What is the safe shutdown sequence for PSA plant maintenance?

The Global Fund standard operating procedure template for oxygen plant operators (9 December 2025, French) notes that most manufacturers give specific instructions that must be strictly followed. Before the shutdown, the template asks the operator to check that an alternative oxygen source is connected and supplying the facility, and to tell clinical and technical staff about the planned shutdown and its duration. Global Fund sustainability guidance (August 2024) asks for a back-up plan so that clinical oxygen needs are met when the plant is shut down for scheduled service.

The USAID shutdown sequence

1. Close the oxygen outlet valve, which sits after the bacteria filter of the oxygen storage tank.
2. Close the air receiver tank's outlet valve and the oxygen receiver tank's inlet valve.
3. Wait 5 to 10 minutes until the gauges on both adsorption towers read zero; the procedure runs the plant for a few cycles until the tower gauges reach zero.
4. Switch off the air compressor.
5. Only for maintenance: drain the pressure in the air receiver and the oxygen receiver through the drain valves at the bottom of the tanks; the oxygen receiver pressure is shown on the operator screen.
6. Switch off the oxygen generator control panel display, then the air dryer.
7. Close the outlet valve of the air compressor.
8. Switch off the generator panel's circuit breaker, the dryer's circuit breaker and the compressor switch at the power panel, then the main electrical power source.

What the Global Fund template adds

• Isolation: close the main product oxygen valve gradually, to isolate the plant from the distribution network or the cylinder filling system.
• Stopping: typically, the central PLC stop button stops all the equipment in sequence; some installations need a manual stop in the order booster compressor, oxygen generator, air compressor, air dryer.
• Not the emergency stop: the template says not to stop the equipment with the emergency stop button, because left in that state it could damage the equipment; the USAID procedure keeps the emergency stop for high-risk conditions.
• Power: if necessary, isolate the electrical supply with the main switch or circuit breaker during maintenance.
• Hot work: grinding, welding, brazing and other hot work only with the plant stopped and after the room has been properly ventilated.

Safety during the work

AIGA 113/20, adopted from EIGA Doc 195, asks for a procedure that defines the checks and actions before shutting down a supply source, and for a manual shutdown procedure, listing actions such as product disposal and equipment venting, where there is no automatic system or it fails. It requires any maintenance to be managed through a permit to work system with a prior risk assessment, and lists, among the generic hazards for maintenance personnel, these precautions:

• Electricity: de-energising, locking out and tagging all equipment before maintenance, which also prevents automatic starting while the equipment is being serviced.
• Pressure: depressurising the system before disconnecting any element under pressure.
• Atmosphere: an individual oxygen detection device for maintenance personnel against oxygen-deficient atmospheres; AIGA also lists oxygen enrichment, which increases the risk of fire.
• Dust: protective equipment when opening the molecular sieve or changing filters on the concentrator.
• Parts: replacement parts to the same specifications as the originals, including material compatibility and cleaning for oxygen service.

WHO's technical specifications for health facility oxygen systems (December 2024) ask for isolation valves after the compressor, before and after the air tank and the product tank, and on the sample line, the product line and any cylinder fill line. The USAID procedure limits preventive maintenance to experienced, properly trained personnel wearing their protective equipment. For hospital pipeline work, see what a medical gas permit to work is.

Emergencies and restart

For an emergency, the Global Fund template is different: evacuate at once if there is immediate danger; if a brief presence in the room is safe, press the emergency stop on the control panel first and, among the other steps, make sure the backup source is supplying the hospital; do not restart until the cause has been fully identified, investigated and resolved. Before any restart, AIGA 113/20 asks for all process parameters, including online analysis, to be verified within limits and, after maintenance, formal confirmation that, among other things, the work has been completed, checked and approved and that all safety permits have been cleared. See how fast a PSA plant reaches purity.