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brass alloy vs. bronze in DHW valves

archibald tuttle
archibald tuttle Member Posts: 895
got an alert that a lead free brass valve i was looking at did not have reliable dezincification properties. I'm not sure i ever even remember seeing DZR rating on this stuff before zero lead, with lead having had that important property besides affording better forming/metalworking properties to the alloy.

for my hard water applications i mostly use poly alloy fittings but noone seems to making reliable polyalloy ball valves yet. this seems a little bit of a mystery to me since there perfectly good PVC ball valves, i'm kind of wondering where the poly alloy equivalent is.

Viega, with typical industry leading approach is actually making a 1/2 and 3/4 inch poly valve. haven't had my hands on them yet but of course at present I need 3/8 inch (which veiga makes in ecobrass) and 1 inch which they have started making in Bronze.

well, of course you don't get dezincification in bronze cause it got no zinc. the ecobrass is a C69300 alloy: https://alloys.copper.org/alloy/C69300 also know i believe as silicon brass.

vs. the valve that i got the alloy warning on is C46500: https://alloys.copper.org/alloy/C46500

the key difference in the DZR rated C69300 alloy is higher copper content and small percentage of silicone which is not present in the 46500.

I have had corrosion problems even in the original lead full alloys in systems with relatively acid well water. I don't see as much of the white zinc leaching (but maybe it is there) as I do the green stain evidence that the copper itself has corroded. Iver 10 or 15 years this leads to fittings that drip leak and are fragile and can break off if stressed in these circumstances and the copper piping we replaced 15 years ago had a tendency to manifest pinhole leaks. This isn't a case of high mineral problems (other than in the ground), its rock water off the ledge that manifests natural acid properties.

I don't know that we have that kind of longevity in comparing the presently available alloys and I'd just as soon use poly alloy but its not on the market yet. The bronze valves are cast and cost 3 times as much. So I'm trying to do a cost benefit calculation on paying 3 times as much up front to come back in 24 years instead of 12 (if that is indeed what i'm looking at).

wondering about other's experience and how they are navigating new alloys. and i notice a possibly consequent increase in the offering of stainless fittings as well.




  • hot_rod
    hot_rod Member Posts: 16,818
    for domestic water use or Hydronics? Low ph water is more if the issues. The hard water typically costs the innards of a valve, and protects the brass. Stainless or composite valves are another option.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • archibald tuttle
    archibald tuttle Member Posts: 895
    @hot_rod domestic. composite? i.e.plastic?

    I've been moving all domestic connections over to poly-alloy but very few poly valves available with direct connection. i can get pvc valves and put adapters in them which is extra work and they are bulky so i'm going to call uncle and go with viega 1/2" poly valves off 1/2" 'mains' to this bathroom and then poly 1/2 x 3/8 couplings for my 'last mile'.

    I have yet to see any problems in hydronic service in these buildings and i confess i'm just moving into a water treatment mode. the only notable corrosion problems in 25 years are cast iron pumps in non barrier floor loops. and i cleaned them out and put them back in service.
  • mattmia2
    mattmia2 Member Posts: 5,953
    Don't pvc valves have o-rings which will harden after a decade or 2 and can't be disassembled for replacement?
  • archibald tuttle
    archibald tuttle Member Posts: 895
    mattmia2 said:

    Don't pvc valves have o-rings which will harden after a decade or 2 and can't be disassembled for replacement?

    sorry, missed getting back to this. I've got a PVC valve that froze that I could dismember to analyze the seals. This may well be the case although I've had PVC valves in service still performing well as long or longer than the brass valves that are failing in hard/acid water conditions, so PVC valves may indeed have their own service life problems but looking better than brass at the moment.

    I also haven't reverse engineered these Viega valves that are kind of a late entry poly solution but- as per usual- only available in 1/2 and 3/4 - not that those aren't the most popular sizes but I frequently use 3/8 and 1" as well.