单项选择题
If you were operating a centrifugal water service pump with worn wearing rings, the （）.
A.pump would be very noisy B.pump would vibrate excessively C.pump would develop insufficient flow D.stuffing box would leak excessively
单项选择题 The packing installed in the pump stuffing box is lubricated by （）.
单项选择题 The steam coils in a high pressure evaporator used for saltwater service should be de-scaled with （）.
单项选择题 Which of the listed chemicals can be routinely used to maintain the hygienic quality of potable water?（）
