evv^Engferid Water Works Association
Vol. XLIX. September, 1935. No. 3.
This Association, as a body, is not responsible for the statements or opinions of any of its members
HSS*4ccc' " REPORT OF COMMITTEE — * ' lilL ^ PIPE LINE FRICTI0N COEFFICIENTS £J ^iJ And Effect of Age Thereon.
[Received July I, 1985.]
Letter of Transmittal.
To the New England Water Works Association,
Gentlemen: On November 8, 1933, the Executive Committee of your Association authorized the formation of a committee to compile information on "Pipe Line Friction Coefficients."
Your Committee sent out numerous questionnaires to obtain data relative to coefficient values and the effect of age and water quality thereon. The accompanying report has been compiled from the information received in these questionnaires and from other available data.
The following general conclusions may be drawn from the data submitted to your Committee:
1. The average actual loss in capacity of tar-coated cast-iron pipe after 30 years of service, based on a total of 473 tests in 19 different systems, was 52 per cent.
The loss predicted in the Williams-Hazen Tables for mains of similar age and diameter (average 20.5 in.) and for "average soft unfiltered river water" is 32.3 per cent.
2. Based upon the data available to the Committee, the Williams-Hazen age-coefficient relation is.applicable primarily to large-diameter mains carrying relatively inactive water.
3. For small-diameter mains carrying active water, the actual loss after 30 years iay be twice the Williams-Hazen predicted loss.
4. Other factors being equal, the data show marked correlation between pH value water carried and rate of capacity loss, average conditions reported indicating for pplies with a pH value of 6.5, twice the loss observed in supplies with a pH value
cope of Revort. The principal objective in preparing this report has *the presentation of heretofore unpublished data upon friction Coefficients of tar-coated cast-iron pipe, with particular reference to the age,-coeflfl$ient relation for this type of pipe and the effect of water quality upofarate*of capacity loss.