# HMI (human-machine interface)

An HMI (human-machine interface) on an oxygen plant is the operator's control panel and display; in WHO's technical specifications for oxygen generator plants (December 2024) it is the control panel/user interface, a programmable logic controller (PLC) system with a colour digital display in SI units.

WHO asks for the display in the preferred language of the destination country and/or English, with a touchscreen and remote monitoring as options, any need for integration into a computerized maintenance management system specified, and data export, for example by USB port, SD card or Bluetooth. The panel displays product purity, which should always be explicitly visible, sieve bed and output pressure, standby and maintenance-needed status, and cumulative hours of operation. WHO's interim PSA specifications of 2020, which the 2024 document supersedes, already asked for a control panel/user interface with numerical and graphical values.

Ultra Controlo datasheets use the term for the digital QuVAC control of the ULTRAVAC vacuum plant, which has a human-machine interface and touch-screen panel; the ULTRAOX datasheet lists a digital touch screen and a PLC. For the full display list see what a PSA plant control panel should display, and for languages [what language an oxygen plant HMI and manuals should use](https://library.ultracontrolo.com/answers/what-language-should-an-oxygen-plant-hmi-and-manuals-use/).

## Sources

- [WHO, Technical specifications for health facility based medical oxygen systems (31 December 2024), oxygen generator plant table, lines 20 and 21](https://iris.who.int/server/api/core/bitstreams/ff437601-add3-44c8-8149-b85f0cdb2b52/content)
- [WHO, Technical specifications for PSA oxygen plants, interim guidance (8 June 2020), line 1](https://iris.who.int/server/api/core/bitstreams/d53996d5-380c-44ae-9fe8-9e529d3270cd/content)
- [ULTRAVAC datasheet, p. 3](https://www.ultracontrolo.com/products/ultravac)
- [ULTRAOX datasheet 2022, p. 16](https://www.ultracontrolo.com/ultraox)

Reviewed: 2026-10-23. Ultra Controlo engineering. https://library.ultracontrolo.com/glossary/hmi/