Danfoss AVD (003H6646) — self-acting pressure reduction controller, PN 25, DN 25, for district heating and cooling systems. The AVD is a self-acting pressure reduction controller for district-heating water. It is normally open and closes on rising downstream pressure, holding the reduced (outlet) pressure constant at the setpoint. It has a control valve, an actuator with one control diaphragm and a spring for the pressure setting. Reduced-pressure setting range 1–5 bar adjustable; 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, mat. 1.4571; control diaphragm EPDM. Connection External thread G 1 1/4 A (ISO 228/1), via tailpieces. Mounting version Flow. Permissible media: District heating/cooling circulation water (Glycolic water up to 30%). OEM P/N 003H6646. Technical data quoted verbatim from store.danfoss.com (code 003H6646) and the Danfoss AVD / AVD-S (PN 25) pressure reduction controller data sheet. 1.4571; control diaphragm EPDM; Pressure rating: PN 25 (max. 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. No.