45. For the purposes of the performance by an inspector of his functions under the Act or these Regulations relating to inspection, testing, passing as fit for use for trade and stamping of a meter measuring system a person submitting such a system to an inspector or who an inspector has reasonable cause to believe has possession of such a system for use for trade shall, if requested, provide for the inspector's use such liquid fuel as the inspector may reasonably require, and any liquid fuel so provided shall be returned to the person in question.