In critical installations, two parallel trains can be used, one duty and one standby, to provide redundancy in case of maintenance or failure.
Duty train
It is the train that operates normally and supplies the installation.
Standby train
It remains available and can take over when the main train is taken out of service.
Operational switchover
The transition must be carried out through a controlled process to avoid sudden pressure fluctuations.
Identical settings
The two trains must have documented setpoints and be tested periodically to ensure the standby is truly available when needed.
