Handling of Distilled Water in Aluminum H. V. CHURCHILL, Aluminum Research Laboratories, New Kensington, Pa.
A
discussed. Evidence is also PLENTIFUL supply available that another material of satisfactorily p u r e -aluminum-is satisfactory. d i s t i l l e d w a t e r is a necessity in modern chemical APPLICABILITY O F ALUMINUM laboratories. Provision of such a supply entails consideration Except for very special purof the still to be used and the poses the water used in chemical laboratories is once distilled. storage and distribution of the It is apt to contain as much water. as 2 p. p. m. total solids. It Factors involved in the selecis obvious that storage tanks, tion of a still include capacity pipe lines, and accessories must of still, preference as to means have a low susceptibility to atof heating, ease of c l e a n i n g , tack if this limit is not to be maintenance, a n d operation, exceeded. Aluminum has this and, most important of all, the characteristic. quality of distilled water which The applicability of a matethe still will deliver when fed FOR PRODUCTION AND STORAGE rial for a particular use is best FIGURE 1. EQUIPMENT with a v a i l a b l e raw w a t e r . OF DISTILLED WATER established by actually putting This latter factor is often overEach aluminum tank holds 120 gallons, fittings are all aluminum, it to that use and observing looked, although there is adand distilled water is distributed through aluminum pipe lines its performance. Aluminum mittedly a wide variation of has been used to hold and constill performance in handling different types of water. Still operation is an important factor vey distilled water for more than 15 years. Its performance in distilled water quality. The market affords a wide choice is illustrated by the analytical results obtained on periodic of stJills and it is now possible, a t reasonable cost, to pro- samples taken from taps in laboratories of the Aluminum vide laboratories with stills which deliver adequate amounts Research Laboratories at New Kensington, Pa. Illustrative data are offered in Table I. of suitably pure distilled water. TABLEI. DISTILLEDWATERFROM ALUMINUM SYSTEM
STORAGE AND DISTRIBUTION SYSTEM I n planning a distilled water supply, the second step comprises the planning of the storage and distribution system. It is obviously absurd to produce satisfactorily pure distilled water and then contaminate it by improper handling. Consideration of a storage and distribution system a t once raises the question of construction material. A satisfactory material for such purposes is one which is available in a variety of forms, reasonable in price, easy to fabricate and assemble, and, most important of all, which will not objectionably contaminate the distilled water t o be handled. Most of the laboratories of this country handle distilled water in block tin, in tinned copper, or in glass. Piping is usually in block tin, tankage and storage in tinned copper, and storage in glass. There are some shortcomings to all these applications. Block-tin pipe is usually assembled by soldering. Horizontal runs of pipe require support a t close intervals. Glass containers are usually only of the bottle or carboy type and are rarely a permanent part of the storage system. Tinned copper has the disadvantage of being satisfactory only during the life of the tinned coating. An incident occurring a few years ago illustrates one of the hazards of tinned-copper storage tanks. Some aluminum powder had been sold on a specification that it should contain a maximum of 0.04 per cent copper. The customer received the powder and reported a copper content of 0.11 per cent. Investigation revealed the fact that if the customer’s distilled water, in equivalent amount to that used in the analysis of the powder, were acidulated and electrolyzed, copper equivalent to 0.07 per cent in the metal was plated out. Thus there are problems to be solved in handling distilled water, even in what is accepted as standard material today. However, distilled water can be successfully handled in the materials
SAMPLE
DATESAMPLED
TOTAL SOLIDS P. p . m.
ALUMINUM P. p . m.
..a
. .a ..a 0.0087b
0.00~9
0.0i~S 0.0027
0.00!7 0.02:
o.oi2 o.oi:
..
a b
Aluminum not determined. Determined by procedure of Cox, Schwartze, Hann, and Unangst (1).
Spectrographic analyses show that the total residues are principally calcium salts which obviously are derived from still performance. For example, a typical spectrographic analysis of the total solids shown in Table I shows in decreasing order of abundance the presence of the following elements: calcium, magnesium, barium, silicon, aluminum, zinc, iron, copper, sodium, lead, nickel, strontium, silver, fluorine, and tin. The importance of proper operation of stills is often not fully realized. In recent years the dissolved solids in many waters have increased on account of drought or semi-drought conditions. Unless increased bleeding of the still was resorted to, considerable priming occurred and water of poor quality was produced. Many waters tend to form scale readily. This, of course, reduces the efficiency of distillation as regards quantity of output and sometimes lowers quality. The actual performance of distilling apparatus is often overlooked in investigatiohs of distilled water quality and undue
264
July 15, 1933
INDUSTRIAL AND ENGINEERING CHEMISTRY
emphasis is given to the role of the storage and distribution system. The minor character which this latter role sometimes assumes was shown by the examination of a purportedly representative sample of distilled water from the tinnedcopper and block-tin system of a well-known university. This water showed 12.3 p. p. m. total solids. Sodium was the predominant element present. Spectrographic analysis of the residue showed the following elements in decreasing rate of abundance; sodium, tin, calcium, aluminum, copper, iron, silver, nickel, zinc, barium, lead, magnesium, and strontium.
