1. Getting Moisture into the SIMS - Avoid, Avoid, Avoid!
When performing validation studies on a pressurized steam sterilizer, with an AVS or Validator 2000, there are extra precautions which need to be taken to avoid moisture wicking up the thermocouple wires into the SIM.
Kaye thermocouple wires are constructed with an inner Teflon sleeve covering each wire (red & blue) as well as an outer clear Teflon coating covering both wires. When ordered as a probe, the Kaye thermocouples also include a welded tip which is covered with a Teflon heat shrink tubing to protect the tip and to prevent moisture from wicking up the wire from the inner and outer sleeving. If you purchase spools of wire and make your own tips you should always order the thermocouple tip kit which include the Teflon shrink tubing to make your own tips. Using bare tip wires without the tip is the cause of 90% of the water which can wick up to the SIM. Water in the SIM can affect the cold junction readings as well as harm electronics and corrode the terminal strips.
Even with a proper tip, the outer Teflon tip is slightly porous or could be damaged or cut during normal use. In this case many customers utilize what is called a drip cut in the wire to avoid any moisture.
How to add a drip cut: Remove 4 inches(10cm) off the outer insulation from each thermocouple at a point where natural drainage can take place without water reaching the SIM. Also, it is recommended to shave open approximately ¼ inch from each of the inner wire jackets at opposite ends of the outer insulation drip cut. This permit condensation drainage from within the individual wires.
