Section 8. The commissioner shall appoint and may remove a deputy commissioner. The position of deputy commissioner shall be classified under section 45 of chapter 30 and the salary shall be determined under section 46C of said chapter 30. The deputy commissioner shall have the same qualifications in training and experience as required by the commissioner. The deputy commissioner shall perform such duties as the commissioner may determine and shall, in the case of a vacancy in the office of the commissioner, or during the commissioner's absence or disability, exercise the powers and perform the duties of the office of commissioner. Said deputy commissioner shall devote full time to the duties of the office.