158
INDUSTRIAL A N D ENGINEERING CHEMISTRY
Vol. 17, No. 3
CONCLUSION
Table II. Determination of Portland Cement Cement NO.
% Cement per MI. of 0.5 N HCI
Hydrated cement 2.88 2.94
Dry aeinenf 3.70 3.84 3.52 3.32 3.15
2.71
2.55 2.42
Many methods have been suggested and tried with varying success. The authors have evolved a method which is simple and considerably faster than any method described in the literature. While this method is not extremely accurate, and blanks of the soil and the cement used are desirable, it is accurate enough for most practical purposes. ACKNOWLEDGMENTS
SUPPLEMENTAL INVESTIGATION
Inasmuch as both soil-cement mixes and cement-contaminated mu& would probably contain hydrated cement, it was thought necessary to check the volumetric method using five hydrated cements. Neat cement slurries were allowed to set with an excess of water present. A sample was then taken and the per cent cement determined using the p H meter variation. Using a 1.000gram sample the results reported in Table I1 were obtained. This is as was expected, since hydrated cement has taken on water and contains less than 65y0 calcium oxide. Hence, hydrated samples must be checked against hydrated cement blanks when necessary.
lass-Surfaced
The authors desire to thank the Halliburton Oil Well Cementing Company, under whose auspices this work was accomplished, for permission to publish. They also desire to thank the following pmons for their help, criticism, and suggestions during the investigation: S. S. S.Westbrook, Halliburton Field Laboratory; M. E. Prout; F. M. Anderson, Halliburton Lahoratory; Hayden Roberts, Halliburton Lahoratory Director; and the many others who aided a t vs~riorioustimes. LITERATURE CITED (1) Am.Soc.TestinpMateri~*,A.S.T.M. Standards,Part 11, C85-42.
p. 385,1942.
agnetic Pump
For Circulating Liquids in a High-Vacuum System G. D. OLIVER, W. G. BICKFORD, S. S. TODD, AND P. J. FYNN Southern Regional Research Laborstory, New Orleans, La. N CONNECTION with the cireulstion of fats and oils in a large cyclic falling-film molecular still (I), a pump was designed to meet the following principal requirements: to operate in a system whose pressure may be as low as 10-6 to 10-6 mm. of mercury, to avoid contamination of the cycled fluid, to have no dead spaces that keep portions of the liquid from circulating, to pump automatically several hundred milliliters of liquid per minute, and to drain by gravity and be easily cleaned. Several pumps with various types of valves have been described in the literature, but none was found that would meet all requirements satisfactorily. A pump having II hollow plunger and ball-and-tail valves was used by Quackenhush and Steenhock (4)on a new molecular still, but i t had insufficient pumping capacity to meet requirements. A pump of earlier model having a hollow plunger and ball valves has been described by Hickman (S)and by Kosenberger (6). Other pumps, more complex in design,are difficult to operate in a high vacuum and may contaminate the cycled liquids. A complete spparatus designed to fill the above requirements is illustrated in Figure 1. In general, i t may be used to pump any liquid noncorrosive to glass against a considerable head The all-glass-surfaced pump, B, is a singleacting type employing electromagnets to operate % solid piston. Thepalves are very sensitive and permit a yolume efficie~cyfor the pump of 95% based on a measured delivery of 17 ml. per stroke a t a rate of 255 mi. per minute. The holdup in the entire pumping unit is very small, since the liquid in the pump after each stroke is relatively negligible. The pump is automatically operated, and its speed is controlled through an eddy-current flasher motor, C (flasher motor 3-6172, Sangmno Electric Company, Springfield, Ill.). Hand switches, shown below C , may also he used to operate the pump. By a simple adjustment of the flasher motor and proper spacing of the ‘solenoids,the length of a stroke of the plunger and the retio of the time of its upward to its downward stroke may be set for the highest pumping efficiency. The 4-tube rectifier, A , shown in Figure 1is used as a directcurrent power supply for the solenoids. The construction of the pump is shown in detail in Figure 2.
The plunger, P , was made from a glass tube which was ground together with the glass cylinder of the pump in a manner that permitted free and smooth movement of the one inside the other. A mild steel rod, J , was sealed inside the plunger shell together with a small piece of ashestos at each end to bold the rod firmly in place. The book, If, on top of the plunger may be used to remove i t from the pump through the large ground-glms joint, B . The plunger is approiimately 2 cm. in diameter, 11.5 cm. long, exclusive of the hook, and weighs 160 grams complete. A depression, F, a t the bottom of the cylinder of the pump, holds a woven fiber-glass cord, G, to cushion the fall of the piston when the pump is empty.
