We received an enquiry from a customer with equipment in a chemical processing plant where the encoder had to be explosion-proof, handle constant chemical exposure, and still give accurate high-resolution position feedback. The Hengstler ACURO AX73 is built for that combination of requirements.
This looks simple, but “corrosion resistant” is a specific spec here, not a general claim – the AX73 is built in high-grade 1.4404/AISI 316L stainless steel, which is the more corrosion-resistant grade used for genuinely harsh chemical or marine environments (a step up from standard 304-grade stainless). It’s ATEX and IECEx certified for gas and dust hazardous areas, and uses a true geared optical multi-turn mechanism (not battery-backed).
In actual application, the AX73 gives up to 22-bit single-turn plus 12-bit multi-turn resolution (depending on interface), runs on SSI, BiSS or Profibus interface, and is rated IP66/67. It’s built to the same ACURO Industry high-precision standard as Hengstler’s non-Ex industrial encoders, so you’re not trading away accuracy for the explosion-proof rating.
From our experience, before we quote this, we would normally check the hazardous area zone/gas group classification required, which interface your controller expects (SSI/BiSS or Profibus), and the specific chemicals or media the housing will be exposed to. Hope this helps.




