Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.

If you've found help here, check back in to let us know how everything worked out.
It's a great way to thank those who helped you.
Need to contact us? Visit https://heatinghelp.com/contact-us/.

TDS vs conductivity

ratioratio Posts: 2,015Member
I'm looking at trying to measure TDS on two boilers, one water, one steam. It looks like what's commonly sold as a TDS meter is really just measuring conductivity and calibrating that somehow to show TDS. Would one of those meters give me a reasonable number out of the box, would I need to calibrate the adjustment factor myself, or ???

Any suggestions for a good TDS meter? www.tequipment.net has a selection, starting at about $45. There's a cheap(?) combo unit that measures TDS, salinity, & pH at the same time. Good idea?

Comments

  • Jamie HallJamie Hall Posts: 10,478Member
    TDS is Total Dissolved Solids -- and is a measure of the concentration of ions in the water. The ions are what give the water conductivity. Hence conductivity is a very good measure of the TDS (it's not exact; it depends a little on exactly what ions are present. Since most of the ions -- and most of the conductivity -- are the commonest ones (Sodium, Calcium, Chloride, Carbonate), the difference can be ignored.
    Jamie



    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.



    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • ratioratio Posts: 2,015Member
    Thanks, @Jamie Hall. I was reading a little about TDS, it said the only real method was to boil a sample down and weigh it; that conductivity was only an approximation. I wasn't sure how close it'd get me, or even if it would make a big difference.
  • Jamie HallJamie Hall Posts: 10,478Member
    ratio said:

    Thanks, @Jamie Hall. I was reading a little about TDS, it said the only real method was to boil a sample down and weigh it; that conductivity was only an approximation. I wasn't sure how close it'd get me, or even if it would make a big difference.

    That's correct. The evaporate to dryness approach is exact -- and a colossal bore (and requires special filters, very good temperature control, a lot of patience, and very very accurate balances). Except in rare instances, conductivity is a dandy surrogate.
    Jamie



    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.



    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
Sign In or Register to comment.

Welcome

It looks like you're new here. If you want to get involved, click one of these buttons!