A centrifugal feed pump must not be operated unless it is fully primed. The pump casing should be fi...
filled before starting, the suction pipe and pipe branch to the discharge stop valve must also be full. If the
water enters the pump suction by gravity, priming is unnecessary and the pump will remain full of water
when shut down. To fill the pump, open the small air-valve on the top of the pump casing until water
commences to flow, then shut the air-valve.
If the pump is operating with a suction lift, it may be primed either from an independent water supply
or from the discharge line, or by means of a vent connection or exhauster which will evacuate the pump and
suction piping of air. a foot valve must, of cause, he fitted in these cases. The discharge valve and air-valves
should be kept closed during the priming of the puny if done by the latter methods.
参考解析:
1. Which of the following should not be done before the centrifugal pump is started?
A. Priming
B. Opening the vent
C. Closing the discharge stop valve
D. Opening the suction stop valve
2. Which of the following statements is not true?
A. If the pump is running with a gravity, priming is important.
B. To fill the pump casing it is necessary to open the air vent.
C. When the water flows from the air vent, it means priming has accomplished.
D. The suction pipe, the pump casing and the pipe to the discharge stop valve must be primed too.
3. According to this passage, we can infer that “A foot valve” is most probably________ .
A. a stop valve
B. a check valve
C. an air valve
D. a suction valve
4. The phrase “the latter methods” in the last sentence means________.
A. an independent water supply system
B. a gravity priming system
C. an exhauster system
D. a discharge line priming system