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  1. #1
    Join Date
    Apr 2019
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    Chiller COOLING TOWER STRAINERS Question

    We have a large cooling tower water Y strainer where I work installed installed after the pump on the condenser water loop for our chiller system. A young engineer there has installed a fine mesh screen around the original strainer to help catch smaller particles. It's causing the Delta T across the strainer to go higher. Was 1 to 2 psi diff now 3 to 4 psi dif and start up. After 24 to 48 hours it's about 10 to 14 psi. It's effecting the discharge pressure and causing the condenser flow control valve to open close to 90 percent. Just wondering if there is a recommendation out there somewhere about how large the filter screen holes should be. Standard strainer was close to 1/8th inch hole and the added screen is 1/32 of an inch. Any suggestions on strainer screen sizes? Thank you!! Chilly.

  2. #2
    Join Date
    Feb 2016
    Location
    Louisburg Kansas
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    If this is a large system you are better off going with a dual basket strainer with the 1/8" holes in the strainer. Either way the 1/32" is too small.
    No man can be both ignorant and free.
    Thomas Jefferson

  3. #3
    Join Date
    Jul 2018
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    Do you mean it is installed before the pump?

    Sent from my SM-G960U using Tapatalk

  4. #4
    Join Date
    Apr 2019
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    Thread Starter
    They're installed on the pump's outlet Spitz. Also thank you Wayne3298 for the advice. I'll mention it at the meeting tomorrow.

  5. #5
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    Apr 2019
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    Thread Starter
    This whole condenser system is a poor design. Cast iron flapper valves for check valves. No seals. Water always falls back to the tank when the system is shut down. Start up, a wall of rushing water slams into the air eliminators. I had to put soft starts on the pumps to slow down the water when starting the system.

  6. #6
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    Jul 2018
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    I would want a low pressure drop strainer before my pump to protect it. There should be a triple duty valve after the pump. If you need a finer mesh filter I would put it on the outlet.

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  8. #7
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    Feb 2016
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    Louisburg Kansas
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    Draining back to a tank is normally done to prevent freezing of the Tower basin and outdoor piping. Those check valves should be changed to non-slam. The 1/32" screens are called start-up strainers and are used temporarily for start-up of new systems. Soft start-up is a good idea even if you didn't have a problem.
    If they insist on having Y-strainers Sarco makes a scrapper strainer manual and motor driven. The motor driven one can be set up to automatically blow down. They now are running the risk of chiller trips due to the lack of condenser water flow.
    No man can be both ignorant and free.
    Thomas Jefferson

  9. #8
    Join Date
    Nov 2011
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    I agree that 1/32 is too small. Have a site that had a basket with that size holes, and we’d get service calls every month or so, and have to clean the baskets. Changed to 1/8” and problems greatly reduced.

    1/32” to 1/8” is almost a 20% increase in free area.

    Anything that makes it through 1/8” is gonna make it through chiller tubes without getting stuck.

  10. #9
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    Apr 2019
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    Thread Starter
    Thanks Guys! Bringing this info to a meeting tomorrow. I will mention all three of you and your comments. Can't tell you where, but this is a system at a launch pad out at the space center in FL. I appreciate the thoughts.

  11. #10
    Join Date
    Feb 2016
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    Louisburg Kansas
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    You are dealing with the operating contractor. My condolences.
    No man can be both ignorant and free.
    Thomas Jefferson

  12. #11
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    Jul 2018
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    Wisconsin
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  13. #12
    Join Date
    Jul 2018
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    Google search

    "bac cooling tower pumping and piping"

    There is a PDF that has really good info for you to read up on.

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  14. #13
    Join Date
    Nov 2011
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    Quote Originally Posted by Spitz View Post


    Sent from my SM-G960U using Tapatalk

    That’s funny, how are you supposed to clean them when they are between the pump discharge and the check valve!? Usually the check valve is the triple duty valve.

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