(a) Fiberboard IBCs and composite IBCs with fiberboard outer packagings must be conditioned for at least 24 hours in an atmosphere maintained:

(1) At 50 percent ±2 percent relative humidity, and at a temperature of 23° ±2 °C (73 °F ±4 °F); or

(2) At 65 percent ±2 percent relative humidity, and at a temperature of 20° ±2 °C (68 °F ±4 °F), or 27 °C ±2 °C (81 °F ±4 °F).

(b) Average values for temperature and humidity must fall within the limits in paragraph (a) of this section. Short-term fluctuations and measurement limitations may cause individual measurements to vary by up to ±5 percent relative humidity without significant impairment of test reproducibility.

(c) For purposes of periodic design requalification only, fiberboard IBCs or composite IBCs with fiberboard outer packagings may be at ambient conditions.