Equipment and Supplies: Sediment laboratory analyses--Visual-accumulation-tube charts



In Reply Refer To:                         September 8, 1980
EGS-Mail Stop 412


QUALITY OF WATER TECHNICAL MEMORANDUM NO. 80.24

Subject: Equipment and Supplies: Sediment laboratory analyses--
         Visual-accumulation-tube charts

It has been brought to our attention that the 120-cm VA-tube 
charts being supplied by Headquarters, Form 9-265i (Rev. 
2-67), have a scale distortion that can result in errors, 
particularly for the 62.5 um size. The errors are greatest 
above the 30 degree temperature line.

If you have Form 9-265i 120-cm charts that show (Rev. 10-62) 
in the upper left hand corner, these should be used instead of 
the 1967 revision. Even the 1962 revision appears to have some 
distortion. If you have only the 1967 charts, you are urged to 
contact the Sedimentation Project (FTS 725-2218) to order a 
small supply until we can obtain better charts to stock in 
Reston. In order to minimize errors you should not analyze 
samples at water temperatures greater than 25 degrees C.



                         R. J. Pickering
                         Chief, Quality of Water Branch

WRD Distribution: A, B, FO, PO