Announcement

Collapse
No announcement yet.

Help... Descaling Cimbali M27 & need advice

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • #16
    Re: Help... Descaling Cimbali M27 & need advice

    Originally posted by 4548554653161514270 link=1245413520/10#10 date=1245720550
    everything now has a strange pinky / orange residue on it that is almost impossible to scrub off.
    Gday Borat....

    Why the brass components turn Pink is because that is the natural colour of clean (non-oxidised) copper metal. The mild acidity of the Citric Acid bath removes the Zinc from the Copper/Zinc Alloy at an atomic level, which results in an outer layer of pure copper metal maybe only a few atoms in thickness. So long as you thoroughly rinse the acid from the metal after the water-scale has been removed, further reaction should cease.

    Theres no real need to polish the brass parts back to the parent metal unless you dont particularly like the colour of the copper. Over time the copper will oxidise and develop a dark patina anyway. Where you see a pinkish tinge on other metals such as nickel (dont think copper will deposit on chrome), e.g. this is due to electrolytic deposition as a result of dissimilar metals being present in the acidic solution. You should be able to polish this off without too much problem...

    Hope this is helpful...

    Mal.

    Comment


    • #17
      Re: Help... Descaling Cimbali M27 & need advice

      Originally posted by 6E637E6D783D3E3F0C0 link=1245413520/14#14 date=1245749053
      And heres some before & after pics of one the heat exchangers.   The copper area inside that previously had lots of scale, is now a different colour and has a rougher feel to it.

      Do you think they are still ok to use, or does this look like pitting?
      They should be OK Borat but to make sure, you could see if you can borrow a thickness gauge/dial calliper from someone.... Perhaps an auto-mechanic or a machine shop and then measure the thickness of the HX wall in different locations around the HX tubes in order to make a factual decision on their condition.

      I wouldnt have thought that a 30:1 ratio of water:citric acid solution would be that corrosive in a short time. Perhaps the earlier smoothness that you observed was down to the existence of a thin layer of scale?

      Mal.

      Comment


      • #18
        Re: Help... Descaling Cimbali M27 & need advice

        Ok, thanks for the advice. Yes, the copper deposit on the chrome came off pretty easy.

        Ive only got the element now left to descale, and a couple of days wait for some o-rings, then will try and put it all back together.

        Do you think the cast steel external side covers would be cheap to chrome, and would it match the rest of the polished stuff? The sides are painted black at the moment.

        Comment


        • #19
          What is this? - ok to put in acid bath for descaling?

          Can anyone tell me please what this is?  Its out the M27 Start and is one of the first components after the water inlet. Is it ok to put in the acid bath for cleaning?

          Im a bit reluctant to take the top off to have a look inside, as I fear there is a gasket underneath which may be hard to get.  


          Comment


          • #20
            Re: Help... Descaling Cimbali M27 & need advice

            Originally posted by 3D302D3E2B6E6D6C5F0 link=1245413520/17#17 date=1245753371
            Do you think the cast steel external side covers would be cheap to chrome, and would it match the rest of the polished stuff?   The sides are painted black at the moment.
            Imagine they could be chromed without a lot of trouble but have no idea with regard to cost. You might need to canvas "Electro-platers" in your local area and get a couple of quotes. An alternative may be to coat with a high temperature, immersible coating which uses a Silicone Base. Once again, youd need to canvas your local businesses to see who can do it and how much it might cost.

            Mal.

            Comment


            • #21
              Re: Help... Descaling Cimbali M27 & need advice

              Originally posted by 5C514C5F4A0F0C0D3E0 link=1245413520/18#18 date=1245814268
              Can anyone tell me please what this is?  Its out the M27 Start and is one of the first components after the water inlet. Is it ok to put in the acid bath for cleaning?
              If you want to acid wash this fitting (which looks to be a Pressure Control Valve of some kind), you should block all orifices to ensure that no acid gains ingress to the internals, which could cause problems if it did.

              Originally posted by 5C514C5F4A0F0C0D3E0 link=1245413520/18#18 date=1245814268
              Im a bit reluctant to take the top off to have a look inside, as I fear there is a gasket underneath which may be hard to get.
              I wouldnt worry too much about the availability of gaskets Borat. You can get some excellent Silicone based gasket in a tube from places like Repco which do a great job. Looking at the bolts in your photo, they appear to be a Black Steel so if you were to disassemble the fitting, Id give some consideration to replacing them with equivalent stainless jobs....

              Mal.

              Comment


              • #22
                Re: Help... Descaling Cimbali M27 & need advice

                In the end Id already put the pressure reducer in the citric acid but pulled it out after a couple of hours so Im hoping no damage was done.   I opened the top and it turns out there was not gasket there anyway.   Just a big rubber diaphram and a spring with adjusting screw.  Flushed it all clean and it looks ok.

                Also pulled apart the pressure switch and acid bathed the mechanical parts, which as far as I can tell feel like theyre working and still have a solid feel and are moving up and down if gently pushed from the inlet side.

                The boiler was soaking overnight and has cleaned up pretty good, but I might give it one more go to get the last of residual bits of scale off.

                The element is now clean too.  Heres some after pics. Does it matter if any of the prongs (the bits that go in the boiler) are touching?





                Also pulled apart one of the fluid o tech vibratory pumps.  It was dated 00, but for nine years use it was really clean inside with no scale at all.   So put it back together and will leave the other one alone.

                Spoke to Coffex yesterday who recommended the green o-rings for the group heads (rather than the red ones I got from coffeeparts), as the red ones apparently are only good when theyre hot, and leak when theyre cold....

                And the last of the other gaskets and seals should arrive this morning.

                Anyone have a good way to remove the last remnants of old hardened gaskets?   Ive just been scraping it with the back of a knife, then scrubbing with a pot scrubber.

                Comment


                • #23
                  Re: Help... Descaling Cimbali M27 & need advice

                  Originally posted by 4B465B485D181B1A290 link=1245413520/21#21 date=1245891374
                  Does it matter if any of the prongs (the bits that go in the boiler) are touching?
                  Its not a big deal mate but its better if they dont touch as it might create localised hot-spots which will ultimately cause weaknesses. If it is possible to very gently pry them apart so that the individual loops are parallel with each other then thatd be great. If this seems a bit dicey to do then just leave them as is...

                  Looking good now though Borat, everything is coming up really nicely... 8-)

                  Originally posted by 4B465B485D181B1A290 link=1245413520/21#21 date=1245891374
                  Anyone have a good way to remove the last remnants of old hardened gaskets?   Ive just been scraping it with the back of a knife, then scrubbing with a pot scrubber.
                  I just use a small paint scraper (a decent one though, some of the generic ones flex too much and dig in) and have found this to do a great job. If the gaskets are particularly difficult to move, just soak the offending section with the gasket in a some boiling hot water for a while; this should soften them enough to allow easy removal.

                  All the best mate...

                  Mal.

                  Comment

                  Working...
                  X