06Decommissioning

Safe shutdown and electrical disconnection

1. Reduce the stack current to 0 A and stop electrolysis.
2. Turn off the DC output, then turn off the external disconnect or breaker.
3. Do not disconnect the DC cables straight away.
   • Stored charge can remain in the DC circuit even at 0 A: the supply, the cables and the stack.
   • Wait until the supply is fully off and enough time has passed for the charge to dissipate, then disconnect the cables with tools.
4. Turn off the circulation pump and any temperature control devices.

Depressurise the gas paths

• Depressurise the connected hydrogen and oxygen discharge paths to ambient, using the normal vent route you used during operation.
• Where there is a pressure indication, confirm there is no residual pressure.

Drain the electrolyte and seal it

1. Prepare for draining.
   • Place a labelled, alkali-compatible container under the discharge point and use secondary containment.
   • Route the wet outlet path safely into the container.
2. Reconfigure the pump so it does not draw from the tank.
   • Disconnect the line between the electrolyte tank and the pump inlet.
   • Leave the pump inlet open to atmosphere so air can enter, which stops it pulling electrolyte back out of the tank.
3. Provide an air break at IN.
   • Disconnect the IN line from any liquid supply and leave it open to atmosphere, so air can enter as liquid leaves through OUT.
4. Pump the electrolyte out of the stack.
   • Turn the pump on and discharge until no more liquid comes out of the stack OUT line.
5. Tilt-drain what remains.
   • Turn the pump off, tilt the stack so the OUT port faces downward, and drain the remainder into the container.
6. Disconnect and cap.
   • Disconnect the OUT line and cap or plug the OUT port. Cap the IN port as well.
   • Disconnect the external tubing from the H2 ports and plug them as required.
   • Disconnect the DC cables from the stack terminals, taking care that a tool does not cause a spark.
   • Protect the terminals from accidental contact and from moisture.
7. Confirm every port is securely capped and there is no active leakage.