Select suitable valve types for the following applications:
a. Isolating a heat exchanger.
b. Manual control of the water flow into a tank used for making up batches of sodium hydroxide solution.
c. The valves needed to isolate a pump and provide emergency manual control on a bypass loop.
d. Isolation valves in the line from a vacuum column to the steam ejectors producing the vacuum.
e. Valves in a line where cleanliness and hygiene are an essential requirement.
State the criterion used in the selection for each application.