Differential Manometer Research Articles

Respiratory carbon dioxide response curve computer

A special purpose analog computer which automatically plots the alveolar ventilation-alveolar PCo 2 response curve is described. The two inputs to the computer are a differential strain-gauge manometer output voltage which is proportional to the expiratory air flow in the rebreathing system and an infra-red carbon dioxide gas analyser output voltage corresponding to the carbon dioxide concentration in exhaled air. During each respiratory cycle, voltages representing the end-expiratory (alveolar) carbon dioxide and alveolar ventilation for the preceding cycle are fed to the X- and Y-axes respectively of an X-Y plotter. A typical response curve before and after 10 mg morphine is shown.

Radiocarbon Dating at the University of Washington. II

The radiocarbon dating equipment previously used (Dorn, Fairhall, Schell and Takashima, 1962) has been moved to a different location. During the resulting hiatus in our dating program we have constructed a new counter with a few novel features. It is similar in concept to the Houtermans-Oeschger counter (Houtermans and Oeschger, 1958), but two changes have been made in the design: (1) The inner counter, constructed of thin, metallized plastic foil of thickness 4.2 mg/cm2, is leak-tight relative to the outer counter. By means of two solenoid valves actuated by a simple differential mercury manometer the outer and inner counters can be filled separately with a pressure differential on the partition of less than 0.5 cm Hg. Thus all of the sample can be introduced into the inner counter while inert gas is fed into the outer counter. As the sample gas is not needed for anti-coincidence filling efficiency increases ca. 30%; (2) The metallic parts are made of commercially available high-purity nickel which is easier to procure than O.F.H.C. copper; nylon is used for the other parts. The outer counter appears to have a very low radioactivity, its α activity being 5 pulses/hr/100 cm2.

Measuring pulsating gas-flows

The above considerations show that until reliable data are available there is no point in including in the All-Union standard specification for measuring flows a recommendation for evaluating the error in measuring pulsating flows by means of the damping criterion and to classify the differential manometers combined with constricting devices among instruments with standardized errors.

Equipment for determining the frequency characteristics of differential manometer flowmeters

The above equipment and measurement technique make it possible to obtain dynamic characteristics of different recording differential and ordinary manometers, as well as of pressure transducers with a pneumatic output signal. For the latter purpose it is only necessary to use a second strain gauge, as described above, for recording the output signal and utilize the second channel of the TU-4M amplifier.

Experimental Study of the Flow Conditions and Pressure Drop of Steam-Water Mixtures at High Pressures in Heated and Unheated Tubes

The work described in the three parts of this paper was sponsored by the Water-Tube Boilermakers' Association and carried out in the Engineering Department of Cambridge University. In Part I are described the high-pressure experimental plant and its associated instrumentation. A description of the test circuit is followed by a detailed description of the construction and performance of the electrical low-frequency induction heaters specially developed to supply the power input to the test section. Auxiliary electrical resistance heaters are also described. The work required the development of special differential manometers and differential thermocouples suitable for the accurate measurement of small differences in pressure and temperature at high fluid pressures. Gamma-ray absorption equipment was used to make measurements of the apparent density of the two-phase mixture within a cross-section of the tube at the test-section outlet, from which estimates could be obtained of the relative or ‘slip’ velocity between the two phases. Part I of the paper ends with a description of the mode of operation of the plant and the range of variables covered during the tests. Part II deals with the analysis of the experimental results obtained from measurements of the absorption of gamma-rays in their passage through the two-phase mixture at outlet from the test section. The results of tests on the -in. bore pipe are examined first, although they were the last to be carried out. In these tests the tube cross-section was scanned by a narrow pencil of rays from a collimated beam, and scintillation-counter equipment was used to measure the intensity of the emergent radiation. Preliminary tests involving scans along a number of chords of the tube cross-section gave information on the density distribution of the fluid within the cross-section; this was different for the vertical and horizontal pipes. Data from these readings enabled the main series of tests, during which pressure-drop readings were also taken, to be carried out with a single scan along the tube centre-line only. From the readings taken during the latter tests the area dryness-fraction (void fraction) and slip velocity ratio were calculated and correlated as functions of the mass dryness-fraction. The paper then gives a brief presentation of the less satisfactory results obtained on the 1-in. bore pipe with full-area scanning by an uncollimated beam using an ionization chamber as detector. The foregoing correlations are finally used to calculate slip correction factors by means of which the acceleration and gravitational pressure-drops calculated according to homogeneous theory may be corrected for the effects of slip. The application of these factors to the analysis of the experimental pressure-drops is studied in Part III. Part III presents an analysis of the pressure-drop measurements made on the . bore pipes in both the horizontal and vertical positions, giving particular attention to comparisons between the experimental results and values predicted by homogeneous theory. These comparisons are made in terms of dimensionless pressure-drop coefficients which enable the respective contributions of friction, acceleration and gravitation to the total pressure drop to be readily displayed. Use is made of the correction curves derived in Part II to apply a correction for the effects of slip to the acceleration and gravitational pressure-drops predicted by homogeneous theory, and thence to compare the corrected predictions of pressure drop with the experimental values. In an analysis of the results for the horizontal pipes, the frictional pressure-drop under two-phase conditions is evaluated, for the heated pipes, by subtracting from the measured total pressure-drop an estimated acceleration pressure-drop allowing for the effects of slip. Correlation of the frictional pressure-drops in both the heated and unheated pipes enables these to be related to the corresponding homogeneous values through a suitable correction factor. The pipes were fortuitously of different roughness, and the relation of the effective two-phase friction factors to the respective single-phase factors is studied. In the vertical pipes, the gravitational contribution to the total pressure-drop being dominant, the experimental results are compared favourably with predictions in which the gravitational term is computed by correcting the homogeneous value for the effects of slip, while the frictional and acceleration terms are taken to be the same as the homogeneous values. Additional correction of the frictional term in the unheated pipes is seen to give a small improvement in accuracy of prediction. In a concluding section, values of the slip ratio are deduced from pressure-drop measurements on the vertical, unheated pipes, so carrying through the reverse procedure of Part II, and these values are compared with the values deduced from the gamma-ray measurements in Part II.

