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Pumping Systems and Hydraulics Flashcards

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  1. When installing a vertical turbine pump in a wet well, the minimum submergence of the intake bell should be maintained primarily to prevent:

    Answer: Air entrainment and vortexing

    Insufficient submergence allows air vortices to form at the intake, causing air entrainment that can lead to cavitation and loss of prime.

  2. A pump's best efficiency point (BEP) is important because operating far from BEP causes:

    Answer: Increased radial thrust, bearing wear, and reduced pump life

    Operating far from BEP increases radial hydraulic forces on the impeller shaft, accelerating bearing and seal wear and shortening pump life.

  3. In a series pump configuration, what happens to the total head and flow compared to a single pump?

    Answer: Head doubles, flow remains approximately the same

    Pumps in series add their heads at the same flow rate, allowing the system to overcome higher total head while flow stays approximately constant.

  4. Which formula correctly expresses hydraulic horsepower (WHP) for a pump?

    Answer: WHP = Flow (gpm) × Head (ft) / 3,960

    Water horsepower is calculated as WHP = (Flow in gpm × Head in feet) / 3,960, derived from unit conversions of flow, pressure, and power.

  5. A pump experiencing excessive vibration and noise is most likely suffering from which problem?

    Answer: Impeller wear ring clearance that is too large, or cavitation

    Worn impeller wear rings or cavitation cause hydraulic imbalance and bubble collapse that produce vibration and noise in centrifugal pumps.

  6. The term 'priming' as applied to centrifugal pumps means:

    Answer: Filling the pump and suction line with liquid to remove air before startup

    Priming removes air from the pump casing and suction piping so the pump can develop suction lift and begin delivering liquid.

  7. Which maintenance practice is most effective for extending mechanical seal life in a centrifugal pump?

    Answer: Maintaining proper flush water flow and ensuring NPSH is adequate

    Adequate flush water cools and lubricates seal faces while proper NPSH prevents cavitation, both of which are critical to extending mechanical seal service life.