Emerson is a leading manufacturer of valves, controls and system protectors commonly applied in air conditioning and refrigeration systems worldwide. Founded in 1925 as Alco Valve Company, Emerson Climate Technologies Flo......Emerson is a leading manufacturer of valves, controls and system protectors commonly applied in air conditioning and refrigeration systems worldwide. Founded in 1925 as Alco Valve Company, Emerson Climate Technologies Flow Controls continues to pioneer the control of refrigerant flow through innovative, high performance components, such as thermal expansion valves and filter driers. Our Hermetic Moisture Indicator (HMI) is the most sensitive moisture indicator in the HVAC/R industry. Our line of expansion valves have a stainless steel power element that eliminates power failures caused by corrosion. Our solenoid valves have the lowest leakage in the industry. Our filter driers have a combination of filtration and moisture and acid removal that provides the best protection of any filter drier available. Emerson Climate Technologies Flow Controls is headquartered in St. Louis. Emerson Climate Technologies is a business group of Emerson.