Danfoss SAVA (003H6689) — self-acting safety pressure relief controller, PN 25, DN 50, for district heating and central heating systems. The SAVA is a safety pressure relief controller that needs no external power or control signal; the setpoint is set on the actuator spring and the reduced/relieved pressure is sensed through an impulse line to the control diaphragm. It is normally open in standby and opens (as a bypass) when the pressure upstream rises above the setpoint, discharging flow to relieve and limit the over-pressure; when the pressure falls back it re-closes. Pressure setting range 1 – 4.5 bar adjustable; Kvs 25 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 EPDM. Flange connection, PN 25 (mating flanges, gaskets and bolts ordered separately). Media: district heating/cooling circulation water (glycolic water up to 30%), pH 7–10. Mounting version Bypass; stem position Normally closed. OEM P/N 003H6689. EAN 5702421542101. Technical data quoted verbatim from store.danfoss.com (code 003H6689).