Update the tank External Flow state

This process depends on the state of the devices configured to indicate flow into or out of the tank. The possible states are the following:

• Receiving. The flow is going into the tank but not out.

• Delivering. The flow is leaving the tank but does not return.

• Floating. The flow is both into and out of the tank.

• Inactive. No flow is into or out of the tank.

• Unknown. There is no information on the flow direction.