Mechanical Compressor Research Articles

Gas transfer device utilizing a mechanical piston compressor

Un dispositif totalement mecanique de transfert d'un echantillon de gaz d'un recipient, a une pression donnee vers un recipient de volume plus petit, a une pression plus elevee, en vue de l'analyse quantitative, est decrit

Relationship of blood pressure and flow during CPR to chest compression amplitude: Evidence for an effective compression threshold

This study was conducted to investigate the importance of the depth of chest compression in producing effective cardiopulmonary resuscitation (CPR) in animals, as indicated by cardiac output and mean arterial blood pressure. Cardiac output was measured by a modified indicator dilution technique in 8 anesthetized dogs, 6 to 12 kg body weight, during repeated 2-minute episodes of electrically induced ventricular fibrillation and CPR provided by a mechanical chest compressor and ventilator (Thumper). Chest compression exceeding a threshold value (xo) between 1.5 and 3.0 cm was required in each animal to produce measurable cardiac output. In particular, cardiac output (CO) was linearly related to chest compression depth (x) by an expression of the form CO = a(x-xo) for x greater than xo. The mean value of xo was 2.3 cm. A similar threshold for measurable blood pressure was observed in 7 of the 8 dogs, with a mean value of 1.8 cm. For chest compression of 2.5 cm or greater, relatively modest increases in chest compression depth caused relatively large changes in cardiac output.

MAST augmentation of external cardiac compression: Role of changing intrapleural pressure

Ventricular fibrillation was induced in nine dogs weighing 18 to 22 kg. CPR was performed with a mechanical chest compressor. Mean carotid flow during CPR was 7.9 +/- 1.5 ml/min. After MAST inflation to 100 mm Hg, the flow increased to 15.7 +/- 3.7 ml/min. Intrathoracic aortic systolic pressure was also significantly increased from 65 +/- 7 to 73 +/- 8 mm Hg. When the thorax was vented with chest tubes bilaterally, no change in carotid flow or arterial pressure was noted on closing or opening the chest tubes. One liver laceration and two gallbladder contusions were noted at autopsy. MAST inflation apparently augments carotid flow an systolic pressure. Variations in intrapleural pressure do not seem to have a significant influence on CPR.

Cardiac output during cardiopulmonary resuscitation at various compression rates and durations.

Cardiac output during cardiopulmonary resuscitation (CPR) was measured by a modified indicator-dilution technique in 20 anesthetized dogs (6-12 kg), during repeated 1- to 2-min episodes of electrically induced ventricular fibrillation, by a mechanical chest compressor and ventilator. With compression rates from 20 to 140/min and compression durations (duty cycles) from 10 to 90% of cycle time, cardiac output (CO) was predicted by the equation: CO = CR . SVmax . [DC/(k1 . CR + DC)] . [(1 -- DC)/k2 . CR + 1 - DC)], where CR is compression rate, DC is duty cycle, SVmax (19 ml) is the effective capacity of the pumping chamber, and k1 (0.00207 min) and k2 (0.00707 min) are ejection and filling constants. This expression predicts maximal CO for DC = 0.40 and cR = 126/min and 90-100% of maximal CO for 0.3 less than DC less than 0.5 and 70 less than CR less than 150/min. Such mathematical analysis may prove useful in the optimization of CPR.

INfluence of interposed ventilation pressure upon artificial cardiac output during cardiopulmonary resuscitation in dogs.

