6:43 Once you close the valve at suction pipe, the head of the pump does no remains constant. By closing the valve you are increasing the piping resistance and therefore the behavior expect for the pump is to reduce the flow rate and increase its head. One of the methods to measure NPSH required uses a closed suction tank.
Good explanation, but boiling temperature should be mentioned to complete the picture. We know water boils at 100degC in our kitchens because we are typically at standard sea level atmospheric pressure and saturation temperature.is 100degC. However at pump inlet, we have a vacuum and pressures could be much.lower than the standard sea level atmos pressure and in some regions the absolute pressure is.lower than the vapour pressure threshold, this.means its boiling temperature is near to the room temperature and the water starts boil and then cavotation.process continues.
In the section on measuring NPSHR using a constant flow test (constant Q) you state @4:56 that outlet valve is kept at a "fixed open position" to maintain constant flow. However, if you throttle down the suction valve to increase flow resistance and decrease NPSHR then you have to adjust the outlet valve to maintain constant flow.
From 5:17 there is mistake in the video. You already mentioned that the NPSHA is the absolute pressure above the vapor pressure but in 5:17 your NPSHA becomes below vapor pressure (your reference point is no longer the vapor pressure).
best video. i seen on npsh explanation .
Best Video on NPSH
i am thaking you so much , the first time i understand what the NPSH is !
a very valuable and proffesional explanation ,
Crystal clear concept clarification about NPSH. Excellent👏👏👏 video.
Make video on Capitation
The best explanation..........
Incredible explanation!
Great and precise simplification for newcomers like me
6:43 Once you close the valve at suction pipe, the head of the pump does no remains constant. By closing the valve you are increasing the piping resistance and therefore the behavior expect for the pump is to reduce the flow rate and increase its head. One of the methods to measure NPSH required uses a closed suction tank.
Good explanation, but boiling temperature should be mentioned to complete the picture.
We know water boils at 100degC in our kitchens because we are typically at standard sea level atmospheric pressure and saturation temperature.is 100degC.
However at pump inlet, we have a vacuum and pressures could be much.lower than the standard sea level atmos pressure and in some regions the absolute pressure is.lower than the vapour pressure threshold, this.means its boiling temperature is near to the room temperature and the water starts boil and then cavotation.process continues.
what can I say...complete presentation for beginners
please like this video and share among needful. Also, subscribe this channel for my motivation. thank you guys !!!
Superb explanation 👌
In the section on measuring NPSHR using a constant flow test (constant Q) you state @4:56 that outlet valve is kept at a "fixed open position" to maintain constant flow. However, if you throttle down the suction valve to increase flow resistance and decrease NPSHR then you have to adjust the outlet valve to maintain constant flow.
Best explanation. Thanks
Very creative ..thanks a lot
Excellent, nailed it!
hi, why frictional loses increase when we throttle? great vid by the way thx.
Grt explanation
what happen if the NPSHa is 3,6 bar but NPSHr 4,6 bar?
known vapor pressure 3,1 bar
From 5:17 there is mistake in the video. You already mentioned that the NPSHA is the absolute pressure above the vapor pressure but in 5:17 your NPSHA becomes below vapor pressure (your reference point is no longer the vapor pressure).
Thank you sir
thanks
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You’re welcome 😊
The velocity is a decrease in pressure
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Great presentation, horrible ai voice.
Sounds like something for Alterra employees.
The voice sounds uncanny form the PDA voice in Subnautica
thanks