Danfoss AVPB (003H6450) — self-acting differential pressure control and flow limiter, PN 25, DN 40, for district heating and cooling systems. The AVPB closes on rising differential pressure or when the set maximum flow is exceeded, holding a stable differential pressure across the controlled circuit so connected control valves keep their authority. It combines a control valve, an adjustable flow restrictor and an actuator with one control diaphragm and handle for differential-pressure setting. Differential-pressure setting 0.2–1 bar adjustable; flow rate 0.8–12 m³/h; Kvs 16 m³/h. Maximum differential-pressure range 16 bar, media temperature 2–150 °C, cavitation factor z ≥ 0.6, seat leakage 0.05 % Kvs (IEC 60534). Valve body Ductile iron EN-GJS-400-18-LT (GGG 40.3); valve cone dezincing-free brass CuZn36Pb2As; seat stainless steel 1.4571; control diaphragm and DP sealing EPDM. Connection External thread G 2 A (ISO 228/1), via tailpieces. Media: district heating/cooling circulation water. OEM P/N 003H6450. Technical data quoted verbatim from store.danfoss.com (code 003H6450) and the Danfoss AVPB/AVPB-F (PN 16, 25) operating guide. differential-pressure range 16 bar); Temperature range: 2 to 150 °C (district heating/cooling water); HS code: 8481.80. Used in commercial refrigeration, provision-room cooling and reefer plant rooms across HFC, HFO and CO2 (R744) refrigerants.