Defects in the differential manometers made by the ?Teplokontrol' ? Kazan' Plant

Defects in the differential manometers made by the ?Teplokontrol' ? Kazan' Plant

A bell differential manometer DKFM

A bell differential manometer DKFM

Studies on polyoxypropylene glycols. Part I. Vapor pressures and heats of mixing in the systems: Polyglycols–methanol

AbstractThermodynamic studies have been made on various fractions of polyoxypropylene glycols of molecular weights from 150 to 3350 in methanol. Vapor pressures of the solvent and the relative lowering of vapor pressure of the solvent by the polymer have been determined in a special differential manometer over the temperature range −30°C. to 28°C. Heats of mixing for the systems have been determined in an isothermal phase‐change calorimeter empolying diphenyl ether as the dilatometric fluid. The relative partial molar free energies are derived for the solvent and solute.

Bakeable bellows-type differential pressure manometer

Bakeable bellows-type differential pressure manometer

Consumption-measuring differential manometers with automatic correction for several gas parameters

Consumption-measuring differential manometers with automatic correction for several gas parameters

The calculation of the constant for differential manometers

The calculation of the constant for differential manometers

THE EFFECT OF CARBON MONOXIDE ON OXYGEN CONSUMPTION, GLUCOSE UTILIZATION, AND GROWTH IN MAMMALIAN CELLS IN VITRO

The effect of carbon monoxide on respiration, growth, and carbohydrate metabolism of Earle's L strain cells was investigated. The rate of gas uptake by suspensions of cells in a Warburg respirometer was the same from mixtures containing various proportions of CO/O2/N2or containing only O2/N2. Apparently carbon monoxide was not inhibiting oxygen consumption. In respirometers filled with carbon monoxide and oxygen in the ratio of 9:1, illumination caused the net gas uptake to rise 23% above that of the controls. This suggests that the rate of oxygen consumption in the dark was reduced as a consequence of an inhibition of a respiratory enzyme by carbon monoxide. In keeping with this suggestion, a spectroscopic examination revealed the presence in L cells of absorption bands corresponding to those of the cytochrome enzymes. Using differential manometers it was established for the first time that carbon monoxide is taken up by L cells in the dark. It is concluded that a fraction of the gas uptake which is represented by the consumption of oxygen associated with normal metabolism must be reduced in the presence of carbon monoxide. It is also concluded that L cells oxidize carbon monoxide to carbon dioxide. The rate of multiplication of cells was reduced by carbon monoxide while the rate of glucose breakdown and lactic acid production were markedly accelerated, suggesting that there was an inhibition of cytochrome oxidase. Low partial pressures of oxygen also reduced the rate of multiplication of L cells while increasing the rate of glucose disappearance and the rate of lactic acid production. The observations reported here thus emphasize the role of aerobic oxidations in the maintenance of the maximum rate of growth.

