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Thread: Having a heck of a time with air leaks

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    stev32k's Avatar
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    Having a heck of a time with air leaks

    Since replacing the 3/8" suction tubing & fittings on the liquidator with 1/2" I've been fighting vacuum leaks for several days. When I can get all the leaks stopped the flow will peg out the rotometer with the valve less than half open. The trouble is I can't keep the system leak free for more than about an hour before another leak develops.

    The Teflon thread tape is just not cutting it. I finally replaced all the teflon tape with Blue Monster thread sealer. I really don't like using the stuff because it is so messy, but it will hold up under a vacuum. When I finished that I thought I had the problem licked until about 3 hours later I checked the system again and there was another leak -ARG . This time it was the $60 needle valve. I tightened up on the packing nut and the leak stopped for about 10 minutes then came back. So I go to Lowes and buy a 1/2" PVC ball valve and new fittings. Thought I would give the teflon tape one more try and sure enough there were no leaks until 15 minutes later. That's where I quit for the day and I'll start back tomorrow.

    With even the smallest of vacuum leaks the flow meter will not go above 4.0 with the valve wide open. When all the leaks are stopped the meter will peg out and the hose will almost collapse when I close back on the flow valve. I'm aiming to maintain 5.5 ppm FC and so far the liquidator has done a good job even with all the leaks. If I can maintain the flow meter at just a little over 4.0 - say 4.25 the FC will stay very close to my target. It seems to stay between 5.0 and 6.0 consistently (at least for the past three days).

    Now I just hope I can get my money back for the needle valve. For all the money I've spent on the liquidator itself, replacing the fittings and tubing, and the valves I could have almost paid for a peristaltic pump - and I wish I had gone that route to begin with.
    20' x 40' IG with vinyl liner volume approx. 35,000 gal.1.5 H.P. main pump, Polaris 280 cleaner W/ 3/4 H.P. booster pump
    Hayward sand filter, 3.14 sq ft, 62 gpm. Stenner 45 MPH10 chlorine feed pump. 1 micron final filter bags (home made and very effective)

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    Re: Having a heck of a time with air leaks

    When you put the tubing into the fittings, use o-ring lube, if you are still using the factory or upgraded fittings.

    I'm wondering how you are getting so much vacuum on the hose. Mine never pulled that hard. I wonder if that's not part of the issue.
    Built in 1957 44,000 gallon in-ground, Wet Edge Primera Stone in Sky Blue, Intelliflo VF Pump, 600 lb. Pentair Triton II TR-100 Sand Filter, CircuPool RG 60 Plus SWG, TF-100 test kit
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    stev32k's Avatar
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    Re: Having a heck of a time with air leaks

    Quote Originally Posted by RobbieH
    When you put the tubing into the fittings, use o-ring lube, if you are still using the factory or upgraded fittings.

    I'm wondering how you are getting so much vacuum on the hose. Mine never pulled that hard. I wonder if that's not part of the issue.
    I use Dow high vacuum silicone lubricant on all the fittings.

    The reason I get so much vacuum is the size of the tube and fittings. Going from 3/8 to 1/2" tube and fittings will reduce friction loss by over 60% for any flow between .2 gpm and 1.0 gpm. As you go above 1.0 gpm the reduction in friction loss gets even greater. Less friction loss means you gain more vacuum throughout the whole system.
    20' x 40' IG with vinyl liner volume approx. 35,000 gal.1.5 H.P. main pump, Polaris 280 cleaner W/ 3/4 H.P. booster pump
    Hayward sand filter, 3.14 sq ft, 62 gpm. Stenner 45 MPH10 chlorine feed pump. 1 micron final filter bags (home made and very effective)

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    stev32k's Avatar
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    Re: Having a heck of a time with air leaks

    I've had to deal with chemical systems for over 40 years and I've never seen one I couldn't make air tight until this one. I've put in feed systems for hypochlorite, chlorine gas, chlorine dioxide, sulfuric acid, sodium hydrosulfide, and ammonia among others. But this one has me beat. I've replaced all the fittings at least twice, I've re-tubed twice, and I still have leaks. They are very small but still leaks.

    If anyone has any suggestions I'd love to hear them.
    20' x 40' IG with vinyl liner volume approx. 35,000 gal.1.5 H.P. main pump, Polaris 280 cleaner W/ 3/4 H.P. booster pump
    Hayward sand filter, 3.14 sq ft, 62 gpm. Stenner 45 MPH10 chlorine feed pump. 1 micron final filter bags (home made and very effective)

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    Re: Having a heck of a time with air leaks

    Do you have a safety vac-alert mine was leaking causing leaks? The air is coming from somewhere turn off one pool valve at a time to see if the bubbles stop. When you shut down the pump does the lid drip a drop, if so you have a leak on the lid? Try bypassing the flow meter and just using the LQ control valve. Spray bubbles around the joints see if they get sucked in.
    21,500 Gallon Vinyl liner pool Eastern Pennsylvania
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    stev32k's Avatar
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    Re: Having a heck of a time with air leaks

    Quote Originally Posted by doublewide6
    Do you have a safety vac-alert mine was leaking causing leaks? The air is coming from somewhere turn off one pool valve at a time to see if the bubbles stop. When you shut down the pump does the lid drip a drop, if so you have a leak on the lid? Try bypassing the flow meter and just using the LQ control valve. Spray bubbles around the joints see if they get sucked in.
    Thanks for the reply. I believe I finally stopped the leaks. Now I'll just keep watching it to see if it stays leak free. I had to replace the flow meter, control valve, and try several different fittings before I finally got them stopped.
    20' x 40' IG with vinyl liner volume approx. 35,000 gal.1.5 H.P. main pump, Polaris 280 cleaner W/ 3/4 H.P. booster pump
    Hayward sand filter, 3.14 sq ft, 62 gpm. Stenner 45 MPH10 chlorine feed pump. 1 micron final filter bags (home made and very effective)

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