INDUSTRIAL AND ENGINEERING CHEMISTR’S:
542
what constitutes “thermal equilibrium” when testing a t 210’ F. and the use of a standardized oil has eliminated a great deal of trouble. A parallel procedure when adjusting bath temperatures for tests a t 210’ F. with the Saybolt One Fifteen viscometer is to use a n oil of known kinematic viscosity. I t is, however, desirable t h a t the Saybolt One Fifteen outflow time, as certified from a n authoritative source, should also be known. The reason for this has been indicated in the discussion of variations between experimental and calculated values listed in Table I. I n many instances i t probably will be desirable to operate Saybolt One Fifteen tubes in multiple-unit thermostattic baths in which one or more Universal tubes are also installed. I n such cases i t is practical to adjust the bath temperature so that the Saybolt Universal tube (or tubes) gives the correct values with a standard oil such as A. P. I. Beta. This was done in the tests which are represented by data listed in Table I. If extreme accuracy is required, account must be taken of the deviations of the tubes from normal outflow time as determined by direct comparison with standardized tubes. The one respect in which the One Fifteen instrument seems to be less reliabIe than the Universal is that on occasions its results show poor repeatability. This has been found to be due to excessive dust in the air of the room where tests are conducted. Dust particles, if stirred into the oil and temporarily or permanently lodged in the outflow tube, are capable of causing greater deviations with the One Fifteen than in the wider orifice of the Universal. This trouble rarely occurs without being noticed and can usually be eliminated by maintaining a proper degree of cleanliness in the laboratory. It is sometimes necessary to keep windows and doors closed if the outside air is heavily laden with dust. The Saybolt One Fifteen viscometer is not a complete sub stitute for long-capillary glass instruments such as are gen-
VOL. 12, NO. 9
erally employed for determining kinematic viscosity. There are, however, many laboratories which cannot as yet employ the latter type of instrument advantageously but which are now using the Saybolt Universal and can install and use One Fifteen tubes to good advantage. The accuracy of their determinations in the low viscosity range will be improved and the necessity of purchasing additional accessories or training operators in new technique will be avoided.
Availability Assurance has been obtained that a t least one manufacturer of oil testing instruments will produce and sell Saybolt One Fifteen tubes if a commercial demand develops. The authors are prepared to assist other manufacturers in establishing calibration standards and in obtaining working tables and certified calibration oils for distribution to customers.
Acknowledgment The invaluable assistance rendered by W. H. Schaer, instrument maker in the laboratory of the authors, is hereby acknowledged.
Literature Cited Am. Sot. Testing Materials, Standard Method for Conversion of Kinematic Viscosity to Saybolt Universal Viscosity, Designation D 446-39. Am. SOC.Testing Materials, Standard Method of Test for Viscosity by Means of Saybolt Viscometer, Designation
D88-38.
Am. SOC.Testing Materials, Tentative Method of Test for Kinematic Viscosity, Designation D445-3YT. Dean, E. W., Bur. Mines, Repts. Investigations 2215 (February, 1921). Herschel, W. H., Bur. Standards, Tech. Paper 112, (June 27, 1918).
Saybolt, J. TV. (his son), private communication
Slide Rule for Water Technology Calculations A. ADLER HIRSCH State Department of Education, Baton Rouge, La.
A
S P E C I A L slide rule with arithmetic divisions spaced inversely according to the calcium carbonate equivalent weights of the various components solves directly various water technology calculations involving concentration eonversions, equivalents, ionic balances, and chemical dosage. By certain artifices i t furnishes close approximations to a diversity of other water chemistry problems which depend on first degree equations. Kinetee11 applications are listed. Ten scales are provided as shown. On the top stock are drawn transruled scales for converting grains per gallon and pounds per million gallons, and also an A scale Khich functions dually for parts per million conversions and for alkalinity as calcium carbonate. Along the edges of the slide proper two split scales represent the chloride and sulfate anions and the calcium and magnesium cations, each pair of segments being numbered in opposite directions from an internal zero point to minimize manipulations. Scales for sodium, theoretical lime (90 per cent calcium oxide), and soda ash (95 per cent sodium carbonate) dosages are on the bottom stock.
