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A leader in the heat-treating and forging industry was looking for ways to make their process more efficient, cost-effective and accurate. They have over 30 furnaces that Watlow had the opportunity to work on and prove its products are a good fit for the customer.
A large gas fire furnace containing four chambers currently uses the 8AWG Type K in a one-inch Inconel® thermowell one foot into the furnace through the insulated wall. Point-to-point thermocouple wires, heavy gauge, are stuffed down the thermowell and are attached to the furnace. These back to a PLC in a remote control room. There are four control thermocouples on each furnace with only one actually controlling, although any of the four could be utilized. The company would like to modernize their control systems. It is very important to control the temperature of all four sections of the furnace so that it is uniform. A typical furnace run is about 24 hours at 1,200 to 1,800 degrees F.
Watlow wanted to upgrade the controllability of the furnace for performance. Every 30 days the furnace is checked or maintained. The engineers want to minimize this. To best achieve controllability and accuracy, Watlow created a multiple approach. One is to replace the 8AWG and thermowell with 0.375-inch mineral insulated thermocouple for better thermal installation and ease regarding the replacement process. The Type K is also replaced with WATCOUPLE thermocouple for longer life. The SERIES DX temperature transmitters is utilized to bus the four sensors onto a DeviceNet™ line for simpler wiring back to the control room. Adding the SERIES DX means there is only one wire instead of four pairs of wire. It makes it much more flexible and cost-effective. The SERIES DX showed great resilience because it survived extreme hot and cold temperatures.
For more information, contact Watlow Electric Manufacturing Company at 800-4-WATLOW or go to www.watlow.com.