When using weighing scales (battery or AC powered) to measure the content of hydrogen in a system, does the Panel recommend purchasing a Class 1 Division 1 scale? If so, would ventilation be recommended?

It is always recommended that the area in which this work would be done be adequately ventilated and in accordance with the Building Code, NFPA 2 and NFPA 45 if applicable. In the Panel’s opinion, it’s recommended that the weight measuring equipment as you’ve described it  be designed for Class 1, Group B, Division 2. Also consult with the local authority having jurisdiction as to the extent of the area classification.