This study was conducted to determine the effects of high pressure interposed ventilations during cardiopulmonary resuscitation (CPR). Cardiac output was measured by a modified indicator dilution technique in eight anesthetized, intubated mongrel dogs. Positive pressure ventilations (12/min, 80% O2) were interposed after every five chest compressions (performed at 62/min) by a mechanical chest compressor (Thumper). On repeated trials in the same animal, ventilation pressures from 10--50 cm of H2O were tested in randomized sequence, while the technique of chest compression was held constant. Arterial blood gases immediately after resuscitation were monitored. Increasing ventilation pressure had surprisingly little effect on cardiac output curing CPR, although blood gases were profoundly altered. For ventilation pressures of 10, 20, 30, 40, and 50 cm of H2O, producing mean tidal volumes 23, 38, 61, 83, and 94 ml/kg; cardiac output remained nearly constant, averaging 21, 25, 23, 26, and 24 ml/min . kg. Corresponding mean postresuscitation pH was 7.24, 7.41, 7.51, 7.56, and 7.53; PCO2 was 41, 26, 18, 16, and 15 torr. The postresuscitation arterial oxygen tension was greater than 100 torr at all ventilation pressures except 10 cm of H2O. Interposed ventilations of pressure and volume more than adequate to prevent acidosis during CPR did not impair artificial cardiac output. If anything, cardiac output was slightly improved by more forceful ventilation.

Influence of adrenergic drugs upon vital organ perfusion during CPR.

To determine whether adrenergic drugs administered during CPR alter the distribution of artificial cardiac output, the authors measured regional blood flow and cardiac output using radioactive microspheres in 12 dogs. Ventricular fibrillation was induced electrically and CPR was immediately begun with a mechanical chest compressor and ventilator (Thumper) at 60 compressions/min, with a ventilation: compression ratio of 1:5, a compression duration of 0.5 sec, and a ventilation pressure of 20 cm H2O. Compression force was sufficient to develop 40--50 mm Hg peak intraesophageal pressure. After 30 sec of CPR, either 0.9% saline vehicle or 50 micrograms/kg of epinephrine, phenylephrine, or isoproterenol was administered through a central venous catheter. One min later, microspheres were injected into the left ventricle. After 250 sec of CPR, the ventricles were defibrillated electrically. Between each drug injection, 20-min recovery periods were interposed. Each dog received all three drugs and saline according to a predetermined sequence. After saline, epinephrine, phenylephrine, and isoproterenol treatment, respective, cardiac output averaged 392, 319, 255, and 475 ml/min; brain blood flow averaged 37, 54, 29, and 28 ml/min; coronary blood flow averaged 25, 79, 26, and 15 ml/min; and kidney blood flow averaged 44, 4, 16, and 29 ml/min. Epinephrine improved blood flow to the brain, probably because of its alpha-adrenergic activity. Epinephrine improved blood flow to the heart during CPR much more than the other agents, probably because of its combined alpha- and beta-adrenergic activity. This effect may explain its superiority in restoring circulation after prolonged arrest and resuscitation. Isoproterenol should not be used in CPR because it shunts blood away from vital organs.

Computer Aided Design Studies of a Multiple Cylinder Refrigeration Compressor

A multi-cylinder refrigerant compressor was analytically modeled and simulated on a digital computer. The modeling includes the kinematics of the mechanical compressor, the thermodynamic processes in the cylinders and the flow process of the refrigerant gas in and out of the cylinders. In addition the modeling includes the valve dynamics in controlling the gas flow, the thermodynamic processes in the common suction and discharge plenums and the interaction of the cylinder processes through the common plenums. The remainder of the refrigeration system was treated as pressure-temperature drop. The analytical model was compared to experimental data in terms of cylinder pressures, suction-discharge plenum pressures and temperatures, valve motions and the average mass flow rate of the refrigerant gas. The correlation between the comparison variable was quite good with some error in the prediction of suction valve closing time. The analytical model was used to predict the effect of increased compressor speed on the performance of the compressor. The speed was increased from 500 rpm to 2700 rpm with a decrease in volumetric efficiency from 87 percent to 60 percent, an increase in mass flow rate from 0.0378 kg/s to 0.151 kg/s. Valve impact speeds were also calculated to predict degradation in valve life.

The zero mechanical work thermal compressor or pump in the high speed rotating frame

The zero mechanical work thermal compressor or pump in the high speed rotating frame

A superconducting magnetic flux compressor

The design and operation of a mechanical superconducting flux compressor is described. The compressor is constructed of movable interleaved plates, rather like a variable capacitor. Increasing the overlap of the two sets of plates decreases the size of a hole in which magnetic flux is trapped, thus increasing the flux density.

