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Readers want information, and they pass along ideas. Ideas Exchange Column i s a careful screening of this correspondence. This i s not a place for praise or criticism; it i s a source of technical questions and their factual answers.
I/EC’s features bring in lots of fan mail.
Paramagnetic Oxygen Analyzers MR. GEORGEEMBER,Research Fellow, Chemical Engineering Debartment, Uniuersit,): of Delaware, Newark, Del. DEARSKR: You have requested information regarding the purchase of a paramagnetic oxygen analyzer for continuously measuring the 0 2 concentration in a gas mixture flowing through the detector with a flow rate of 1 ml. per minute, relating to the article “Magnetic Winds” (I/EC 53, No. 6, p. 62 A). You do not mention the range of analysis required and we are therefore unable to recommend a suitable instrument. ‘The addresses you request are: Waters Associates, Framingham, Mass. Hartman & Braun, Frankfort/Main, Germany, c/o Epic, Inc., 54 Nassau Street, New York 38, N. Y. Siemens & Halske, Aktiengesellschaft, Karlsruhe, Germany, c/o Duffco International Corp., 342 Madison Avenue, New York, N. Y. Servo-Mex Controls, Crowborough, Sussex, England EDITOR
Laminated Wood MR. Yo. T. LEON,KOKSTRUCTOR, P.O. Box 2185, Dlakarta, Indonesia DEARSIK: You have written as follows : “Regarding your article, Laminated Wood (I/EC, July 1961’1 the following questions arise: 1. Are wood species of lesser quality than the West Coast Douglas fir also suitable for making laminates usable in plant construction? 2. Is it necessary to Wolnianize (vacuum pressurr or tank, treatment) before laminating to prevent attack against rot, tropical insects, and especially termites?” The author of the article, Charles W. Masterson, sends us this information : “Regarding the suitability of species for laminating, there is no reason why species other than those used in the United States could not be employed in the laminating process. Density is one of the factors that determines the
gluing ability of a species; so, if basic data on your native species is lacking, it would be necessary to conduct tests of your structural lumber using working stresses assigned to the species to determine the strenqth properties. Because laminated wood structural members are used in systems wherein each member or component must be capable of carrying its full design load, it would be necessary to stress grade the lumber used. The lumber used in our laminated members is kiln-dried to a uniform moisture content range of 10 to 14y0prior to gluing. In an extremely warm, dry climate it might be desirable to dry the lumber to an even lower moisture content. Preservative treatment can be performrd either prior to or following gluing, depending on use requirements and also depending on whether the shape of the member after gluing is such that it can be placed in a commercial retort. An advantage of treating prior to gluing is that penetration of the treatment is obtained throughout the member, while disadvantages of this method are that laminates must be resurfaced after treatment and prior to gluing, which removes the heaviest penetration of the preservative. Treating prior to gluing also results in more waste, higher laminating cost, higher treating cost, and requires great care in the gluing operation to assure a clean glueable surface free of all treating residues. Generally. laminated members are treated after they have been glued, surfaced and fabricated. This also provides better penetration of treatment in areas that have been dapped or treated for connectors.” EDITOR
Pressure Vessel MR. H. SCHAPPERT, Koppers Co., Inc., Plnstzcs Div., Pittsburgh 79, Pa. DEARSIR: You have sent us this interesting communication regarding the article, “Failure of a Thick-Walled Pressure Vessel” (I/EC, July 1961) : “Would it not be safer to use a multilayer vessel in accordance with one of the available methods? In our company, we had a similar experience. A wrapped vessel for 23,000 p.s.i. operating pressure failed when on
the inside wall a scratch developed, caused by a faulty insert. The vessel consisted of a core tube and many layers (wrapped vessel design; Perry’s Handbook, 3rd ed., p. 1243). When the crack reached the first layer, gas escaped through the windings, which could be heard and seen. (The Thereoutside paint peeled off.) fore, we regarded the multilayer vessel as especially safe in this respect, even though the vessel was totally lost.”
About a half scale picture showing the scratch which i s about 1/64 inch deep, and the grooves produced b y the profiled windings
We’re glad no one was hurt. Edward Saibel, author of the article, gave us this opinion: that your question can be answered by neither yes or no. I t depends entirely on the circumstances. EDITOR
Solid Propellants MR. R. 3‘. MACART,SR., Safety Enginrer, Hercules Powder Cn., Magna, Utah
DEARSIR: You write us that the problems of safety with liquid and solid propellants are almost parallel. Also, you wish to know where the information on solid propellants mentioned in the I/EC article [“Handling and Hazards of Propellant Fuels” (hfarch 1961)] is available. The author, H. A. Volz tells us that the information you require is available from Solid Propellant Information Agency, Silver Spring, Md., Manual SPIA-M2, February 1962. However, this is a confidential publication which requires proper security clearance. EDITOR VOL. 53,
NO. 12
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DECEMBER 1961
75A
