U-tube Manometer Research Articles

Analysis of the positive expiratory pressure valves of coupled oronasal mask

Positive expiratory pressure (PEP) is a technique used in respiratory physiotherapy to treat diseases related to the respiratory system through spontaneous breathing. This equipment consists of an oronasal mask coupled to a T connector with a unidirectional valve. Studies that evaluate whether the pressure level in the one-way valve corresponds to the actual pressure level provided are scarce in the scientific literature. In order to investigate the failures, bench tests were carried out on the spring-loaded valves, using a U-tube manometer. This pressure was exerted on the valve using a syringe that generated air flow inside the U-tube, allowing analysis numerical value of the measured pressure and the specified values of the valve, thus verifying the disparity of these measured values in relation to the PEP values operated by valves (0 to 20 cmH2O) from the three manufacturers under study. PEPs generated by spring-loaded valves from all three manufacturers were higher than pressures in the range of 2.5 to 20 cmH2O, with significant differences between manufacturers. This bench study showed inaccurate operation of all spring-loaded PEP valves of the three manufactures. The results obtained and the performance of the valves require a reevaluation of manufacturing procedures to preserve product quality and efficacy in clinical application.

An Analysis Of Flow Capacity Variation and Distance Between Louvered Strip Constant Angle 25o Of Heat Transfer and Pressure Decrease On The Heat Exchanger

This study aims to determine the effect of variations in flow rate and the louvered strip inclination angle on heat transfer in a double-pipe heat exchanger and the impact of variations in flow rate and inclination angle of the louvered strip on the inner tube pressure drop in a double-pipe heat exchanger. Three pieces of louvered strips at 50 mm, 70 mm, 90 mm are inserted into the inner tube of the heat exchanger with a constant tilt angle of 25°. Cold and hot water are used at a constant value where the cold-water flow rate is 600 liters/hour and V = 900 liters/hour, while the hot water flow rate is 1200 liters/hour. The inlet and outlet temperatures of both hot and cold water are measured, and the heat transfer characteristics of the heat exchanger are calculated as a result of the pressure drop that occurs in the inner tube due to the difference in height on the U-tube manometer used.

Disposable Airway Pressure Manometers for Endotracheal Tube Cuff Inflation.

This study aimed to assess the performance, accuracy, precision and repeatability of two single-use airway pressure manometers as a cost-effective alternative for inflation of endotracheal tubes with high-volume, low-pressure cuffs. The manometers were tested in a bench top model against a U-tube manometer. Eighteen units of each device were tested. Three consecutive measurements were performed at pressures of 20, 25 and 30 cmH2O each. The mean ± SD of the recorded pressures and maximum deviation from the target pressures were calculated for each device and each target pressure. For device A, the mean ± SD pressures were 19.6 ± 0.7, 23.6 ± 0.8 and 28.3 ± 0.8 cmH2O; for device B, the mean ± SD pressures were 19.3 ± 0.6, 24.3 ± 0.9 and 29.2 ± 0.67 cmH2O for target pressures of 20, 25 and 30 cmH2O, respectively. The bias for device A was -0.4, -1.4, and -1.7 cmH2O and for device B, -0.7, -0.7, and -0.8 cmH2O for target pressures of 20, 25, and 30 cmH2O, respectively. Both devices showed results comparable to those reported for commercial cuff manometers. They represent inexpensive tools that provide clinically sufficient accuracy, precision and repeatability for ETT cuff inflation between pressures of 20 and 30 cmH2O.

Effect of Conical Strip Inserts and ZrO2/DI-Water Nanofluid on Heat Transfer Augmentation: An Experimental Study

