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 plus or minus one and one half degrees Centigrade (+-1.5 ° C) (thirty-four and seven tenths degrees Fahrenheit (+- 34.7 ° F)) in the intended range of use.
Ambient air and water temperature measuring devices that are scaled only in Fahrenheit shall be accurate to plus or minus three degrees Fahrenheit (+-3 ° F) (plus or minus two degrees Centigrade (+-2 ° C)) in the intended range of use.
D.C. Mun. Regs. tit. 25, r. 25-B1205