100 0 1 1 lt 0 5 9 100 100 1 0 lt 0 5 ______________________________________ coupon had green tarnish on surface coupon was clean and shiny tests 1 3 show that low concentrations of butyl benzotriazole with or without the chelant do not inhibit corrosion of the copper alloy tests 6 and 7 indicate that the chelant alone is more aggressive than no chelant at all tests 8 and 9 show that even though very high levels of inhibitor can passivate the metal without chelant an undesirable green tarnish develops in the absence of the chelant in the tests a hardness ion was included so as to stimulate sea water conditions accordingly the na 4 edta concentration was adjusted to take into account demand by the hardness ion on this basis 3 74 ppm of na 4 edta was used for every 1 0 ppm of hardness ion expressed as caco 3 equivalent water conditions were as follows per liter 11 831 g mgso 4 7h 2 o 4800 ppm as caco 3 1 544 g cacl 2 2h 2 o 1050 ppm as caco 3 23 997 g nacl 15 300 ppm total cl 16 2 g na.