THE EFFECT OF CARBON MONOXIDE ON OXYGEN CONSUMPTION, GLUCOSE UTILIZATION, AND GROWTH IN MAMMALIAN CELLS IN VITRO

The effect of carbon monoxide on respiration, growth, and carbohydrate metabolism of Earle's L strain cells was investigated. The rate of gas uptake by suspensions of cells in a Warburg respirometer was the same from mixtures containing various proportions of CO/O2/N2or containing only O2/N2. Apparently carbon monoxide was not inhibiting oxygen consumption. In respirometers filled with carbon monoxide and oxygen in the ratio of 9:1, illumination caused the net gas uptake to rise 23% above that of the controls. This suggests that the rate of oxygen consumption in the dark was reduced as a consequence of an inhibition of a respiratory enzyme by carbon monoxide. In keeping with this suggestion, a spectroscopic examination revealed the presence in L cells of absorption bands corresponding to those of the cytochrome enzymes. Using differential manometers it was established for the first time that carbon monoxide is taken up by L cells in the dark. It is concluded that a fraction of the gas uptake which is represented by the consumption of oxygen associated with normal metabolism must be reduced in the presence of carbon monoxide. It is also concluded that L cells oxidize carbon monoxide to carbon dioxide. The rate of multiplication of cells was reduced by carbon monoxide while the rate of glucose breakdown and lactic acid production were markedly accelerated, suggesting that there was an inhibition of cytochrome oxidase. Low partial pressures of oxygen also reduced the rate of multiplication of L cells while increasing the rate of glucose disappearance and the rate of lactic acid production. The observations reported here thus emphasize the role of aerobic oxidations in the maintenance of the maximum rate of growth.

The effect of immune sera on the respiration of Trypanosoma brucei in vitro

1. Blood-stream forms of Trypanosoma brucei ‘O’ strain from infected rats were separated from the blood by differential centrifugation. After washing, the trypanosomes were suspended in modified Ringer-phosphate solution with 0·2m glucose, and normal or immune rabbit serum was added. The oxygen uptake of such trypanosome suspensions was measured at 37° C. for 2 hr. with differential manometers using microflasks of 5 ml. capacity.2. Immune sera that affected the motility of the trypanosomes also caused a decrease in oxygen uptake.3. Some trypanosomes appeared to be unaffected by the less active concentrations of immune sera, while other trypanosomes in the same suspension were clumped together or lysed.4. The most active serum inhibited oxygen uptake less at the highest concentration tested (1/4·5) than at lower concentrations (1/9 and 1/20).5. This technique was less sensitive than Soltys's method (1957) for demonstrating neutralizing antibodies in the same sera.

Solution properties of polyvinyl acetate

AbstractThe depression of the vapor pressure over solutions of fractionated polyvinyl acetate in benzene and ethanol was studied using a differential manometer. The Huggins' equation was obeyed within the concentration range used, i.e., up to 10% solute concentration. The semiempirical constant μ was evaluated for different fractions and was found to vary with the average molecular weight of the polymer. The heat and entropy of dilution were calculated for one fraction in benzene solution, and the results are discussed in terms of the existing theories of high polymer solutions.

A method of obtaining accurate relative pressures in the range 20 to 200 mm of mercury

A refined visual method of accurately setting a mercury surface to a tungsten reference point is described in detail The technique is applied in a differential manometer system to the establishment of a scale of relative pressures which is self-consistent to better than two parts in 100 000.

The oxygen uptake of Trypanosoma lewisi and Trypanosoma equiperdum, with especial reference to oxygen consumption in the presence of amino-acids.

