Section 4-203.12 - Temperature Measuring Devices, Ambient Air and Water(A) Ambient air and water TEMPERATURE MEASURING DEVICES that are scaled in Celsius or dually scaled in Celsius and Fahrenheit shall be designed to be easily readable and accurate to ± 1.5°C in the intended range of use. Pf(B) Ambient air and water TEMPERATURE MEASURING DEVICES that are scaled only in Fahrenheit shall be accurate to ± 3°F in the intended range of use. PfWis. Admin. Code Department of Health Services § 4-203.12