Yes, it was the go to. but do you know what 85 triple 5 means? the last 5 means it contains on average 5% Zn.
I am well aware that 85-5-5-5 contains as much as 5% zinc. This alloy however is the most time tested and bullet-proof alloy that has been used for seacocks & thru-hull fittings. About 20 years ago Blake's (European brand) switched away from 85-5-5-5, what they built their reputation on, and went to DZR Brass. I have never once seen an older Blake's seacock dezinced nor have I seen a Spartan, Conbraco or 85-5-5-5 piece made by Groco dezinc. I have however seen newer Blake's and numerous "CR" DZR Brass seacocks dezinced and piles of standard yellow brass dezinced.
the newer DZR alloys contain a lot less Zn.
No they don't. The DZR alloys used by European boat builders contain a LOT more zinc than American seacocks do....
The alloy most used by European boat builders, when they don't use straight brass and unfortunately many do use a standard 60/40 brass, is called DZR brass. DZR Brass/CW602N is 62% Cu - 0.7% Sn, 35.2% Z
n & 2%Pb. The alloy has .7% tin added to aid
in dezincification resistance
being the key word.. 85-5-5-5 has 5% Zn and 5% Sn (tin is what really aids in corrosion resistance) and DZR Brass has 35.2%
Zn and only
The European ISO/RCD essentially allowed or created this move to DZR brass by specifying that a 5 year service life is suitable
. DZR brass is less costly and easier to machine thus the European boat builders love it. If it makes it beyond year five that is all they care about and all it takes to build a boat to meet the ISO/RCD federal laws..
DZR Brass is not more corrosion resistant than 85-5-5-5 bronze, especially not out in the real world... The most proven track record I know of, for any alloy used for seacocks or thru-hulls, is 85-5-5-5 and this is why companies such as Spartan, Groco, Buck Algonquin and Apollo/Conbraco still use it to this day for seacock and thru-hull material. This is most likely because DZR brass would not pass / meet the UL/ABYC corrosion requirements...
85-5-5-5 has many names that get applied to it such as leaded gunmetal, ounce metal, bearing bronze, leaded red brass, tinned bronze etc. but there is no question about its durability in the marine environment. You could not pay me to install DZR on my own boat.
Sometimes we can learn from industry and large classification societies. A look at the shipping classification societies such as DNV (Det Norske Veritas) is but one source. The classification rules for big cargo ships says that a zinc content greater than 30% is not approved for seawater systems. Under DNV classification rules DZR brass "CR" marked seacock or valve or thru-hull/skin fitting would be disallowed but an 85-5-5-5 alloy would be fine.
Under ABS classification (American Bureau of Shipping) no alloy can contain any more than 15% zinc. DZR Brass fails this classification society too but 85-5-5-5 passes.
Under UL1121 any alloy containing more than 15% zinc must undergo an additional "10-Day Moist Ammonia-Air Stress Cracking Test
". At the end of this test there; " shall show no evidence
of cracking or delamination when examined using 25X magnification".. I've not known of any DZR product to pass UL 1121.
The problem, and where all this nonsense started, was the ISO/RCD:
Through-hull fittings for water shall be corrosion resistant, defined as material used for a fitting which, within a service time of five years, does not display any defect that will impair tightness, strength or function."
While DZR is certainly much better than standard yellow brass, what far too many European builders slap into boats, it is NOT 85-5-5-5 in terms of corrosion resistance..
Thanks but I will stick with a proven time tested alloy for my seacocks, and that would be 85-5-5-5....