Pump cavitation help.
  • ThymThym
    Posts: 108,978

    So like I've been saying, reduce the vacuum and or reduce the temp at the pump. You have a ball valve just after the pump. Turn that nearly off so that only a little trickle gets by. Add a longer hose before the pump, or find some way of cooling it a little (like a bucket of cool water).



    interestingly, with this type of dynamic pump, even shutting the outlet flow off completely wont result in a 0 psi drop. it's still spinning the fluid around really frikin fast and that results in a static pressure difference that will induce flow within the pump head and result in a slight negative pressure at the center-most point of the rotating machinery.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • C_BC_B
    Posts: 80,371
    Lakewood said:

    So like I've been saying, reduce the vacuum and or reduce the temp at the pump. You have a ball valve just after the pump. Turn that nearly off so that only a little trickle gets by. Add a longer hose before the pump, or find some way of cooling it a little (like a bucket of cool water).



    interestingly, with this type of dynamic pump, even shutting the outlet flow off completely wont result in a 0 psi drop. it's still spinning the fluid around really frikin fast and that results in a static pressure difference that will induce flow within the pump head and result in a slight negative pressure at the center-most point of the rotating machinery.

    Thus resulting in the cavitation regardless how far closed the valve is.
    "On it. I hate software." ~Cpt Snarklepants
  • C_BC_B
    Posts: 80,371

    and why are you doing this?


    To clean and sanitize the lines and pump head. That I've already cleaned.
    "On it. I hate software." ~Cpt Snarklepants
  • ThymThym
    Posts: 108,978
    C_B said:

    Lakewood said:

    So like I've been saying, reduce the vacuum and or reduce the temp at the pump. You have a ball valve just after the pump. Turn that nearly off so that only a little trickle gets by. Add a longer hose before the pump, or find some way of cooling it a little (like a bucket of cool water).



    interestingly, with this type of dynamic pump, even shutting the outlet flow off completely wont result in a 0 psi drop. it's still spinning the fluid around really frikin fast and that results in a static pressure difference that will induce flow within the pump head and result in a slight negative pressure at the center-most point of the rotating machinery.

    Thus resulting in the cavitation regardless how far closed the valve is.


    if its really 212 deg F at the pump, yes. but it's unlikey that you will have 0 heat loss, so it's kinda sorta possible to run it slow enough to not cavitate at boiling...
    The only thing between me and a train wreck is blind luck..... - Kenny
  • jeepinjeepinjeepinjeepin
    Posts: 18,078
    In conclusion, either let it come off boil before pumping or run a large copper drain from near the bottom of the kettle straight down to the pump 2' below.
    Sign here______________________________
  • JerryJerry
    Posts: 79,814
    Lakewood said:

    So like I've been saying, reduce the vacuum and or reduce the temp at the pump. You have a ball valve just after the pump. Turn that nearly off so that only a little trickle gets by. Add a longer hose before the pump, or find some way of cooling it a little (like a bucket of cool water).



    interestingly, with this type of dynamic pump, even shutting the outlet flow off completely wont result in a 0 psi drop. it's still spinning the fluid around really frikin fast and that results in a static pressure difference that will induce flow within the pump head and result in a slight negative pressure at the center-most point of the rotating machinery.


    Regardless of pressure drop, a spinning thing will add heat. At my place of work we make one product that uses 25kg of butter, if not heated enough; we soften it by mixing it for a long time in a massive blender. It's a crappy way of heating things if you're trying to heat, but it has an effect that shouldn't be ignored. If just the pressure drop was to blame a closed valve would cause bubbles that quickly condensed.

    And with out movement any where is that 1/6th hp(give or take a lot) going? Really a variable speed thing would be best.


    Yeah like i said a wile back, to sanitize, just let it run into a bucket with out the pump running. To pump it somewhere; let it cool down a little.
    CB's to do list:
    Your mom
  • ceanntceannt
    Posts: 51,204
    This thread reminds me why I like gravity ..... you guys are making my head hurt ....
    Never attribute to malice, that which can adequately be explained by stupidity.
  • ceanntceannt
    Posts: 51,204
    I have ran a lot of calcs for pumps ... but never at boiling .... sanitary force mains rarely get that hot .... unless scoob is involved
    Never attribute to malice, that which can adequately be explained by stupidity.
  • ThymThym
    Posts: 108,978
    ceannt said:

    I have ran a lot of calcs for pumps ... but never at boiling .... sanitary force mains rarely get that hot .... unless scoob is involved