To STORAGE.
265
should be exercised to cut clean smooth threads. Just before assembly all threads should be examined to insure absence of residual cuttings or turnings or other foreign solid material. Competent pipe fitters with experience in assembling other nonferrous piping should have no difficulty in aluminum pipe assemblies. Such work involves the avoidance of drawing up threaded joints too tightly. This is apt either to strip the threads or to cause the metal surfaces to gall or seize. The threads should be accurately engaged and the connection screwed up to the point where the operation entails some difficulty. I n distilled water line assemblies it is suggested that lubricant be used sparingly and that “pipe dope” be not used. After the assembly is complete the line should be placed under a slight vacuum and all joints should be painted with shellac. This will effectively seal all joints but will not subsequently contaminate the water. When the assembly is complete the entire assembly should be flushed out thoroughly with tap water. The entire system should then be filled with distilled water and allowed to stand for a t least 12 hours. The system should then be drained and filled once more with distilled water and allowed to stand for a t least 12 hours and then drained out. The system may then be filled with distilled water for use. Thereafter the system should require no particular attention. The treatment with tap water and the subsequent treatment with distilled water have twofold functions: First, the interior surface is cleaned of all foreign material. Second,
FOR AERATION FIGURE2. DETAILOF ARRANGEMENT OF DISTILLED WATER
Distilled water from a tinned-copper, block-tin, and glass system in an industrial research laboratory showed 1.9 p. p. m. total solids. Spectrographic analysis showed calcium to be the principal element present, with the following elements in order of decreasing abundance: magnesium, sodium, aluminum, copper, silicon, nickel, manganese, zinc, iron, barium, tin, silver, strontium, and chromium. Both of the two latter waters contained more aluminum than water from the aluminum system a t the Aluminum Research Laboratories. With establishment of the fact that handling distilled water in aluminum does not materially contribute impurities to the water, we may pass to other considerations involved in the application of aluminum t o the handling of distilled water. Tanks for the storage of distilled water are formed from sheet. All seams are closed by autogenous welding. Threaded cast-aluminum inlet and outlet fittings are welded to the tank. The tubing and piping used for pipe lines are seamless tube or pipes. Fittings and valves are made of aluminum castings. Table I1 shows the recommended composition of metal for the various forms used. TABLE11. NOMIXAL COMPOSITIOX OF ALUMINUM ALLOYSFOR USE IN DISTILLED WATERSYSTEMS APPLICATION ALLOY^ COMPOSITION^ Storage 2s 99+% A1 Storage 3s 1 25y0 h l n Storage 53s 0.7% Si, 1.25% M g , 0.25% Cr Pipe 2s 99+% AI Pipe 3s 1.25% Mn Pipe 53s 0.7% Si, 1 2 5 % M g , 0.25% C r Connections 43 5% 81 Connections 214 3.75% M g Valves 43 5% Si a Alloy designations are Alcoa alloys of Aluminum Company of America. b All alloys contain normal impurities; iron and silicon with small amounts of other elements.
ASSEMBLY O F ALUMINUM SYSTEM Assembly of the system is usually made by the use of threaded connections, though compression fittings or flanged connections of the Van Stone type are sometimes used. Care
Courtesy, Preciszon Scientific Company
FIGURE 3. ALUMINUM STILL
the aluminum becomes coated with an augmented coating of insoluble aluminum hydroxide which desirably coats the metal surface and eliminates the probability of further attack, even if distilled water of inferior quality is placed in the system. The attack on most metals by water is accelerated by the presence of dissolved oxygen in the water. Aluminum is not one of these metals. It owes its corrosion-resistance to the adherent film of oxide on its surface. The presence of dissolved oxygen acts as a stabilizer of the film. If or when the film is broken or weakened the dissolved oxygen reacts to heal and strengthen the film. While not essential or necessary, it is wise to provide for some aeration of the distilled water supply. One method of accomplishing this may be
266
ANALYTICAL EDITION
seen ih the photograph of the water still and atorage system of the Aluminum Research Laboratories (Figure 1). Figure 2 shows the detail of the arrangement whereby the distilled water discharged from the still condenser drops through air for a few inches before entering the storage system. Additional evidence as to the satisfactory character of distilled water handled in aluminum svstems is derived from an examination of blank determinatik run in connection with analyses for RzO, content. These blank determinations in the Aluminum Research Laboratories, which cover all reagents including distilled water used in analyzing the sample, never exceed 0,001 gram of RzOs.
