(a) Methods. All Class X or Class Y weighing, checkweighing, checkloading, stowage examination, and other weighing services shall be performed by official personnel or approved weighers using approved weighing equipment and according to procedures prescribed in the regulations and the instructions.

(b) Order of service. Weighing services shall be performed, to the extent practicable, in the order in which requests are received. Official personnel must mark or stamp the date received on each written request for service. Precedence will be given to requests for weighing required by sections 5(a)(1) or 5(a)(2) of the Act.