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I’ Sewage Effluent
Manometer and Pressure Data
DEARMR. POWELL: Your discussion on Industrial Wastes, published in January 1956 issue of I&EC, was interesting. One subject upon which me have seen very little information is that describing the use of sewage effluent for industrial cooling systems and boiler plants. Can you suggest books, articles, or publications which discuss this application? Perhaps you may be able to refer us to companies who are using this approach.
DEAR M R . PIERCE: I n your Equipment and Design column (I&EC, September 1955) you stated that lowering the downstream pressure has no further effect on the flow of gas through a n orifice once the critical pressure ratio has been reached. This is true for a venturi or for a well-rounded orifice, but for a sharp-edged orifice, the mass rate of flow continues to increase as the downstream pressure is reduced. Data presented by R. G. Cunningham, Trans. ASME, July 1951, show that the mass flow rate increases by about lOy0 as the downstream pressure is lowered from 0.5 to 0.1 times the upstream pressure. M7e have observed the same effect in our studies a t Cornell. This does not mean that sonic velocity is exceeded at the orifice. A t the critical pressure ratio, sonic velocity may be reached a t the vena contracta, but the velocity through the orifice is much Jess, since the pressure is greater and the flow area greater a t the orifice than at the vena contracts. As the pressure is lowered further, the vena contracta moves towards the orifice and increases in area. Sonic velocity still exists a t the vena contracta, but its increased cross section means a greater weight rate of flow through the orifice. The linear velocity through the orifice (at the sharp edge of the orifice) increases, but it is still Iess than the sonic velocity.
R. H. GILLES Continental Products of Texas Odessa, Tex.
MR. POWELL’S -4NSWER: I n answer to your request for references on industrial uses of sewage effluent] I suggest the following: (1) Waste Water Reclamation and Utili-
zation, California State Water Pollution Control Board Publication No. 9, 1954. (2) Direct Ctilization of Waste Waters, California State Water Pollution Control Board Publication No. 12, 1955. (3) Industrial Use of Reclaimed Sewage
Water a t Amarillo, M. C. Nichols, Sewage and Industrial Wastes, January 1955. Wastes Column, S . T. Powell, IND.ENO.CHEM.46, 91A, (July 1954). (Reprint enclosed).
(4) Industrial
I expect to present a paper on this subject at the forthcoming meeting of the American Chemical Society in Dallas, Tex., during the week of April 8-13] 1956. You may wish to attend this meeting, which will include a symposium on Re-use of Water by Industry, to be held by the Division of Water, Sewage, and Sanitation Chemistry of the Society. You may obtain the first two references listed above by writing to Vinton W. Bacon, Executive Officer, Calif, State V7ater Pollution Control Board, Sacramento, Calif. 54 A
PETERHARRIOTT College of Engineering Cornel1 University Ithaca, IT.1‘.
MR.PIERCE’S ANSWER: I am glad to have the information about the difference between the sharp-edged and the well-rounded orifice in the effect on rate of flow a t super-critical ratios. Your explanation makes clear the reason for this phenomenon.
INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 48, No. 4
New polymer offers rubber industry important improvements particularly valuable when compounding synthetics. I t has demonstrated exceptional qualities as a mold release; as a lubricant it allows higher operational speeds. Compatible with Natural and Synthetic Elastomers
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technical data is available in an eight-page brochure. Samples of A-C POLYETHYLENE are also vours for the askiig. CHEMICAL PROGRESS
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r-------SEMET-SOLVAY PETROCHEMICAL DIVISION I I I I
Allied Chemical & Dye Corporation Room 570 40 Rector Street, New York 6, N. 1.
Please send me 0 literature
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0 samples of A-C POLYETEYLENE
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April 1956
INDUSTRIAL AND ENGINEERING CHEMISTRY
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