4-37. Once the distilling plant is in operation,  which  of  the  following problems  is/are  likely  to  cause priming? 1. A sudden rise of the water level 2. A water level that is too high 3. Both 1 and 2 above 4. A sudden drop in the water level 4-38. The  vacuum  gauge  readings  are nearly  identical  on  the  first-  and second-effect  shells  of  a distilling plant. What is the most likely  cause? 1. Air  leaks  between  the  first  and second  effect 2. Equally  low  water  levels  in both  effects 3. Equally  high  water  levels  in both  effects 4. Obstructions in the flow between  the  first  and  second effects 4-39. Improper  venting  of  evaporator  tube nests can cause which of the following  problems? 1. Condensation  of  steam  in  the vapor  feed  heater 2. Accumulation  of  air  in  the tubes 3. Excessive increase of tube nest steam  to  the  distilling condenser 4. Excessive  increase  of  scale deposits  on  the  evaporator  tube nest 4-40. How  much  scale  preventive  compound is needed for each 4,000 gallons per  day  of  distilling  plant capacity? 1. 1.0   pint 2. 2.0   pints 3. 3.0   pints 4. 1.5   pints 4-41. You have an air leak in the distilling  plant  last-effect  shell and the watch stander has been operating  the  air  ejectors improperly. These  conditions  can produce  which  of  the  following vacuum  readings  in  the  last-effect shell? 1. 34   in.Hg 2. 30   in.Hg 3. 26   in.Hg 4. 10   in.Hg 4-42. When a distilling plant is in operation,  which  of  the  following vacuum tests should you use on joints? 1. Candle  flame 2. Air  pressure 3.  Soapsuds 4. Hydrostatic 4-43. You  must  clean  air  ejector  nozzles with which of the following tools? 1. Special  reamer 2. Rat-tail file 3. Sharp  scraper 4. Metal hole brush 4-44. The  temperature  of  circulating water  has  exceeded  the  allowable 20°F as it passes through the distiller condenser. You know that this situation is not normal. What action should you take first? 1. Clean the air ejectors 2. Inspect  the  condenser circulating  water  systems 3. Check  for  improper  operating procedures 4. Reset the back pressure- regulating  valve 30