1. Standard conditions are described for preparing suspensions of washedTrypanosoma lewisiandT. equiperdumin modified Ringer–phosphate solution.2. Oxygen consumption was measured with differential manometers, using microflasks containing 2–5 × 107trypanosomes in 0·9 ml. of reaction mixture. Measurements of oxygen uptake were carried out at 37° C.3.T. lewisirespired slowly in the absence of substrate for up to 2 hr. The trypanosomes suffered little damage when stored at 5° C. for 24 hr. without substrate. No oxygen uptake was observed withT. equiperdumin the absence of substrate. The trypanosomes were viable after 24 hr. at 5° C. with glucose or glycerol as substrate, but not in the absence of substrate.4. With glucose as substrate, the rate of oxygen consumption byT. lewisiincreased with the age of infection. This change was more marked with glutamine as substrate.5. With glucosamine as substrate, the oxygen uptake ofT. lewisiwas at a slightly lower rate than with glucose. The rate of oxygen uptake was still lower with Nal-glutamic acid, asparagine, aspartic acid, casein hydrolysate, yeast extract and Difco Bacto-peptone. Thirteen other amino-acids had no effect on the motility of the trypanosomes.6. With glycerol as substrate, the oxygen uptake ofT. equiperdumwas at a slightly lower rate than with glucose. The rate of oxygen uptake was very low with yeast extract, casein hydrolysate and Difco Bacto-peptone. No oxygen uptake or motility was recorded with glutamine, Nal-glutamic acid, glucosamine, asparagine, aspartic acid,dl-alanine, or Na acetate. Thirteen other amino-acids had no effect on the motility of the trypanosomes.7. Ammonia was liberated from glutamine by adult and reproductive phaseT. lewisi.

The effect of some metabolic inhibitors on the oxygen uptake of Trypanosoma lewisi and Trypanosoma equiperdium.

1. The oxygen uptake ofTrypanosoma lewisiandT. equiperdumwas measured with differential manometers using microflasks of 5 ml. capacity. Each flask contained 2–5 × 107trypanosomes.2. The oxygen uptake of trypanosomes in heparinized infected blood was compared with that of washed trypanosomes suspended in Ringer–phosphate–glucose solution with or without added serum or blood. WithT. lewisi, the oxygen uptake began at a higher rate in the presence of blood or serum than with Ringer–phosphate–glucose solution. WithT. equiperdum, the oxygen uptake in the presence of blood or serum began at almost the same rate as with Ringer–phosphate–glucose solution, but the rate of oxygen uptake decreased more rapidly in the absence of blood or serum than when it was present.3. High concentrations of iodoacetic acid (e.g. 3·3 × 10−2m) caused an increase in oxygen uptake when tipped into heparinized normal rat blood. Similar concentrations caused an inhibition of oxygen uptake when 2·0 × 10−4mmethylene blue was also present or when the blood had been treated with sodium nitrite to convert haemoglobin into methaemoglobin.4. Iodoacetic acid caused little inhibition of oxygen uptake whenT. lewisiwas suspended in Ringer–phosphate solution containing glutamine or glutamine plus glucose, or when heparinized infected blood was tested. Inhibition was greatest when the substrate was glucose, while glucosamine, glycerol, or glucose plus serum gave intermediate results.5. Iodoacetic acid caused least inhibition of oxygen uptake whenT. equiperdumwas suspended in Ringer–phosphate solution containing glycerol, or when heparinized infected blood was tested. Inhibition was greatest when the substrate was glucose, and was slightly less marked when the substrate was glucose plus serum or glucose plus glycerol.6. Neoarsphenamine inhibited the oxygen uptake ofT. lewisito a similar extent whether glucose or glutamine was present.7. Neoarsphenamine and reduced stovarsol thioglycollate inhibited the oxygen uptake ofT. equiperdumslightly less when the substrate was glycerol than when it was glucose. Sodium arsenite was as active as reduced stovarsol thioglycollate when the substrate was glucose, but 10−4msodium arsenite had little effect when the substrate was glycerol.

The Leon tube: An instrument for measuring flow speeds in water

A description is given of the construction and performance characteristics of an instrument which is capable of measuring flow speeds in water a point over a range of 1 to 14 ft/s. The accuracy at 1 ft/s is approximately 1½% and improves rapidly with increasing speed. The Leon tube is of robust and compact construction and is, in effect, a combination of a differential pressure tube and a differential liquid manometer. The pressure factor of the tube, which is a function of Reynolds number, is most readily determined in a wind tunnel. The instrument has proved to be particularly suitable for the performance of velocity traverses in open channels.

Pulsation Errors in Manometer Gages

Abstract It is known that manometer gages of conventional design are subject to errors when the gas-pressure differential is pulsating. In this paper, various factors contributing to the production of such errors are analyzed and the requirements for their elimination established. A differential manometer capable of indicating the true time-mean of a pulsating head is described.