06Decommissioning and storage

Safe shutdown and electrical disconnection#

1. Reduce the current to 0 A and stop electrolysis.
2. Turn off the DC output, then the external disconnect or breaker.
3. Circulate to cool it down, then turn off the pump and temperature control.
4. Do not disconnect the DC cables straight away.
   • Allow time for the charge to dissipate and measure the terminal voltage before disconnecting with tools.

Depressurise the gas paths#

Drain the electrolyte and seal it#

1. Place labelled, alkali-compatible containers under the discharge point.
2. Stop circulation and drain the electrolyte from the lowest point of the loop.
   • With the oxygen and electrolyte outlet at the top open to atmosphere, the electrolyte in the stack runs out through the electrolyte inlet at the bottom.
3. Push the remainder out through the inlet at the bottom with low-pressure nitrogen or dry air fed into the oxygen and electrolyte outlet at the top.
   • Keep it to 0.3 bar or less, within the margin by which the anode side normally runs above the hydrogen side. Use a regulator with a 0–1 bar gauge.
   • Continue until only gas comes out of the inlet.
   • The hydrogen side drains upward, so liquid does not run out of it. Electrolyte does not circulate there and what remains is little more than water that crossed over, so cap it as it is.
   • Do not tilt it by hand to drain it; its weight makes that dangerous.
4. Disconnect and cap.
   • Disconnect the external lines from the electrolyte inlet, the oxygen and electrolyte outlet and the hydrogen outlet, and cap or plug every port.
   • Disconnect the DC cables and protect the terminals from contact and moisture.
5. Confirm every port is securely capped and there is no active leakage.