Air handlers for chemical fume hoods should be connected to an emergency power system to maintain flow after a power outage. The fans must be configured to auto-restart so that fans will automatically restart upon shifting to emergency power. The overall ventilation system shall provide at least half of the normal airflow during an electrical power failure.
Required by California Building Code for H occupancies.
Prudent Practices in the Laboratory, Section 8.C.4.5
Losses of power shall not change or affect any of the control system’s set points, calibration settings, or emergency status. After power returns, the system shall continue operation, exactly as before, without the need for any manual intervention. Alarms shall require manual reset, should they indicate a potentially hazardous condition.