In any municipality wherein Title 11 (Civil Service) of the Revised Statutes is in operation, whenever a vacancy occurs in the fire department or force by reason of the granting of a leave of absence as provided by law, the appointing authority shall certify to the Civil Service Commission the reason for such vacancy, the name of the person and his office or position.
The appointing authority may fill temporarily such office or position by the appointment of any person who:
Such temporary employment shall terminate upon the date when the appointee's predecessor returns to his duties, or when it is determined that said predecessor will not return, or sooner when deemed advisable by said appointing authority.
N.J.S. § 40A:14-13