Fail-Safe is a concept used to specify the position of process instrumentation in the event of power, air pressure or other utility failures. For instance, the valve supplying the cooling water to a chemical reactor would fail in the open position (fail open) in the event of a power failure. This would provide the maximum cooling to the reactor and prevent dangerous high temperatures in the vessel. Specify the proper fail-safe positions for the valves in the following equipment. Specify either fail open or fail close.

A flammable solvent is heated by steam in a heat exchanger. The valve controls the flow of steam to the exchanger. .

A valve controls the flowrate of reactant to a reactor vessel. The reaction is exothermic.

A valve controls the flowrate of reactant to a reactor vessel. The reaction is endothermic.

A valve controls the flow rate of natural gas to a utility furnace in a power station.

A damper controls the flow rate of air to a utility furnace in a power station..