30 CFR § 22.8
Material required for MSHA records.
In order that MSHA may know exactly what it has tested and approved, it keeps
detailed records covering each investigation. These records include drawings
and actual equipment as follows:
(a) Drawings. The original drawings submitted with the application for the
tests and the final drawings which the manufacturer must submit to MSHA
before the approval is granted to show the details of the detector as
approved, are retained. These drawings are used to identify the detector in
the approval and as a means of checking the future commercial product of the
manufacturer.
(b) Actual equipment. If MSHA so desires, parts of the detectors that are
used in the tests will be retained as records of the equipment submitted. If
the detector is approved, MSHA will require the manufacturer to submit one of
his detectors, with the approval plate attached, as a record of his
commercial product.