Effect of Solutions of Filter Alum on Brass Pipe and Fittings

Abstract

In 1906 the Hackensack Water Company installed a line of 2-inch standard seamless brass pipe to convey alum solution from the application tank to the dosing point, 170 feet distant. The line was made up with standard heavy pattern brass fittings and had a 2-inch connection through which water at 80 pounds pressure could be supplied for flushing purposes. The average rate of flow through this pipe was 7J gallons per minute, corresponding to 43 linear feet per minute. Considerable trouble from plugging was experienced and as time went on it became necessary to flush the pipe more and more frequently. Leaks developed at the joints occasionally and sections of the line were removed, threads recut, new fittings supplied, and short pieces inserted to make up the length. This continued until October 1910, when it was found that the pipe was getting too thin to be rethreaded successfully and the line was removed and scrapped. At this time there was a hard yellow deposit in the pipe, uniformly i inch thick, which had cut down the available flow to less than 10 gallons per minute. During 1906 and 1907, 4 per cent solutions had been used much of the time, with periods when the strength had been increased to 6 per cent. During 1908, 1909 and 1910, 6 per cent solutions were the rule with occasional resort to 8 per cent strength. This 2-inch pipe weighed 48 pounds per length of 12 feet when installed in 1906 and 31 pounds per length when discarded in 1910.