(a) Approval. Equipment that is in use under the Act on the effective date of this section shall be considered conditionally to have been adopted and approved by the Service.

(b) Limitation on approval. This conditional approval shall not bar a later rejection or disapproval of the equipment by the Service upon a determination that the equipment (1) should be rejected for official use, or (2) is not functioning in an approved manner, or (3) is not producing results that are accurate within prescribed tolerances, or (4) is producing results that are otherwise not consistent with the objectives of the Act.