by a Honeywell program control with an over-temperature control to prevent the furnace from over-firing. A digital single-input chart recorder keeps accurate recordings of the furnace process temperature. Kanthal iron-aluminum-chrome coiled elements located on the sides, back and door are controlled in two zones for balancing of temperature gradients from top to bottom.