Danfoss RLV-S — manual return-side lockshield radiator valve for two-pipe hydronic heating systems, OEM order code 003L0421. The RLV-S is a return-side lockshield (isolating) valve: it lets an individual radiator be shut off for maintenance or removal without draining the rest of the system. Regulation and isolation are set with a 6 mm hex socket in the valve body, normally covered by a screw-on cap. This variant has a O-ring sealed tailpiece nipple. RLV-S DN 10, angle pattern, connection to system G 3/8, connection to radiator R 3/8 (internal thread), Kvs 1.5 m³/h. Body brass, finish Nickel plated. working pressure 10 bar, test pressure 16 bar, flow temperature up to 120 °C. Pair with a Danfoss RA-series thermostatic radiator valve on the flow side. Genuine Danfoss part; technical data quoted verbatim from store.danfoss.com (code 003L0421). OEM P/N 003L0421, EAN 5702425113383. Used in commercial refrigeration, provision-room cooling and reefer plant rooms across HFC, HFO and CO2 (R744) refrigerants.