    Ha
    The only thing between me and a train wreck is blind luck..... - Kenny
  • morsmors
    Posts: 231
    I run my march pump at boiling temps all the time. (Not accounting for temp loss in the hose to the pump). Just make sure the out valve is facing straight up (I find even a slight tilt will have a large impact on cavitation). I run wort through my pump and plate chiller for the last 15-20 mins of my boil.
    BJCP A0936 National Beer Judge and Mead Judge
    Cicerone Certified Beer Server
    AHA Member
    CRAFT Homebrew Club
    Sons of Liberty Homebrew Club
    HBT "mors"
  • ThymThym
    Posts: 108,978
    mors said:

    I run my march pump at boiling temps all the time. (Not accounting for temp loss in the hose to the pump). Just make sure the out valve is facing straight up (I find even a slight tilt will have a large impact on cavitation). I run wort through my pump and plate chiller for the last 15-20 mins of my boil.



    Interesting. I suppose having the outlet stright up would help remove the vapor quickly. I might have to try experimenting.
    The only thing between me and a train wreck is blind luck..... - Kenny
  • C_BC_B
    Posts: 80,371
    Outlet straight up.
    IMAG0944.jpg
    2560 x 1440 - 575K
    "On it. I hate software." ~Cpt Snarklepants
  • C_BC_B
    Posts: 80,371
    Mors, what configuration do you have in the kettle? False bottom? Dip tube? Straight inlet? 1/2" ball valve?
    "On it. I hate software." ~Cpt Snarklepants
  • morsmors
    Posts: 231
    It's a 1/2" ball valve with 1/2 silicone tubing. I have a 1/2" coupler on the inside of the kettle but nothing screwed into it so no dip tube atm (I just tilt it when it gets lower).
    BJCP A0936 National Beer Judge and Mead Judge
    Cicerone Certified Beer Server
    AHA Member
    CRAFT Homebrew Club
    Sons of Liberty Homebrew Club
    HBT "mors"
  • morsmors
    Posts: 231
    I should note I do have some restriction due to the shitty QD I use. I have these atm...
    http://morebeer.com/products/kent-male-qd-12-mpt.html

    But if anything they should make it more likely to cavitate...
    BJCP A0936 National Beer Judge and Mead Judge
    Cicerone Certified Beer Server
    AHA Member
    CRAFT Homebrew Club
    Sons of Liberty Homebrew Club
    HBT "mors"
  • C_BC_B
    Posts: 80,371
    mors said:

    I should note I do have some restriction due to the shitty QD I use. I have these atm...
    http://morebeer.com/products/kent-male-qd-12-mpt.html

    But if anything they should make it more likely to cavitate...



    Ha! Those are the cheapos I have to install. I think the problem with mine is the diptube. I think I'll install a couple recirc ports and plan on drawing off the topish and returning at the bottomish.
    "On it. I hate software." ~Cpt Snarklepants
  • C_BC_B
    Posts: 80,371
    Then pulling off the bottom to run to the fermentor.
    "On it. I hate software." ~Cpt Snarklepants
  • morsmors
    Posts: 231
    yeah the Kent disconnects 'work' but they do restrict flow alot... Need to drop a good $200 and get some stainless and end my suffering though.
    BJCP A0936 National Beer Judge and Mead Judge
    Cicerone Certified Beer Server
    AHA Member
    CRAFT Homebrew Club
    Sons of Liberty Homebrew Club
    HBT "mors"
  • C_BC_B
    Posts: 80,371
    mors said:

    yeah the Kent disconnects 'work' but they do restrict flow alot... Need to drop a good $200 and get some stainless and end my suffering though.


    I would like full bore cam locks, but I'm not dropping that kind of cheddar on a hobby.
    "On it. I hate software." ~Cpt Snarklepants
  • morsmors
    Posts: 231
    I'm a gadget whore. What's the point of a hobby if you can't immerse yourself fully in it lol ;-)
    BJCP A0936 National Beer Judge and Mead Judge
    Cicerone Certified Beer Server
    AHA Member
    CRAFT Homebrew Club
    Sons of Liberty Homebrew Club
    HBT "mors"
  • ThymThym
    Posts: 108,978
    mors said:

    I'm a gadget whore. What's the point of a hobby if you can't immerse yourself fully in it lol ;-)



    Yay, toys!
    The only thing between me and a train wreck is blind luck..... - Kenny