At every point in the smoke chamber the gas temperature at the instant of measurement shall be between 70 şC and a maximum temperature, specified by the opacimeter manufacturer, such that the readings over this temperature range do not vary by more than 0.1 m-1 if the chamber is filled with a gas having an absorption coefficient of 1.7 m-1.
Na vsaki točki v dimni komori mora biti temperatura plina v trenutku merjenja med 70 °C in najvišjo temperaturo, ki jo navaja proizvajalec merilnika motnosti, tako da se odčitki v tem temperaturnem območju ne razlikujejo za več kot 0,1 m-1, če je komora napolnjena s plinom z absorpcijskim koeficientom 1,7 m-1.