An inspection shall be carried out by an inspector. Any such inspector, upon (a) stating his purpose and (b) presenting to the owner, operator or agent in charge of the premises to be inspected (1) appropriate credentials, and (2) written notice of his inspection authority under § 1316.06 of this chapter, and (c) receiving informed consent under § 1316.08 or through the use of administrative warrant issued under §§ 1316.09-1316.13, shall have the right to enter such premises and conduct inspections at reasonable times and in a reasonable manner.