Presets
Playback
Cycle settings
The cycle runs by itself and repeats. Time speed is a multiplier on real time because a real cycle takes about an hour. Changing a setting mid-cycle applies to the stages that follow.
Actions and faults
Model checks
The science
What is modelled
The chamber holds air and steam. Vacuum pulses pump the air out, steam is flushed in, then the pressure is held at the saturation pressure of the target temperature. The load heats through a lagged conduction path, and the lethality of the cycle is accumulated as F0, the equivalent minutes at 121.1 C. A state machine moves through the stages and a relief valve and a watchdog guard against faults.
Equations
- Saturation (Antoine):
log10 PmmHg = 8.14019 - 1810.94/(244.485 + T). - Lethality rate:
dF0/dt = 10(Tcore - 121.1)/10(z = 10 K), in minutes per minute. - Load:
dTload/dt = (Tchamber - Tload) k/τ, with τ growing with the load mass and k larger in steam than under vacuum. - Air and steam balance with exponential approach toward set points.
Checks run in the page
- Saturation pressure against tabulated steam values.
- The F0 definition at three temperatures.
- The hold duration of a full cycle.
- Steam pressure against saturation during the hold, and F0 recomputed independently.
Honest simplifications
A reduced-order model with lumped chamber and load temperatures, a single Antoine fit and exponential valve responses. It is not suitable for validating a real cycle, and sterilisation of real loads depends on packaging, air removal and load geometry that are not modelled here.
What to try
- Press No vacuum pulses and watch the air share in the gauge stay high during the heat-up.
- Inject a vacuum pump fault at the start and see the cycle stall, then fail on the watchdog.
- Press Heavy load, short hold and compare the final F0 with the required value.