Direct Applications The following types of problems may be solved directly or greatly abridged ; the corresponding slide-rule operations are indicated briefly in parentheses. A. Problems solved by direct alignment 1. Conversion of concentration units (align scales in-
volved) 2. Determination of calcium carbonate equivalents (align
quantity with A scale) 3. Lime dosage (align equivalents on A scale with 4. Soda ash dosage dosage scale)
1
B. Ionic sums solved by direct addition 5. Calculation of hardness from analysis (read calcium and magnesium on A scale) 6. Total milligram equivalent concentration (summation of anions or cations in p. p. m. on A scale i 50) 7. Character formulation (application of above) 8. Calculation of sodium by balancing ions (see example) 9. Hypothetical compounds (successive distribution of
residua)
10. Ionic strength (successive addition of monovalent ions as p. p. m. of calcium carbonate plus 4 times bivalent ions, all + 200,000)
EXAXPLE.Calculation of sodium by balancing ions. This procedure, involving mechanical addition followed by subtrac-
SEPTEMBER 15, 1940 tion, is the specific purpose for which the slide rule was originally designed. Computation time is reduced to a matter of seconds. Assume a surface water of the following ionic composition: Anion
Cation
P. p . m. Alkalinity as CaCOs
P. p . m.
07 42
so4 c1
Ca
38
M g
8 18
Na
16
Solution for undetermined sodium. Opposite 97 on the A scale set 16 on the Cl scale, then move the glass to 42 on the SO4 scale. Under the glass now set 8 on the Mg scale; opposite 38 on the Ca scale read the required answer, 16, on the Na scale.
Approximations Problems which may be quickly approximated by special artifices include : -4. Dosage and other problems solved by substituting scales to obtain proper ratios 1. Sulfuric acid to reduce carbonates (carbonate reduction on A ; read sulfuric acid on SO4 scale, with -2 per cent error) 2 . Theoretical sodium sulfite for oxygen removal (set dissolved oxygen X 10 on A , note SOa; reset to this value on A , read pounds per million gallons +- 100, shows 1.5 per cent excess) 3. Sodium sulfoglucosate ( 2 ) for oxygen removal (set dissolved oxy en X 100 on pounds per million gallons, read without error) 4. Calgon ( 3 ) sequestration (10 X C1 reading matched against hardness on SO4; gives 1 per cent excess) 5. Amount of boiler scale ( 6 ) , pounds per 1000 gallons (add components: suspended solids, set on A , read pounds er million gallons + 1000; p. p. m. Mg set on ~ 1 read‘s04 , i 100, error is 2 per cent; p. p. m. Ca set on A , read Mg +- 100, with 1 per cent error) B. Miscellaneous problems 6. A. S. T. M. ratio (estimate ratio of SO4 value set on C1 scale to alkalinity on A ) 7. Soap waste cost (6) (set the central index opposite 11 on A , opposite hardness on so4 read cost, cents per 1000 gallons, on A ) 8. Quality of irrigation water ( 4 ) (type of alkali immediately identified from equivalents; quality determined from a procedure based on reciprocals of the alkali coefficient) 9. Electrical conductivity (see example) EXAMPLE. Electrical conductivity calculation. The formula of Gustafson and Behrman (1) may be recast for purpose of slide rule approximation to read : noncarbonate anions as p. p. m. CaC03 0.744 alkalinity Conductivity mho ( X lo5) = 4 Since equivalent C1 = 0.71 alkalinity, there follows with 4 per cent maximum error: noncarbonate anions as p. p. m. CaC02on C1 scale D. D. m. aikalinity on A‘sdale Conductivity mho ( x los) = on C1 scale 4 To find the conductivity of the water sample, first determine the equivalent anion concentration (165 p. p. m.); by difference, noncarbonate anions are 68 p. p. m. Set 68/4 on the C1 scale opposite 97/4 on A and read 35 mho conductivity ( X lo5) on C1 at the left margin of the stock.
.f
+
+
Literature Cited (1) Gustafson, H., and Behrman, A. S., IWD.E m . CHEM.,h n a l . Ed., 11, 355 (1930). (2) Haering, D. W., “Organic Methods of Scale and Corrosion Control”, 2nd ed., p. 13, Chicago, D. W. Haering & Co., 1938. (3) Hall, R. E., and Jackson, H. A., U. S. P a t e n t 1,903,041 (1933). (4) Rogers, rillen, “Manual of Industrial Chemistry”. 3rd ed., p. 72, New York, D. Van Nostrand Co., 1920. ( 5 ) Ibid., p. 62. (6) Whipple, G. C., “Value of Pure Water”, pp. 24-8, New York, John Wiley Bi Sons, 1907. PRZSENTED before the Division of m‘ater, Sewage, and Sanitation Chemistry a t the 99th Meeting of the American Chemical Society. Cincinnati. Ohio