Vol. 5, No. 4
CONCLUSIONS The usefulness of aluminum for handling distilled water is shown by the fact that it does not seriously distilled water, it is available in a variety of wrought and cast forms, it is easy to erect and assemble, and the system may be easily disassembled in such procedure is de&
-,
aoie.
LITERATURE CITED (1) Cox, Schwartse, Hann, and Unangat, IND. ENQ.CHEM.,24, 403
(1932).
RECE~IVED March 24, 1933.
A Convenient, Inexpensive Water-Motor Stirrer RALPHE. DUNBAR,Madison, Wis.
S
OME elementary knowledge and experience in glassblowing is desirable in constructing this motor stirrer. Two glass side arms B and C are attached to a 125- or 150-ml. Erlenmeyer flask A . The flask is closed with a one-hole rubber stopper carrying an arrangement of small glass tubing, similar to the familiar mercury seal, as illustrated at D. The
glass stirring rod, extending through this stopper and seal, has a small stopper G attached to the upper end. This stopper G has inserted in slits in its upper portion small vanes of metal made of copper, aluminum, or similar metal, crossing a t right angles as illustrated a t F. A small glass jet E is introduced through the side arm a t B, and held in place by a short length of rubber tubing. Suitable lengths of laboratory rubber tubing connected a t B and C are added to carry the water to and from the flask. This entire arrangement is vividly shown in Figure 1. Figure 2 shows an end view from above of the arrangement of this jet E and the vanes for driving the stirrer. This stirrer is clamped to a ring stand with small laboratory clamp with the flask in an inverted position as shown, when it is to be used. The stirrer is put in motion by merely introducing a stream of water from the usual laboratory outlet through the jet E. The waste water leaves the flask through C. It is desirable to have the outlet C larger than the intake at B to prevent the unnecessary accumulation of water within the flask. This stirrer will be found especially convenient for melting point baths and similar small containers. It may also be used with the usual organic reaction vessel or flask, even where it is necessary to attach an additional mercury seal at the mouth of the second reaction flask. I n case it is not convenient to attach the two side arms B and C to the small Erlenmeyer flask as illustrated in Figure 1, a three-hole rubber stopper may be substituted as illustrated in Figure 3. The stream of water enters through K and leaves through H . Otherwise the arrangement is the same. A wide-mouthed flask will permit a larger and more efficient type of construction in either case than the usual narrowmouthed Erlenmeyer flask. I n the type of construction illustrated in Figure 3 even a small wide-mouthed bottle may be used. R E C E I ~ EApril D 19, 1933.
CAMPHOR.Approximately 60 per cent of the cam hor duced in Japan during 1931 and 1932 came from tKe ISK;~ of Taiwan (Formosa), and the remaining 40 per cent originated in Japan proger, chiefly in the Island of Kyushu, according t o information made available by the Department of Commerce. During the year ended March 31, 1931, the total production of crude camphor amounted to 4,585,568 pounds. In the following year the output dropped to 3,544,997 pounds. Camphor oil production totaled 17,275,246 pounds during the fiscal year 1930-31, and 15,921,621 pounds during the fiscal year 1931-32, the percentages of origin being the same as those of crude camphor. Taiwan supplied a greater quantity of natural crude and re-
fined camphor to Japan in the calendar year 1932 than in the preceding year, although the value declined markedly. Camphor oil also was obtained in larger amounts. Exports from Taiwan to Japan follow: camphor, 1931, 3,008,507 pounds; 1932, 3,138,202 pounds; camphor oil, 1931, 7,237,701 pounds; 1932, 8,403,116 pounds. Exports of camphor direct from Taiwan to the United States declined from 1,814,918 pounds in 1931 to 1,483,360 pounds in 1932, while shipments to other countries gained from 299,820 pounds to 580,346 pounds, respectively. Increased exports of camphor from Japan proper occurred in 1932, the total amounting t o 3,107,287 pounds, compared with 2,783,615 pounds in 1931. Shipments to the United States declined.
