# PLC (programmable logic controller)

A USAID RISE operating procedure for PSA oxygen plants in Indian hospitals places the PLC (programmable logic controller) in the plant's control panel and asks operators to ensure that all valves operate as per the PLC program.

The Global Fund daily maintenance checklist for PSA plants asks for the oxygen purity (%) to be recorded from the PLC, and USAID RISE treats a faulty PLC reading as something to calibrate as per the manufacturer's recommendation. For the small UPS that Open Critical Care advises for the control circuit and PLC, see [uninterruptible power supply](https://library.ultracontrolo.com/glossary/ups/).

The ULTRAOX datasheet (2022) lists a digital touch screen and Siemens PLC among the plant components. Under that item it lists oxygen purity, oxygen flow in L/min, total oxygen flow in m³, oxygen pressure in bar, a summary of equipment condition, the next maintenance intervention, a record of all contingencies and alarm information.

## Sources

- [USAID RISE, Standard Operating Procedures: PSA Plant Operations and Preventive Maintenance by the Facility Management](https://media.path.org/documents/SOP_on_PSA_Plant_USAID_RISE_04032022_F7fUBr6.pdf)
- [Global Fund / Build Health International, Daily Maintenance Checklist for PSA plants (Project BOXER)](https://resources.theglobalfund.org/media/xbanfgrc/cr_c19rm-psa-plant-daily-maintenance_checklist_en.pdf)
- [Open Critical Care Oxygen FAQ (answer by Assist International): Is it advisable to have UPS as well as generators for a PSA plant?](https://opencriticalcare.org/faq/is-it-advisable-to-have-ups-as-well-as-generators/)
- [ULTRAOX datasheet (2022), p. 16](https://www.ultracontrolo.com/ultraox)

Reviewed: 2026-10-22. Ultra Controlo engineering. https://library.ultracontrolo.com/glossary/plc/