Table I.
Diffusive Losses to the Walls of a Circular Tube
-
-_C Q , Liters/Min.
5
SO
IO0
d, Cm.
1.5 2.5 10 15 1.5 2.5 10 15 1.5 2.5 10
15 130
1.5 2.5 10 15
Re 410 240 65 41 0
2400 650 410 .... 4700 1300 830 ....
.... 1900 1200
1 0.29 0.29 0.29 0.29 .... .... 0.028 0.028
.... .... 0.014 0.014
.... .... 0.0 1 0.01
c,
0.01 0.01 0.01 0.0 I ....
....
0.5 0.5
.... .... 0.7 0.7
.... .... 0.8 0.8
"Mociel indpplicnble owing to high Re and turbulent flow.
atmosphere to the point of instrumental analysis. Such sampling ducts can be made of inexpensive materials such as aluniinuni irrigation conduit which provides adequate structural strength to stand unsupported for a considerable height. A sampling system of this sort has been used for
over a year at the University of Washington. A n inexpensive blower is used to maintain the airflow. Not only is such a metal intake easier to construct than a glass system. but also has the following advantages: A 15-cni. pipe can be cleaned easily by pulling a cloth through it with a string, Sampling ports can be cut into the pipe at any location and. if unused, can be plugged with stoppers. Metal poses no breakage hazard. The pipe does not have to be clean to provide a representative sample, as is the case with smaller tubes. It is unnecessary to use a supposedly inert material by proper choice of size and flow rate. In fact, it seems unlikely that an inert material surface could be maintained in a real operation. Glass or appropriate plastic lines can be run from the main duct a short distance to individual instruments. These lines are easily observed and cleaned. If instruments are grouped closely around the inlet duct, diffusive losses can be minimized. Litelntrrie Cited Davies. C.N.. Aerosol Science, Academic Press, London, 1966. Yamada, Victor M., M.S.-Ch.E. thesis, University of Washington, Seattle. Wash., 1968. Recei1,erl for rebsiew September 27, 1968. Accepted January 31, 1969. Thir work was supported by Training Grant TOI-AP 00029-04 f r o m the National Air Pollution Control A clminirtration.
Correction
Correction
APPLICATION OF INTERNAL REFLECTANCE SPECTROSCOPY TO WATER POLLUTION ANALYSES
SULFUR HEXAFLUORIDE AS A GAS-AIR TRACER
I n this article by J. S. Mattson and H. B. Mark, Jr. [ENVIRON. S a . TECHNOL. 3, 161(1969)], on page 161 the relation should I'K(X), and on page 163, the caption for read n(X)V(X)(l 3400 to 3200 cm.-' 0-H; 2900 Figure 4 should read cm.-' C-H; 2300 cm.-' G = N ; 1650 crn.-l C=O; 1350 cm.-1 C-H. IRS crystal was KRS-5. 484 Environmental Science & Technolog?
In this article by Turk et al. [ENVIRON. SCI. TECHNOL. 2, 44 (1968)], on page 47, 2nd column, 5th line under subheading Meteorological Conditions. the phrase , , , there being no temperature change with elevation should read . , . there being no potential temperature with elevation-i.e.. an adiabatic lapse rate.
