Net Positive Suction Head Definition, Misconceptions, and Errors

[@AJ-kv4ui]

That background music made me feel I'm watching documentary about WWII :D .Great vid!

[@simpleengineeringsnippets7102]

Thanks! It's the Knight's theme from Monty Python and the Holy Grail. A lot of complaints about the background music....so I stopped using it. Have a great day!

[@greenmountainboy2528]

@@simpleengineeringsnippets7102 can you do a video on how to find the air speed velocity of an unladen swallow?

[@simpleengineeringsnippets7102]

What do you mean....European or African swallow?

[@ChibabaDave]

Ive always thought their theme cuts into a bit that sounds very much like where eagles dare

[@BrianTCarcich]

@@simpleengineeringsnippets7102 I don't know ... AAaaaaahhh!!!!

[@MP-xq2yr]

I liked the video very much but I wish there was no background music. It is very annoying. Sometimes I could not focus on the subject but the voice of the narrator was strong and helpful to back to subject. Thanks

[@simpleengineeringsnippets7102]

I understand

[@flaubenbacher]

Keep up the good work. It's always good to study engineering while listening to Monty Python OST

[@simpleengineeringsnippets7102]

I got so many complaints about the music....sadly I stopped adding it. :(

[@BrianTCarcich]

another +1 for the music ;-) The content is Navier-Stokes for incompressible fluids; nicely done!

[@mikemascaro6792]

I have an irrigation system and this was helpful to understand how to avoid cavitation.

[@simpleengineeringsnippets7102]

Thank you Sir! I'm glad you found it helpful!

[@abdelrahman_alrawi]

Really informative Thank you

[@simpleengineeringsnippets7102]

Thank You as well!

[@danalex2991]

Great explanation Subscribed. I just have a small doubt in the concept of including velocity head in the calculation of NPSHa . If velocity head is included while calculating NPSHa then doesn't it in increase that NPSHa . But somehow it feels counterintuitive to me. I thought cavitation occurs when static pressure head becomes below vapor pressure even though the the fluid may still have velocity. But according to the correct definition like you said , cavitation will not happen even if static pressure head becomes equal to vapor pressure due to the net positive effect of inclusion of the velocity head . Is that correct ? So that means cavitation will start to happen when velocity head also becomes zero ?

[@simpleengineeringsnippets7102]

Hi Dan, You are not alone in your line of thoughts, it is logical. This is why some textbooks and even some handbooks have it incorrect. Including the velocity head with NPSHa is correct. I'll give you another way to think about it. I hope it helps but my experience with many of my students is that including the velocity head in NPSHa remains counterintuitive. The manufacturer is concerned with cavitation INSIDE the pump (internals), where higher velocities are achieved due to the spinning impeller (rpm, impeller diameter, etc.). The peak internal velocity is (somewhat) independent to the velocity head at the pump suction (this is a simplification but if you consider the no slip boundary condition at the tip of the pump impeller it is reasonable). A higher velocity head at the pump suction means less conversion from static pressure head to velocity head in the internals of the pump (to achieve the nearly identical internal liquid velocity). This is why the velocity head is included in the NPSHa calculation. Thanks for your feedback and I hope this comment helps!

[@tompotsy]

Whats with the NFL films music, and rushed explanations?

[@simpleengineeringsnippets7102]

It's Monty Python (Knights Tale from the Holy Grail). Rushed for some...slow for others.

[@dennisbegley9862]

@@simpleengineeringsnippets7102 Music is distracting and takes away from the subject matter

[@AlbyBattyTECHannel]

Thanks for the video! From a colleague (both engineer and youtuber ahah) :D

[@simpleengineeringsnippets7102]

That's awesome!

[@AlbyBattyTECHannel]

@@simpleengineeringsnippets7102 Thanks! :D

[@stephenfulmer1910]

I just want the sound track, forget the NPSH calc

[@ahmedhasabo6647]

Nice thanks lot

[@brianskellenger9344]

Thanks 🙏

[@MohammedBuhindi]

Thanks.

[@WorldEngineersOnline]

Too confusing

[@simpleengineeringsnippets7102]

There is a lot of confusion about NPSH!

[@1amAther]

Is that Shashi Tharoor explaining the topic?

[@simpleengineeringsnippets7102]

No....but keep guessing!