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  1. SalvationTsai

    Overload problem happened on boiler feed water pump

    To Dear good LittleInch: I am thankful for your continuing hospitable teaching, and I am sorry for my very late reply, was trying to sum up the concepts and the solutions, and also wait for the more detailed pump data from the manufacturer; the manufacturer sent me the data promptly, but the...
  2. SalvationTsai

    Overload problem happened on boiler feed water pump

    To dear good LittleInch: Sorry for my late reply (was trying to organize it more clearly), and many thank you for your every teachings. First I assume I am applying 46Hz (by VFD), and thus I should have a new lowered pump curve. Using the pump affinity law, H is proportional to the square of...
  3. SalvationTsai

    Overload problem happened on boiler feed water pump

    To dear LittleInch and dear ScottyUK: Thank you for your hospital help and generous teaching, It is my fortune to have it. First photo is the pump motor, it was badly worn on the very left part, and I am hoping this could still provide any useful information. Second photo is pump's name...
  4. SalvationTsai

    Overload problem happened on boiler feed water pump

    To dear good LittleInch: Really thank you for your kind reply and good suggestion, I will try my best to obtain the information you mentioned. And thank you for teaching me that the power will increase dramatically higher when past the duty curve (power required climbs faster than the flow rate...
  5. SalvationTsai

    Overload problem happened on boiler feed water pump

    To dear good Artisi: Thank you for your kind suggestion and advice to me, and I am a voluntary helper and student on this case, trying to know more, but indeed I am very poor on the pump studying, but I do try my best to self-study on this domain, and sincerely apologize to you for my novice...
  6. SalvationTsai

    Overload problem happened on boiler feed water pump

    Dear good LittleInch, it is so happy to have your teaching again! And yes this is indeed the continued studying on the boiler feed water pump. The total head 120m is a rated head on the name plate of the feed water pump, and I don’t have the pump curve, because the person who responsible for...
  7. SalvationTsai

    Overload problem happened on boiler feed water pump

    Greetings, and good day to every dear seniors, I found a overload problem occurred on a boiler feed water pump, but I am wondering why it will overload so much, and want to know whether my viewpoints are wrong or right, I will do my best to describe the every factors and situation in this...
  8. SalvationTsai

    Calculate the total head of a boiler feed water pump

    Greetings to all dear good senior engineers: I had calculated the total head of a boiler feed water pump, using the total head calculating equation I found in the book of library. But since it is a actual case in the ship, so there is no answer could verifying my theoretical calculation is...
  9. SalvationTsai

    Theoretical calculation does not match the practical gauge reading on pump suction side

    Dear good LittleInch: Thank you for your clear explanation on the seals of the shaft, I used to assume the seal is on the NRV! I am really happy and glad I could now finally clear on this "idea of a possibility of air leaks into the pump shaft's seal", then in the very end, water in the inlet...
  10. SalvationTsai

    Theoretical calculation does not match the practical gauge reading on pump suction side

    Dear good LittleInch: Thank you for verifying my 2 diagrams, and I had re-drawn the second diagram(with the NRV at discharge side), please kindly see it once more, thank you very much! But I don't quite know where & how the air comes from? I thought the pipe is full of water, or is it leaked...
  11. SalvationTsai

    Theoretical calculation does not match the practical gauge reading on pump suction side

    Dear good LittleInch: It is a big relief to know that my questions makes you smile but not headache. :D And I have draw a concept of your teaching, and still I am wondering my understanding is correct or not understand it properly. Please have a look on it, and still I am very very thank you...
  12. SalvationTsai

    Theoretical calculation does not match the practical gauge reading on pump suction side

    Dear good LittleInch: I am now further understand that the reason why we typically installed the NRV at the pump’s discharge side. It is because that when pump stopped, and my discharged water surface level is higher than the pump centerline for more than 30~40m (as you kindly mentioned...
  13. SalvationTsai

    Theoretical calculation does not match the practical gauge reading on pump suction side

    Dear good 25362: Very thank you for the reference you provided, I will study on it.
  14. SalvationTsai

    Theoretical calculation does not match the practical gauge reading on pump suction side

    Dear good LittleInch: Very thank you for your prompt reply, and thank you for teaching me the relative knowledge of non-return valve, but I am wondering that does a typical non-return valve is usually installed between the pump outlet and discharge valve? And would there be any good or bad...
  15. SalvationTsai

    Theoretical calculation does not match the practical gauge reading on pump suction side

    Dear good BigInch and LittleInch, I am sorry for my late reply, because I am trying to understand to concept which you kindly lectured on me. I had searched the library and internet for theory which could help me clear my confusion, and then I find Bernoulli’s principle is quite fit for my...
  16. SalvationTsai

    Theoretical calculation does not match the practical gauge reading on pump suction side

    Dear good Artisi: Thank you for your kind correcting me that the “suction” is a wrong concept, and using the “inlet” would be a more appropriate word for it, I will keep it in mind, and try to forget the wrong “suck” idea. Dear good LittleInch: Thank you for your verifying my two above...
  17. SalvationTsai

    Theoretical calculation does not match the practical gauge reading on pump suction side

    Dear good DubMac: I really don't know the concept on the "PUMPS DO NOT SUCK", could you please hint me on this? Many of my book I found in the library do describe on the pump, said the pump have suction side and deliver side, please I really wish to figure it out, and son't want to stray on the...
  18. SalvationTsai

    Theoretical calculation does not match the practical gauge reading on pump suction side

    Dear good LittleInch: Your description on “NPSHR must be > NPSHA”, in my humble opinion, isn’t it should be NPSHA > NPSHR in order to avoid the cavitation? And I really thank you for your vivid explanation (cold and hot water in pan) on why the vapor pressure should not be added in when...
  19. SalvationTsai

    Theoretical calculation does not match the practical gauge reading on pump suction side

    Dear good Tenpenny, I am sorry for using wrong way to calculate the pressure of the pump suction side, and could you give me some hint to calculate it correctly? And I am not not understand why NPSHa is a wrong way to calculate it. Thank you for your teaching!
  20. SalvationTsai

    Theoretical calculation does not match the practical gauge reading on pump suction side

    Dear good 1gibson, the elevation of my location is at the sea surface, thank you for your fast reply!

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