Which sequence describes the valve's open and close signals?

• A. Opens at 3533 and closes at 3133.
• B. Opens at 3133 and closes at 3533.
• C. Opens at 3533 and remains open.
• D. Closes at 3533 and remains closed.

Answer: (B)

The timing and order of valve control signals. Signals are issued at specific time codes, with smaller codes occurring earlier. For a valid open-then-close cycle, the valve must receive the open command before the close command, and there should be a later time when it closes.

Opening at 3133 and closing at 3533 fits this: 3133 comes before 3533, so the valve opens first and then closes after some interval. Opening at 3533 and closing at 3133 would reverse the order, implying a close before an open, which isn’t feasible in normal operation. Opening and never closing leaves the valve open indefinitely, while closing and never opening never engages the valve. Therefore, the sequence that opens first and closes later is the correct one.