Why Must a Fever Thermometer Be Shaken Each Time It Is Used?
A fever thermometer is a special kind of thermometer. It shows whether or not you have a fever when you are sick. It is made of glass with a thin tube inside. A bulb at one end is filled with mercury.
When your temperature is taken, the warmth of your mouth makes the mercury expand and rise in the hollow tube. There is a pinched-in place in the tube to keep the mercury from shrinking back into the bulb as the temperature is read.
Because the mercury stays up in the tube, it must always be shaken down before the thermometer is used again. Mercury thermometers are not used in modern clinical settings.
Anyways before recording a temperature using a mercury thermometer, the caregiver shakes the mercury down by holding the thermometer firmly at the clear end and flicking it quickly a few times with a downward wrist motion toward the silver end.
The mercury should be shaken down below 96°F (35.5°C) before the patient’s temperature is taken.