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Electrolysis

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  • Electrolysis

    what are your thoughts on this. i have seen copper pipe and back pipe together that have been that way for a long time and nothing has happend to the pipes. then on a job they did not spec to use dyelectric unions . then after they ok the cost they said we need to use dyelectric unions, this changes the cost. is this something that is needed???
    Last edited by HVAC HAWK; 01-01-2006, 04:46 PM.
    Charlie

    My seek the peek fundraiser page
    http://observatory.mountwashington.o...nal&fr_id=1040


    http://www.mountwashington.org/weather/conditions.php

    new work pictures 12/09
    http://public.fotki.com/hvachawk/

  • #2
    hawk, i assume that this is on a closed loop heating and cooling system.
    since you typically run chemicals in the water and the oxygen is typically depleated, i think that slows down on the electrolisis. also this is black pipe and fittings. therefore the galvanic action is also eliminated.

    don't quote me since this is more of a havc topic.

    rick.
    phoebe it is

    Comment


    • #3
      Just because you using black steel pipe and fittings does not mean you can't have galvanic action with another metal in the system. If the two metals are far enough apart on the 'Galvanic Scale' then galvanic action will occur provided there is a electrolyte (water or other fluid) and contact between the two metals.

      --------------
      PREVENTING ELECTROLYSIS

      Electrolytic Corrosion (Electrolysis) occurs when dissimilar metals are in contact in the presence of an electrolyte, such as water (moisture) containing very small amounts of acid. The dissimilar metals set up a galvanic action that results in the deterioration of one of them. The following is a list of the more common commercial metals, sequenced according to what is known as the "Galvanic Series":
      THE GALVANIC SERIES

      1. Aluminum
      2. Zinc
      3. Steel
      4. Iron
      5. Nickel
      6. Stainless Steel 400 Series
      7. Tin
      8. Lead
      9. Brass
      10. Copper
      11. Bronze
      12. Stainless Steel 300Series

      When any two metals in this list are in contact, with an electrolyte present, the one with the lower number is corroded. The galvanic action increases as the metals are farther apart in the Galvanic Series. It is not always true that there is greater corrosion the further down the scale one goes. In certain cases one metal immediately following another may be very corrosive.One of the most important facts that an architect should know about a metal or an alloy is its reaction with other metals or alloys with which it may be in contact.This data is given in the Galvanic Series. Here the metals are listed in a sequence in which each metal is corroded by all that follow it. In other words, when two different metals are in contact with each other in the presence of moisture, there will be a flow of current from one metal (the "anode") to the other metal (the "cathode"), and one will be eaten away, or disintegrated, while the other (the"cathode") will remain intact.
      -----------------

      Follow this link to read the rest of the article;
      http://www.berridge.com/Preventing%20Electrolysis.pdf.
      Last edited by Bob D.; 10-19-2007, 04:57 PM.
      ---------------
      Light is faster than sound. That's why some people seem really bright until you hear them speak.
      ---------------
      “If I had my life to live over again, I'd be a plumber.” - Albert Einstein
      ---------
      "Its a table saw.... Do you know where your fingers are?"
      ---------
      sigpic http://www.helmetstohardhats.com/

      Comment


      • #4
        bob d. very good. i remember the galvanic table from apprenticeship school many, many years ago, but you knew where to find it. amazed at you ability to research. i knew someone will have the facts.

        rick.
        phoebe it is

        Comment


        • #5
          thanks rick and bob this info will help .
          Charlie

          My seek the peek fundraiser page
          http://observatory.mountwashington.o...nal&fr_id=1040


          http://www.mountwashington.org/weather/conditions.php

          new work pictures 12/09
          http://public.fotki.com/hvachawk/

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