单项选择题
A.water seal pipe is plugged B.pump is not primed C.seal ring is improperly located D.impeller is flooded
Which features of a centrifugal pump reduce the need fo...
单项选择题Which features of a centrifugal pump reduce the need for renewing worn impellers and pump casings?（）
A.Close radial clearance between impeller hub and casing B.Low rotational speed of impeller C.Removable end plate D.Replaceable impeller and casing wearing rings
When securing a flash-type evaporator for an extended p...
单项选择题When securing a flash-type evaporator for an extended period of time, you should （）.
A.fill the unit with saltwater B.fill the unit with de-scaling compound C.completely drain the unit D.tightly seal the unit to exclude air
A distinguishing feature of an educator, when compared ...
单项选择题A distinguishing feature of an educator, when compared to other pumps, is the （）.
A.dischargeendbeingsmallerthanthesuctionend B.smallsizeofimpeller C.lackofmovingparts D.easeatwhichthewearingringsmaybechanged