There is a significant enhancement of the heat transfer rate with the usage of nanofluid. This article describes a study of the combination of using nanofluid with inserts, which has proved itself in attaining higher benefits in a heat exchanger, such as the radiator in automobiles, industries, etc. Nanofluids are emerging as alternative fluids for heat transfer applications due to enhanced thermal properties. In this paper, the thermal hydraulic performance of ZrO2, awater-based nanofluid with various volume concentrations of 0.1%, 0.25%, and 0.5%, and staggered conical strip inserts with three different twist ratios of 2.5, 3.5, and 4.5 in forward and backward flow patterns were experimentally tested under a fully developed laminar flow regime of 0–50 lphthrough a horizontal test pipe section with a length of 1 m with a constant wall heat flux of 280 W as the input boundary condition. The temperatures at equidistant position and across the test section were measured using K-type thermocouples. The pressure drop across the test section was measured using a U-tube manometer. The observed results showed that the use of staggered conical strip inserts improved the heat transfer rates up to that of 130.5%, 102.7%, and 64.52% in the forward arrangement, and similarly 145.03%, 116.57%, and 80.92% in the backward arrangement with the twist ratios of 2.5, 3.5, and 4.5 at the 0.5% volume concentration of ZrO2 nanofluid. It was also seen that the improvement in heat transfer was comparatively lower for the other two volume concentrations considered in this study. The twist ratio generates more swirl flow, disrupting the thermal hydraulic boundary layer. Nanofluids with a higher volume concentration lead to higher heat transfer due to higher effective thermal conductivity of the prepared nanofluid. The thermal performance factor (TPF) with conical strip inserts at all volume concentrations of nanofluids was perceived as greater than 1. A sizable thermal performance ratio of 1.62 was obtained for the backward-arranged conical strip insert with 2.5 as the twist ratio and a volume concentration of 0.5% ZrO2/deionized water nanofluid. Correlations were developed for the Nusselt number and friction factor based on the obtained experimental data with the help of regression analysis.

Air Flow Analysis and Effect of Angle on Rotation Vane Blade Trough 90° Pipe Bend

The usual problem occurs when fluid flow pass through elbow or 90° pipe bend is that secondary flow will exist which then lead to high pressure drop. The high pressure drop happen will affect the elbow which is erosion will appear. To overcome this problem, a rotation vane blade with different angles are installed at the pipe. The rotation vane blade will reduce the pressure drop that happened. In this paper, analysis of air flow through 90 pipe bend and the effect of angle rotation vane blade toward it is investigated. The process of the investigation is made through experiment. The inlet velocity used in this experiment are 1.20, 1.30, 1.40, 1.45 and 1.50 m/s. Furthermore, all the inlet velocity produced turbulence flow. Then, rotation vane blade of angle 18° and 33° are installed between the pipes by turn before the 90° pipe bend. U-tube manometer are attached at two places which is Section A-A (before elbow) and Section B-B (after elbow). From this experiment, elevation heights that measured by u-tube manometer of the two sections which are located before and after the 90 pipe bend are recorded. Next, the elevation heights will be used in the Bernoulli equation in order to calculate the velocity distribution at all sections, pressure distribution at all sections and pressure drop between both sections. The result of this experiment show that the rotation vane blade produced slower velocity at section B-B and higher pressure at section B-B. Pressure drop between both sections A-A and B-B is lower when using larger angle of rotation vane blade (33°).

Blood pressure measurement: lessons learned from our ancestors.

The profound observations of William Harvey (1578-1657), in blood circulation and the progress of physical science laid the foundation for the development of the Iatrophysical School that contributed to the evolution of clinical sphygmomanometry. The pioneer work of Reverend Stephen Hales (1677-1761) demonstrated the dynamics of the vascular system. One century later the French physician Jean-Léonard-Marie Poiseuille (1797-1867) invented a U-tube mercury manometer and in 1860 the physiologist Etienne- Jules Marey (1830-1904) devised the first portable sphygmograph for recording the pulse wave. The non-invasive techniques of blood pressure measurement were completed by Scipione Riva-Rocci (1896-1937) sphygmomanometer and the description of "Korotkov sounds" by the Russian surgeon Nikolai- Sergeyevich Korotkov (1874-1920).

