How long does the preheating take?

Approximately 20 minutes.
What if the device is stuck on the ignition screen?

Press and hold the power button to force shutdown, then restart the device and reinitiate ignition.
Does the hydrogen generator automatically stop after the metal hydride is fully charged?

The hydrogen generator is equipped with a pressure sensor. When the pressure reaches the maximum level, hydrogen production stops. Once the fully charged metal hydride is removed, the generator will resume hydrogen production.
What is the internal pressure of the metal hydride?

Maximum 0.7 MPa.
Under normal usage, how long can one gas cylinder last?

Approximately 10 hours.
How can the PID reading be reset to zero?

Calibrate using zero air.