49 CFR § 172.500 - Applicability of placarding requirements.
(a) Each person who offers for transportation or transports any hazardous material subject to this subchapter shall comply with the applicable placarding requirements of this subpart.
(b) This subpart does not apply to—
(1) Infectious substances;
(2) Hazardous materials authorized by this subchapter to be offered for transportation as a limited quantity when identified as such on a shipping paper in accordance with § 172.203(b) or when marked as such in accordance with § 172.315.
(3) Hazardous materials prepared in accordance with § 173.13 of this subchapter;
(4) Hazardous materials which are packaged as small quantities under the provisions of §§ 173.4, 173.4a, 173.4b of this subchapter; and
(5) Combustible liquids in non-bulk packagings.