brine quantity check

Discussion in 'Water Softener Forum, problems, installation and r' started by lifespeed, May 14, 2012.

  1. lifespeed

    lifespeed Member

    Messages:
    321
    Location:
    California
    How accurate is the brine quantity generated by the timed flow from a fixed restrictor at the end of a regen cycle? In my case I'm using a Fleck 7000SXT with 0.25 GPM restrictor. I wanted to confirm the correct quantity of brine in the tank, so I measured the brine level and calculated the volume. Then I realized I was measuring the solid salt displacing the brine as well. That won't work . . .

    I guess I am wondering how a measured brine quantity that sits in the tank for three weeks measures out after evaporation. Yes, three weeks is along time between regens. I guess we're a low-flow household.

    Is this an issue that warrants concern? Should I put an extra 0.25 gallons in the tank to account for evaporation? Also, where do I find the restrictor to confirm the correct size? Is it behind the clip that holds the brine line into the valve?
  2. F6Hawk

    F6Hawk New Member

    Messages:
    166
    Location:
    Alaska
    Item #9 on page 24/25 is the BLFC... http://www.pentairwatertreatment.co...ment/Manuals/7000SXT Service Manual 42775.pdf

    I'd say to know for sure, you'd have to capture all the water sent to the brine tank during a regen (force the 7000 thru all cycles except the brine fill, let that one run while you capture all the water). But I suspect the amount of water is pretty darn close to what the engineers design it for. And if you have the lid on the tank, unless it is very warm in the brine room, probably not much evaporates out. If you wanted to be sure, test your water just prior to a regen, and see if there is any hardness "leakage" because you are running out of brine in the resin the last day before a regen.
  3. Tom Sawyer

    Tom Sawyer In the Trades

    Messages:
    3,173
    Location:
    Maine
    If the cover is on the brine tank I doubt the evaporation will have much effect.
  4. ditttohead

    ditttohead Water systems designer, R&D

    Messages:
    1,836
    Location:
    Ontario California
    The Fleck BLFC and DLFC buttons are highly accurate, and are designed to work at different pressures. I do have a chart that shows how many inches of water will be in a brine tank with undissolved salt... it has never been a highly accurate chart but for float controlled refill systems instead of time refill, you have to use something. See below, and for the field service guys, this chart should be put in your folder for future reference. Use the chart then x.5 to determine the gallons per inch. Add 3" to accomodate the air check, and dont forget to calculate in the brine grid if one is used. I do not miss the days of float refill. :) salt.jpg
    Last edited: May 15, 2012
  5. lifespeed

    lifespeed Member

    Messages:
    321
    Location:
    California
    I calculated 1.16 gallon per inch based on a 18.5" brine tank, so we're in agreement. But that is pure brine, not salt crystals displacing some volume. So you think the 0.5 correction factor is pretty close?

    I've got 7.5" of brine in my tank awaiting regeneration in the next few days. If I take off 3" for the air check (are they all the same?), that gives me 4.5 in X 1.16 gal/in X 0.5 = 2.6 gallons. I'll watch the regen and see what the air check leaves at the end of brine draw, assuming it doesn't leak and drain the tank completely dry like it did last time.

    Perhaps I'll add a half gallon just to be safe. Don't want to dump salt down the drain unnecessarily, but I do need the actual capacity and programming to agree.
  6. ditttohead

    ditttohead Water systems designer, R&D

    Messages:
    1,836
    Location:
    Ontario California
    The amount of water displaced by salt varies with the type of salt, the age, etc.... The 3" aitcheck is a high guess, but this is to minimize potential problems in the field and is a generic number we use and is also not accurate. Float refilled systems tend to use more salt than they claim because we have to accomodate for so many unknowns. The old eries, Schurz, starites, bruners, solos, aquamatics piston valves, etc all had float controlled refill and we knew these were never going to be accurate so we would tend to add a few of water inches to accomodate the worst case scenario. Timed refill is a superior design, and fleck, clack, and autotrol all use it and their flow refill regulators are highly accurate even from 30-90 psi.
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