Mix stainless/brass or use brass w/lead?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by joseph skoler, Apr 9, 2021.

  1. joseph skoler

    joseph skoler Member

    Joined:
    Jan 14, 2018
    Location:
    Sullivan County, NY
    I’m building a manifold with 2” brass pipe and tees for a single family home.

    The first tap is 1.5” for fire suppression.

    After the first tap code requires a solenoid valve.

    I need to choose between a brass valve that has lead or a stainless valve.

    I’m concerned about the lead and I’m concerned about corrosion from mixing the stainless and brass.

    Which would be a wiser choice? Or is there a third option?

    Thanks!
     
    Last edited: Apr 9, 2021
  2. wwhitney

    wwhitney Well-Known Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    Is the solenoid valve for a system that shuts off domestic demand when one of the sprinklers goes off, to ensure sufficient supply to the fire sprinklers?

    If so, have you considered a passive valve that does the same thing? E.g.

    https://www.tyco-fire.com/index.php?P=detailprod&S=9800

    Cheers, Wayne
     
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  4. joseph skoler

    joseph skoler Member

    Joined:
    Jan 14, 2018
    Location:
    Sullivan County, NY
    I think that would be a great solution but it the DN50 (2”) well over $1.100

    ugh.
     
  5. wwhitney

    wwhitney Well-Known Member

    Joined:
    Mar 17, 2019
    Location:
    Berkeley, CA
    Well, the simplicity and fewer parts to install must yield some significant labor savings, so I bet it would pencil out. What's the power source for the solenoid, and is it required to activate during a power failure, and does that mean you have to provide backup power?

    Cheers, Wayne
     
  6. joseph skoler

    joseph skoler Member

    Joined:
    Jan 14, 2018
    Location:
    Sullivan County, NY
    At over 4x the cost, I'm not sure it works out.

    But I really don't know the full analysis. I don't know the controls necessary to operate the solenoid -- maybe that will make a difference.

    Waiting to hear back from fire suppression company.

    Thanks!
     
  7. Jeff H Young

    Jeff H Young In the Trades

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    I don't know how your area is? but a valve with lead isn't an option in domestic water here so that would narrow down your choice
     
  8. joseph skoler

    joseph skoler Member

    Joined:
    Jan 14, 2018
    Location:
    Sullivan County, NY
    I don't know what the rules are here about a valve with lead.

    Would you be concerned about a stainless valve with brass pipes on each side?
     
  9. gsmith22

    gsmith22 Active Member

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    May 2, 2019
    Location:
    Central NJ
    any two metals in direct contact with an electrolyte will cause galvanic corrosion to the less noble (anode) of the two. This is true whether it is titanium touching gold (both very noble metals and not generally prone to corrosion) as well as magnesium (least noble) touching gold (very noble). The difference will be the rate of corrosion. Gold is unlikely to cause titanium to corrode in our lifetimes. Magnesium will corrode touching gold damn near instantaneous by comparison. So, generally if you mix metals, you want them as close together on the galvanic series chart as possible and likely need to keep their difference in relative voltages close (less than 0.2V). Brass is typically around -0.35V and stainless (at least 304) would be around -0.08V (316 would be more like -0.05V). So that is above the 0.2V difference suggesting the stainless will corrode the brass. In practice, this may not be true due to area considerations (like maybe lots more copper/brass than stainless in the whole system) and maybe the water has low TDS so not a very good electrolyte. I would generally say don't attach brass to stainless as you should expect some corrosion of the brass. Not sure how they are connected but maybe you can wrap the threads with lots of tape so there is very little actual physical contact? Any way to put plastic between them?
     
  10. joseph skoler

    joseph skoler Member

    Joined:
    Jan 14, 2018
    Location:
    Sullivan County, NY
    On the advice of people who know far more than I do, I tape and dope all threaded connections. It sounds like that will reduce the galvanic corrosion some amount.

    Further, as you suggest, this will be the only stainless in the system (the rest of Poly, Brass and Pex), so that, too, should reduce the corrosion.

    The manufacturer told me that the body is 304 and the internals are 316 -- so the internals would have a greater voltage difference.

    I don't know where this leaves me.
     
  11. gsmith22

    gsmith22 Active Member

    Joined:
    May 2, 2019
    Location:
    Central NJ
    Remember, galvanic corrosion is always about direct contact because an electrical circuit is being formed. For the area aspect of galvanic corrosion, its the areas of the two parts in contact that matter. So stainless fitting attached to brass tank likely won't cause corrosion of the brass tank. Brass fitting attached to stainless tank and the brass fitting likely gets attacked.

    i would probably use the stainless part as putting something not certified as lead free in a domestic water line could likely invite far more problems (perceived or actual who knows). 316 is more noble than 304 but remember, its only the metals in contact so 304 is your noble metal comparison with the brass. I would probably set up the plumbing so the brass parts that would be in direct contact with the stainless part could be changed out relatively easily in the future (threaded connections, unions, etc.). This way, if it turns out that galvanic corrosion is an issue, at least the repair gets minimized. Did you consider stainless fittings/pipe for making up this manifold before switchover to pex?

    https://www.supplyhouse.com/T304-Stainless-Steel-Fittings-20603000

    https://www.supplyhouse.com/Stainless-Steel-Nipples-20480000
     
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