Running Up the Heat with a New RTD

May 5, 2008
Weed Instrument Model 3312B is the Solution for the Severe Load Probe Application

Autoclaves, sterilizers and freezers—they are the “lions and tigers and bears…oh, my!” of thermocouple applications. They are among the harshest, nastiest environments into which you can put a temperature probe. One of the perennial problems in measuring in these tough environments is moisture ingress that results in low insulation resistance and sensor failure.

Weed purchased and installed a small autoclave to better understand how moisture was getting inside the RTD and lowering insulation resistance. Researchers found that with Teflon- or Silicone-jacketed wire, the two types used almost exclusively in autoclave designs, leakage occurred even when the jacketed material was not abraded. At high pressure and full vacuum, moisture was drawn through the jacketed material and into the bare copper wires leading to the sensor. Therefore, failure was a function of material, not of improper sealing, says Joe Cheatham, Weed vice president.

“The solution for the severe load probe application,” Cheatham continued, “was to go to a unique material impervious to moisture. We chose a proprietary material that not only withstands moisture, but also meets USP Class VI requirements for use in sanitary environments. The result was the new Weed Instrument model 3312B.”

The new material also withstands the typical physical abuse seen in loading and unloading large sterilizers. The material has low memory and, thus, resists kinking.

Model 3312B comes in a variety of both sheath and lead-wire jacket diameters. It is also available in a sharp-pointed version for easy insertion into rubber capped vials, small bottles in tray washers and sterile bags. It does not sacrifice time response, assuring assure quick, accurate temperature measurement without delay or inaccurate readings.

For more information, please contact Joe Cheatham 512-434-2900, x2880, or [email protected].