The 6DR5025-.....-.... is a Siemens SIPART PS2 smart electropneumatic positioner — the workhorse for linear and part-turn pneumatic actuators in hazardous areas. It takes a 4-20mA loop signal and drives a double-acting actuator, with the whole assembly housed in an aluminum flameproof (Ex d) enclosure. The non-contacting position sensing (NCS) means no wear on the feedback path, so calibration holds longer between rounds.
What you need to know for sourcing
RoHS compliance is confirmed since 31-12-16, and the REACH candidate list includes lead (CAS 7439-92-1) above the 0.1% threshold. No export control restrictions apply (AL: N / ECCN: N).
Fit and field notes
The Ex d aluminum enclosure is built for Zone 1 / Division 1 gas groups — the flameproof path contains any internal ignition. Double-acting means it applies pressure to both sides of the actuator piston; you need a 4-20mA signal and a clean air supply, no spring-return. The NCS sensor eliminates the mechanical linkage that drifts on conventional positioners, so expect longer intervals between re-zeroing. On a retrofit, verify the actuator stroke length and mounting bracket pattern; the SIPART PS2 family covers most common linear and part-turn interfaces, but the specific kit (yoke, lever, or NAMUR) is ordered separately.