(2) Drill a hole in the outer cap of the thermos bottle using an electric drill.
Make sure that the size of the hole is only slightly larger than the thermometer stem.
The purpose of the hole in the cap is to ensure a minimum clearance of one
inch from the bottom or sides of the insulated container.
(3) Fill the container with a 50/50 mixture of ice and water. Screw on the cap.
Allow five minutes for the water and ice mixture to stabilize.
(4) Insert the bimetallic thermometer stem (the sensing device) into the ice
and water mixture to its immersion depth, which is about 2 inches from the tip of the
thermometer. There is a notch on the stem that serves as a reference point to indicate
the immersion depth (see figure 4-1).
(5) Stir the ice and water mixture one or two turns with the thermometer to
dissipate the stem heat.
(6) Keep the bimetallic thermometer in the ice and water mixture for a
minimum of one minute or until the needle is stable for 30 seconds.
(7) Turn the adjustment nut with a wrench or pliers, to read 32F. The
adjustment nut is located on the bottom of the dial face (see figure 4-1). Make the
adjustment while the bimetallic thermometer is still immersed in the ice and water mixture.
Be careful not to touch the stem of the thermometer with your fingers.
a. Fahrenheit to Celsius. If a thermometer is calibrated on a Fahrenheit scale
and a Celsius temperature reading is required for an inspection report, the temperature
reading can be converted.
Example: Temperature reading of 95 Fahrenheit. Subtract 32 from the
temperature reading and then divide by 1.8.
95 F - 32 = 63F; 63/1.8 = 35C