Mobile Automation delivered the safety and control system for a medical device manufacturer's ethylene-oxide (ETO) steriliser, engineered to AS/NZS 4024 — a regulated sterilising process running on a flammable gas.
Every safety function documented, not just wired
Our engineers built a single register of every safety-related control on the system.
- Traced from the functional description, the step details and the equipment list
- Cross-referenced to the PLC program's control modules and the safety I/O
- Described down to the drum-changeover valves and their individual I/O
- Records which functions sit on safety-rated I/O and which are carried on IO-Link, which is not a safety protocol
- Core testing identified two digital input groups labelled in reverse, corrected and re-tested
Valve control proven on the real process
Process valve control was built and tuned against the plant itself, not bench figures.
- Analogue output for a new control valve delivered through an IO-Link converter, proven before commissioning
- Valve control implemented and tag names brought into line with the rest of the system
- PID control written for two valves
- Loops tuned against flow data captured while the chamber was being pulled down
- Tuned loops built into the process sequence, and the sequence re-tested around them
Wired and earthed for a flammable gas
Because ETO is flammable, the installation was engineered around the hazard.
- Intrinsically safe cabling run in steel conduit through the vacuum room
- Nitrogen tank bonded to a copper earth bar on its own earth from the warehouse board
- Three MCCs installed — main, vacuum and ethylene — with VSD programming and extraction control
- Switchboard plinth and gland plates fabricated, painted and fitted by our own workshop
The results
- A safety system whose every function is verifiable rather than assumed
- Clear separation between safety-rated I/O and IO-Link across the plant
- Valve control and PID loops proven against the running process
- Sterilising sequence re-tested with the tuned loops in place
- Hazardous area wiring, earthing and MCCs suited to a flammable-gas process