Tank air charge and pressure switch questions

Discussion in 'Pumps and Tanks Well Forum & Blog' started by eldyfig, Nov 6, 2008.

  1. eldyfig

    eldyfig New Member

    Messages:
    32
    Location:
    Folkston, GA
    I think I am finally figuring out this well pump system of mine. I have a pump with a squareD 9013FTW2 pressure switch on a ProSource PS19S bladder tank that supplies well water to a large aerator tank. The aerator tank supplies to a pump with a 9013FSG2 pressure switch on another ProSource tank like the first. This pump/tank supplies the house. Wanted to make sure all pressures were correct.

    The house pump/tank is set to 50/30 as seen on already installed gauge. I decided to check the air charge to the the tanks for the first time since it was installed 2 years ago. Found the air charge on the empty house tank was only 12psi. Pulled out the compressor and pumped it up to 28psi. Turned the pump back on and pressured up the system. Came back up to 50. Turned off power and opened a valve. Couldn't tell the exact cut in pressure the contacts closed at because the crappy chinese gauge that somebody put on started sticking. When the house was built and the well system was installed, I found the gauge on the house pump was cracked and not working. I told my construction manger and somebody installed this Made in China gauge. I will replace it tomorrow so I can verify the cut in pressure. Is it correct to assume that the bladder in this tank was being overexerted with an mt tank air charge of 12 and a cut in of 30?

    The well pump/tank that supplies the aerator has a pressure switch that only has a range nut, not a differential nut. Now, all info I have found says the switching point on the rising pressure (cut out) is adjustable, but not the falling pressure (cut in). However, inside the cover of the switch, it says to turn the nut to raise the on pressure. Is this turn-on pressure or pressure while pump is on? Below that it says the on pressure is 30 and the off pressure is not listed. The non adjustable differential of this switch is suppose to be 20. In reality, it isn't 20. I found this pump set to 30/20 (courtesy of a new SS fluid filled gauge). I am wanting to spread the gap, but with the differential being n/a, it has become a little difficult. I have found that as I tighten the range nut, the differential is increasing a little. Currently, I have it at 36/21. The empty tank has an air charge of 18. I am trying to maintain the cut in at 20-21 and raise the cutout. Why the contradiction between the label in the switch cover and documentation from the supplier? Or, does "on pressure" mean the same as "cut out"? And why isn't the n/a differential always 20.

    One other question...my tanks are 19gal capacity and have a draw down of 5.8 (50/30) or 6.9 (40/20). If draw down is how much water comes out before the pump comes on and the air charge on the tank is 2psi lower than the cut in, am I correct to assume that the tank doesn't fill to capacity, but more like a little over the draw down?

    Hope this isn't too much coming from a newbie. I appreciate all the info here and look forward to help understanding this stuff.
  2. leejosepho

    leejosepho DIY scratch-pad engineer

    I might be wrong, but I suspect not. I believe the bladder can survive full compression or expansion.

    Possibly some outdated stickers or literature still in the factory somewhere.

    Yes, and I believe that is its capacity.
  3. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    It's not possible to get an FSG-2 switch down to a 10 lb differential. 17 lbs is about the best I could ever achieve. Your gauge may not be the only thing that is bad. The fitting your screwing it into may be plugged almost shut.

    A prosource (note I did not capitalize the P) would not like too much pressure against a lowered air pressure. There is no dome in the tank to keep the bladder from overextending itself. This is just one more name Pentair has come up with to market their already failing tanks.

    bob...
  4. eldyfig

    eldyfig New Member

    Messages:
    32
    Location:
    Folkston, GA
    The FSG is on the house pump. Differential is ok at 20. The FTW is the one that has the non adjustable differential and it was originally pumping 30/20 on a new gauge.

    Thanks for your replies on this and the other thread. I really appreciate the help.
  5. Gary Slusser

    Gary Slusser That's all folks!

    Yes you can overstretch a 'bladder'.

    I can't understand the order of things and I'm not clear of what you have, pictures would be great but... If this switch is meant to control the air compressor of an air pump system, from my experience with them, you should have left it and possibly the air pressure in the second tank alone. You may not have the 18" of air in the tank during the full range of the system water pressure.

    So why did you get into checking and changing pressures?
  6. eldyfig

    eldyfig New Member

    Messages:
    32
    Location:
    Folkston, GA
    Here is a diagram of the setup.

    well.JPG
  7. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    I'm'm not familiar with an FTW, so I can't comment on it. 20 lb differential would certainly be better on the motor.

    bob...
  8. eldyfig

    eldyfig New Member

    Messages:
    32
    Location:
    Folkston, GA
    The compressor I pulled out was just a portable compressor from the shop. The tanks are bladder tanks. The air pressure at the shrader valve on a tank with all the water drained should be 2psi lower than the cut in pressure, from what it says on the tank.

    I was checking all the pressures because I wanted to make sure all was correct. From what I read here and in the manual for the tanks was it is a good idea to periodically check the tanks air charge. This all started when I got a gauge to put on the pump pulling from the well. It never had one on it, so I never knew the cut in and cut out. When I put the gauge on and found it to be 30/20, I felt this was too narrow a range.



    From the online catalog that I found, the FTW2 is the same as the FTG2, just NEMA Type 3R instead of type 1. It has to be mounted in vertical position to maintain enclosure rating.
    Last edited: Nov 7, 2008
  9. speedbump

    speedbump Previous member

    Messages:
    4,540
    Location:
    Riverview, Fl.
    Maybe they have a different differential than the standard switch. I have never used one. I do know you can buy several different types of pressure switches, but you don't run into them everyday.

    bob...
  10. eldyfig

    eldyfig New Member

    Messages:
    32
    Location:
    Folkston, GA
    If I ever have to replace the FTW switch, I will certainly switch it to a standard 40/20.

    Thank you guys for the the help. As far as my pressures go, I have them all set up correctly now.
  11. eldyfig

    eldyfig New Member

    Messages:
    32
    Location:
    Folkston, GA
    If I ever have to replace the FTW switch, I will certainly switch it to a standard 40/20.

    Thank you guys for the the help. As far as my pressures go, I have them all set up correctly now.
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