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APPLIED T-M PUMPS (different types of pumps (rotary pumps (lobe pump …

- - - - adjustment of flow rates Q and head loss H (PP: chapter - centrifugal pumps)
        
        what is the iso-efficiency curve? :!?:
        
        PURPOSE: Adapt rpm to keep the same flow rate.
- - - - calculation of NPSH
      - NPSHA (A= available)
        
        define as it is available at the location before the pump
        
        NPSHR (related to manufacturer)
        
        is good when not dropped below the P vapor
      - cavitation (some videos) :red_flag:
        
        related with water vapor (not air)
        (EXAM QUESTIONS) :!!:
        
        how to avoid cavitation :question:
        Increase NPSHA
        
        raise tank or level
        
        lower pump
        
        pressurize tank
        
        cool liquid
        
        ?
        
        Decrease NPSHR
        
        large eye area
        
        suction inducer
        
        double suction impeller
        
        larger, slower impeller
        
        parallel pumps
        
        add booster pumps
        
        Other negative effects on NPSH (besides cavitation):
        
        discharge recirculation
        
        suction recirculation
        
        air entrainment
        
        b/c cavitation
        
        damages pumps
        
        influence function of pumps
        
        affect bearings (?)
        
        make noises
        
        graph for the relationship bw NPSHA/R and flow rate :red_flag:
        
        https://www.nuclear-power.net/nuclear-engineering/fluid-dynamics/centrifugal-pumps/net-positive-suction-head/
        
        suction recirculation at the impeller eye
        
        its location is different from the one of discharge circulation :!?:
        
        happening when the pump is used at the un-desired flow rates
        
        EXAMPLE FOR DECREASING FLOW RATE
        
        2 valves before and after the pump and their effects on NPSHA
        
        open the before one: decrease flow rate but increase minor losses = affecting NPSHA (with higher K - minor losses)
        
        better : open the after valve: the minor losses is unchanged = unchanged K (as compared to the first valve closing).
        
        however with low flow rate, if we hear noises then it relates to recirculation (but not cavitation).
        reminder: how to calculate the minor losses?
    - - Remember: measurement of P before and after the pump
        P S: pressure before the pump
        P S > P vapor or P S - P vapor >0
        OR
        P s, stat + P dyn - P vapor > 0