When sourcing a used glass-lined reactor, you must prioritize the integrity of the glass lining and the pressure vessel ratings. Key specs include the nominal capacity (L or m³), the design pressure for both the vessel and the jacket, and the allowable temperature range. Ensure the glass lining is a high-grade acid/alkali-resistant enamel (such as 9000 series or equivalent). Additionally, verify the agitator type (anchor, paddle, or turbine) and the motor's explosion-proof rating, especially for chemical processing environments.