9.2 A process instrumentation diagram for a flash drum is shown in Fig. E9.2. Steam is condensed in a steam coil to vaporize a portion of the liquid feed, and the liquid product is removed by a pump. There are five control valves for the steam flow, vapor product, liquid product, feed flow, and steam chest (which allows the steam chest to be rapidly evacuated in emergency situations). Determine whether the five valves should be air-to-open (AO) or air-to-close (AC) for safe operation, for each of three cases: Figure E9.2 FT Steam FC FT FC T Condensate V ее Vapor PT PC LT LC Liquid a. The safest conditions are achieved by the lowest temperature and pressure in the flash vessel. b. Vapor flow to downstream equipment can cause a hazardous situation. c. Liquid flow to downstream equipment can cause a hazardous situation. Discuss various scenarios of air failure (or power failure).