Thermostats may become inaccurate due to heat, polymer film forming, age, or abuse. Each fryer should be examined regularly to check the accuracy of the thermostat and/or thermometers. You should use a metal dial-type or electronic thermometer, the accuracy of which is verified, on regular basis. Mercury-filled glass thermometers have a high degree of accuracy and reliability, but they should not be used because of risks of breaking.
To determine the mean temperature of the thermostat, follow these four steps: