The Pneumatic Hard Seal Expansion Valve is a specialized automated throttling control valve, integrating pneumatic actuation, hard-seal technology, and expansion throttling functions. Compliant with international standards (ANSI/ASME, ISO, GB), it features a metal-to-metal hard seal structure (valve core & seat), pneumatic actuator, and optional smart positioner—designed to receive 4-20mA/HART control signals for precise regulation of fluid pressure, flow rate, and temperature during expansion. Ideal for high-temperature, high-pressure, abrasive, or corrosive working conditions, it is a core component in refrigeration, HVAC, petrochemical, and industrial process systems requiring reliable throttling and sealing.