The symbol with the output 'ee' shown in the illustration, is properly called a blocking valve. Which of the following statements describes its function when incorporated into a slow speed diesel engine pneumatic control circuit? Illustration MO-0116

Correct Answer: Option D — The device is used to interrupt the pneumatic signal to port "A" of the distributor shown in illustration MO-0053.

Blocking valves in pneumatic control schemes act as logic elements to interrupt specific pilot control signals, such as cutting the air supply to port 'A' of the air start distributor during interlocking sequences.