Danfoss AVPB-F (003H6464) — self-acting differential pressure control and flow limiter, PN 25, DN 25, for district heating and cooling systems. The AVPB-F 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 set to a fixed, factory-preset differential pressure (sealed, non-adjustable). Differential-pressure setting fixed 0.5 bar (factory-preset, non-adjustable); flow rate 0.2–4.5 m³/h; Kvs 8 m³/h. Maximum differential-pressure range 20 bar, media temperature 2–150 °C, cavitation factor z ≥ 0.6, seat leakage 0.02 % Kvs (IEC 60534). Valve body Red bronze CuSn5ZnPb (Rg5); valve cone dezincing-free brass CuZn36Pb2As; seat stainless steel 1.4571; control diaphragm and DP sealing EPDM. Connection External thread G 1¼ A (ISO 228/1), via tailpieces. Media: district heating/cooling circulation water. OEM P/N 003H6464. Technical data quoted verbatim from store.danfoss.com (code 003H6464) and the Danfoss AVPB/AVPB-F (PN 16, 25) operating guide. differential-pressure range 20 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.