EDL Thermocouple Calibration Furnace Specifications and Operating Principle

Three zone construction

General Overview

The EDL Calibration Furnace Model # FUR-1200 has been designed for the testing and calibration of both thermocouples and RTD sensors. Standard calibrations may be performed between 300°C and 1205°C. The FUR-1200 is specially designed to perform high accuracy calibration as well as both long term drift tests and temperature cycle tests. Unique design features in the furnace make thermocouple calibrations both more efficient and highly accurate. The internal Inconel equalization block produces a highly stable and uniform temperature field. Real time test data from a recently shipped unit is provided in the attached graphs.

Our furnace uses a high purity ceramic liner that is over .200 thick, this protection tube diffuses the element energy creating a more uniform temperature field. At high temperature, unlike quartz, the ceramic does not allow metallic ions to diffuse through its wall. For some sensors, such as quartz protected reference sensors, this type of metallic contamination at high temperature could lead to calibration shifts. If the sensor under test is to be subsequently used in a clean environment, such as a wafer processing furnace, the contaminated sensor will ultimately contaminate the environment.

To prevent excessive A.C. noise from being transferred to the UUT from the element windings, an Inconel shield, commonly referred to as a cage, has been added to the furnace. This shield or cage reduces the amount of VRMS noise that the measuring instrument will see at the input. Although most instruments are well equipped to handle AC noise, the smaller the value, the smaller the overall uncertainty contribution is from AC noise.

There are two safety mechanisms in this furnace that ensure continuous and safe operation. As with all furnaces great care should be used during operation. The control system utilizes two alarm settings, the first alarm setting is designed to protect the reference sensor and UUT and is usually set slightly above the temperature set point. The second alarm setting is a maximum shutdown point and is factory set to the maximum operating temperature of the furnace. This safety is relay interfaced to the element power and will shutdown all power to the elements.

For thermal cycle and long term drift testing an optional cylinder and UUT test mounting assembly is required. Please see the section on cycle testing for more information regarding these features and options.

Cycle Test Option

Many sensors are not used in a static environment but are subject to extreme temperature shifts during use. Many industrial laboratories have begun assessing the effects of cycling on their temperature sensors. The FUR-1200 is available with a test cycling option that allows the user to cycle their sensors through a temperature, time and dwell cycle. The cycle is accomplished by moving the sensors in and out of the hot zone using a front mounted air cylinder. The process is controlled by an imbedded micro-controller that can be interfaced to the users computer for profile programming. This type of testing allows the user to see initial shifts that may occur due to thermal cycling. Forcing the initial calibration shift prior to installation is beneficial in terms of both economics and safety. The graph below shows a real time cycle graph for a cycle test on a recently shipped unit with the cycle test option.

 

Stability Data

General Specifications

Electrical
Power Requirement . . . . . . . . . . . . . . . . . . . . . . . . 220Vac
Current Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 A
Element Wattage . . . . . . . . . . . . . . . . . . . . . . . . . . .5 000 Watts total
Controller Power . . . . . . . . . . . . . . . . . . . . . . . . . . . 220Vac
Control Thermocouple . . . . . . . . . . . . . . . . . . . . . . Types S
Controller Fuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 A

Physical
Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27"
Width . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18"
Height . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17"
Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250 Pounds
Internal Equalization Block . . . . . . . . . . . . . . . . . . ( High Temperature Nickel Alloy) 8" Long
Temperature Cycle Test Cylinder . . . . . . . . . . . . .Option
Cylinder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21" Long
Cylinder travel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12"

Thermal
Minimum Use Temperature . . . . . . . . . . . . . . . . . 300°C
Maximum Use Temperature . . . . . . . . . . . . . . . . .1200°C
Heat Up Rate Ambient to 300.0°C . . . . . . . . . . . .11.6°C/Min
300°C to 500°C . . . . . . . . . . . . . . . . . . . . . . . . . . . .12.5°C/Min
500°C to 815°C . . . . . . . . . . . . . . . . . . . . . . . . . . . .12.5°C/Min
815°C to 1100°C . . . . . . . . . . . . . . . . . . . . . . . . . . .12.3°C/Min
Stabilization Time . . . . . . . . . . . . . . . . . . . . . . . . . . <4 hours
Stability (K=1) For 20 min period . . . . . . . . . . . . . @ 300°C ±0.065°C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .@ 500°C ±0.065°C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .@1100°C ±0.065°C
Uniformity Full Range in Calibrated Hot Zone . .±0.5°C

Pricing
Fur-1200 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $15 700.00
Thermal Cycle Option . . . . . . . . . . . . . . . . . . . . . . .$2 800.00
Multi-Bore Equalization Block . . . . . . . . . . . . . . . ..$750.00
12 Inch Equalization Block . . . . . . . . . . . . . . . . . . .$750.00
Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .$750.00
Replacement Control Thermocouple Type S . . .$755.00
Replacement Control Thermocouple type K . . . $350.00

 

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