Danfoss AB-PM DN 20 — combined automatic balancing valve and differential-pressure controller (standard version) for hydronic heating and cooling systems. The AB-PM integrates four functions in one threaded body: a differential-pressure controller that holds a constant Δp across the connected terminal or riser, an automatic flow limiter (presetting caps the maximum flow), a modulating control-valve seat driven by a Danfoss actuator on the M30 x 1.5 connection, and a manual shut-off. Because the valve keeps the differential pressure stable, connected control valves retain their full authority and the branch stays balanced across all load conditions without manual re-commissioning. DZR brass CuZn36Pb2AS (CW 602N) body, PN 16, differential-pressure range 18 KPa to 400 KPa, maximum controllable flow 0.60 m³/h at Δp=10 kPa, stroke 2.25 mm, media temperature -10 °C to 120 °C, mounted in the supply pipe. Connection: External thread ISO 228/1G 1A. OEM P/N 003Z1403. Technical data quoted verbatim from store.danfoss.com (code 003Z1403). Used in commercial refrigeration, provision-room cooling and reefer plant rooms across HFC, HFO and CO2 (R744) refrigerants.