Which two blinds are opened first when isolating a tower?

Which two blinds are opened first when isolating a tower?

• A. Outlet and inlet
• B. Inlet and outlet
• C. Top and bottom
• D. Front and back

Answer: (A)

Opening the two ends that connect to the tower—the outlet and the inlet—is done first to relieve any accumulated pressure and purge the lines. By letting the fluid or vapor escape from both sides, you prevent a pressure buildup when you later place the blanking plates to isolate the tower. This initial venting and purge create a safe path for any residual contents, making the subsequent isolation (sealing the ends) much safer and more effective. In short, you want the connected piping to be vented and drained before you lock the vessel off, so there’s no trapped pressure to contend with.

Opening the two ends that connect to the tower—the outlet and the inlet—is done first to relieve any accumulated pressure and purge the lines. By letting the fluid or vapor escape from both sides, you prevent a pressure buildup when you later place the blanking plates to isolate the tower. This initial venting and purge create a safe path for any residual contents, making the subsequent isolation (sealing the ends) much safer and more effective. In short, you want the connected piping to be vented and drained before you lock the vessel off, so there’s no trapped pressure to contend with.