A mechanical flux compressor using superconducting sintered Nb 3Sn tubes

The magnetic and electrical properties of superconductors were a challenge for many inventors and designers to use superconducting materials in the construction of fully superconducting voltage and current sources commonly called fluxpumps. In the past twenty years a large variety of mechanically or electrically driven devices have been proposed and successfully operated.In this review the basic principle of operation of each class of devices is shown and specific material problems and limitations are reported. The review will be published in two parts.Part 1 deals with mechanical devices such as flux compressors and dynamos. Although those devices must have been of great importance for technical application, their construction and operation offered great experience with regard to the properties of superconducting materials, their joint techniques switching and mechanical and magnetic stability under ac and dc conditions.In this part also a start is made with the more promising class of electrically driven rectifier fluxpumps. With these rectifiers, current levels over 10 kA can be obtained with high efficiency.In part 2 a theoretical comparison between dynamos and transformer rectifiers will conclude the review.

Low Temperature Force Generating Apparatus Using Sylphon Bellows

An apparatus is described in which a Sylphon bellows is used to generate pressures to 3400 atm or uniaxial forces to 1150 kg in the liquid helium temperature range without the use of mechanical compressors. Correction factors, operating procedures, and practical limitations of the design are discussed. The shift in transition temperature of indium is given as a test of the overall behavior of the apparatus.

Flux trapping and compression in superconducting niobium - tin tubes

Niobium-tin compacts have been produced by pressing and sintering the powdered elements. Tube magnetization experiments on the material at 4.2°K in fields of up to 54 kOe have yielded results that are consistent with the relation Jc = αc/(H + B0), where Jc is the critical current density in a local magnetic field H and αc and B0 are constants. The highest critical current density to date has been achieved by pressing at 30 ton in-2 and sintering at 975°C for 3 hours; the values of αc and B0 for niobium-tin prepared in this way are 4 × 106 kOe A cm-2 and 4 kOe respectively. The material is notable in that it seldom exhibits flux jumps; it is thought that this feature of its behaviour is due to the presence of liquid helium in the interconnected pores. The absence of flux jumps indicates that the material can be used in the construction of mechanical flux compressors and the design of a flux compressor, which can yield 50 kOe in a working space of 1 cm diameter, is discussed. Preliminary experiments on flux compression up to a field of 23 kOe have given results in accordance with the theoretical predictions.

Application of motors to household refrigeration compressors

HOUSEHOLD refrigeration has come a long way since the days when the ice came from a commercial ice-making plant, lake or river and was placed in an ice box. The first mechanical compressor consisted of a pump, belt driven by an electric motor. There were shaft seals in the pump to prevent the refrigerant and oil from escaping. The belt and shaft seals were troublesome. The manufacturers did the best they could to make as good a box, and the mechanism as quiet, efficient, and free of vibration as was possible at that time. However, with all its shortcomings, the housewife welcomed this type of refrigeration in preference to the old ice box.

Improved guns for the delivery of liquid D.D.T. spray and powder by mechanical compressors

On the basis of experience in using D.D.T. as an insecticide in both liquid and powder forms, suggestions are made for improved spray and dust guns.My thanks are to S./Sgt. Toop, workshop foreman, and Pte Carter, tinsmith, of my old hygiene section, for the months of experiment, trial and error involved in producing these apparently simple innovations. Also to Brigadier H. B. F. Dixon, D.D.M.S. West Africa Command, for permission to forward this article for publication.

The Control of Air-Borne Bacteria and Fungus Spores By Means Of Aerosols

IN a previous communication we (Pulvertaft, Lemon & Walker, 1939), gave an account of a method of sterilizing air by means of finely atomized antiseptic solutions, founded on the principles outlined by Trillat (1938). His claims were fully confirmed.The mists used in this method may be produced by a number of different appliances, and in the experiments here described were produced by the “Phantomyst” (Andre Components, Ltd.). The essential appliances are:(1) a mechanical compressor, electrically driven, and (2) an atomizer, usually of scent-spray type, provided with (3) a baffling system which returns to the reservoir droplets above a certain size, thus avoiding much wastage.