Figure 1. Solenoid Pump and Accessory Apparatus
ANALYTICAL EDITION
March, 1945
The side arm, A connects the intake to the pump cylinder a t a point just below the maximum height reached by the top of the plunger in its upstroke. This arrangement permits any liquid that leaks by the plunger during pumping to return directly to the intake for repumping and at the same time relieves the back pressure on the plunger. The two valves, Vl and V 2 ,control the flow of the liquid through the pump. Each valve is composed of a ground-glass plate, D,approximately 1 mm. thick, which makes contact with the ground end of a tube projecting into the valve chamber, C. The side wall of the valve chamber is indented in three places in order to keep the ground-glass plate in a vertical position close to the end of the projecting tube, so that proper valve action may be attained. The valves are tilted slightly from the horizontal to facilitate the draining of the pump and connecting lines through the stopcock, E. Three direct current solenoids, 81-3 (Cutler-Hammer coils Kos. 9, 91, 55, 115-volt direct current, Cutler-Hammer, Inc., Detroit, Mich.), spaced to give the desired stroke, are used to operate the plunger. SIraises the plunger and holds it until the pump cylinder is filled, then is automatically removed from the circuit by the flasher. Simultaneously, S2 and Sa,connected in parallel, are energized and pull the plunger on the downward pumping stroke. The speed of the flasher motor, through which the direct current to the solenoids is controlled, may be varied when necessary to give a range of 7 to 30 complete pumping cycles per minute. The best pumping cycle allows the barrel of the pump just enough time to fill, following the practically instantaneous upstroke and prior to the beginnin of the downward stroke. The time for a complete cycle of &e piston, when a vegetable oil a t 50' C. wm pumped t h o u h an 8-mm. tube to a reservoir a proximately 240 cm. (8 feet? above the valves, was 4 seconds. !'he 4-second cycle may be divided into 2.5 seconds for the upstroke and filling of the pump, and 1.5 seconds for the downward stroke.
B"
159
T
)01 E"
Figure 3.
Circuit Diagram for
866 Bridge Rectifier
FI. Fuse 1 rmparc FY. FW' 3 amperes TI,Tt. ~ikaenllrandormer,9.5 volb, 5 amperes Thodamn T19F88 Ta. Filament lranrlormer, 2.5 volb, 1 0 amperes, fhordmon T19F
The bridge network was chosen in preference to other rectifier circuits because of its simplicity, and because there were aveilable no commercially built transformers that could supply 500 milliamperes a t 150 to 200 volts after rectification. This type of rectifier has the advantage of developing an average direct current voltage that is nearly 90% of the effective alternating current input voltage, when the voltage drop through the tube is disregarded. I n the application described, the plates of the tubes were supplied with 208 volts alternating current from the laboratory line. The average direct current voltage developed by the rectifier was 160 volts. The network can easily supply 500 milliamperes, and has given entirely satisfactory service during more than a year of operation. A voltage-doubler circuit (3) operating from a 117-volt alternating current supply might prove practical as a power source for the pump in laboratories having no 208-volt line. LITERATURE CITED
(1) Detwiler, S. B., Jr., and Markley, K. S., IND. ENG. CHEM., ANAL.ED.,12,348-50 (1940). (2) Hickman, K. C. D., IND.ENG.CHEM.,29, 966-75 (1937),especially p. 968. (3) Hitchcock, R. C.,Eleclronic~, 17, [NO. 21, 102 (1944). (4) Quackenbush, F. W., and Steenbock, H., IND. ENG. CHEM., ANAL.ED., 15,468-70 (1943). (5) Rosenberger, Reins, Science, 71, 463-4 (1930).
Figure 2.
Detail of Pump Construction
The pump valves and connecting lines may be wrapped with resistance wire in order to heat the more viscous liquids, like hydrogenated fats, to facilitate their flow. POWERSUPPLY.A full-wave bridge rectifier was used to and Sa. Four Type 866A/866 mercuryenergize solenoids S1,SZ, vapor tubes were employed in the network, and their electronic output was unfiltered. The wiring diagram and description of the components appear in.Figure 3.
Ohio
Valley
Spectrographic Society
Representatives of approximately fifteen industrial and educational laboratories in southwestern Ohio, meeting in Dayton, Ohio, have formed the Ohio Valley Spectrographic Society. The group is interested in promoting interest in and knowledge of spectrographic analysis. Meetings will be held every six w e e b in Cincinnati, Columbus, Dayton, or Middletown, Ohio. Information concerning the new organization may be obtained from Miss B. J. BeiseL Materials Laboratory, National Cash Register Co., Dayton 9, Ohio.