Comparison of Pleural Pressure Measuring Instruments

The objective of this study was to compare the accuracy of a handheld digital manometer (DM) and U-tube (UT) manometer with an electronic transducer (ET) manometer during thoracentesis. Thirty-three consecutive patients undergoing thoracentesis were enrolled in the study. Pleural pressure (Ppl) measurements were made using a handheld DM (Compass; Mirador Biomedical), a UT water manometer, and an ET (reference instrument). End-expiratory Ppl was recorded after catheter insertion, after each aspiration of 240 mL, and prior to catheter removal. Volume of fluid removed, symptoms during thoracentesis, pleural elastance, and pleural fluid chemistry were also evaluated. A total of 594 Ppl measurements were made in 30 patients during their thoracenteses. There was a strong linear correlation coefficient between elastance for the DM and ET (r = 0.9582, P < .001). Correlation was poor between the UT and ET (r = 0.0448, P = .84). Among the 15 patients who developed cough, recorded ET pressures ranged from -9 to +9 cm H2O at the time of symptom development, with a mean (SD) of -2.93 (4.89) cm H2O. ET and DM measurements among those patients with cough had a low correlation between these measurements (R2 = 0.104, P = .24). Nine patients developed chest discomfort and had ET pressures that ranged from -26 to +6 cm H2O, with a mean (SD) of -7.89 (9.97) cm H2O. The handheld DM provided a valid and easy-to-use method to measure Ppl during thoracentesis. Future studies are needed to investigate its usefulness in predicting clinically meaningful outcomes.

A simple and inexpensive method for muddy shore profiling

There are several well-established methods for obtaining beach profiles, and more accurate and precise high-tech methods are emerging. Traditional low-cost methods requiring minimal user skill or training are still popular among professionals, scientists, and coastal zone management practitioners. Simple methods are being developed with a primary focus on sand and gravel beaches. This paper describes a simple, low-cost, manual field method for measuring profiles of beaches, which is particularly suitable for muddy shores. The equipment is a type of flexible U-tube manometer that uses liquid columns in vertical tubes to measure differences in elevation; the supporting frame is constructed from wooden poles with base disks, which hold measuring scales and a PVC tube. The structure was trialed on a mudflat characterized by a 20–40-cm-thick surface layer of silt and clay, located at the Kutubdia Island, Bangladesh. The study results are discussed with notes on the method’s applicability, advantages and limitations, and several optional modifications for different scenarios for routine profiling of muddy shores. The equipment can be used by one person or two people, and the accuracy of the method is comparable to those in other methods. The equipment can also be used on sandy or gravel beaches.

Experimental Study on the Flow Regimes and Pressure Gradients of Air-Oil-Water Three-Phase Flow in Horizontal Pipes

An experimental investigation has been carried out to study the flow regimes and pressure gradients of air-oil-water three-phase flows in 2.25 ID horizontal pipe at different flow conditions. The effects of water cuts, liquid and gas velocities on flow patterns and pressure gradients have been studied. The experiments have been conducted at 20°C using low viscosity Safrasol D80 oil, tap water and air. Superficial water and oil velocities were varied from 0.3 m/s to 3 m/s and air velocity varied from 0.29 m/s to 52.5 m/s to cover wide range of flow patterns. The experiments were performed for 10% to 90% water cuts. The flow patterns were observed and recorded using high speed video camera while the pressure drops were measured using pressure transducers and U-tube manometers. The flow patterns show strong dependence on water fraction, gas velocities, and liquid velocities. The observed flow patterns are stratified (smooth and wavy), elongated bubble, slug, dispersed bubble, and annular flow patterns. The pressure gradients have been found to increase with the increase in gas flow rates. Also, for a given superficial gas velocity, the pressure gradients increased with the increase in the superficial liquid velocity. The pressure gradient first increases and then decreases with increasing water cut. In general, phase inversion was observed with increase in the water cut. The experimental results have been compared with the existing unified Model and a good agreement has been noticed.

CFD simulation and experimental measurement of gas holdup and liquid interstitial velocity in internal loop airlift reactor

This paper documents experiments and CFD simulations of the hydrodynamics of our two-phase (water, air) laboratory internal loop airlift reactor (40 l). The experiments and simulations were aimed at obtaining global flow characteristics (gas holdup and liquid interstitial velocity in the riser and in the downcomer) in our particular airlift configurations. The experiments and simulations were done for three different riser tubes with variable length and diameter. Gas (air) superficial velocities in riser were in range from 1 to 7.5 cm/s. Up to three circulation regimes were experimentally observed (no bubbles in downcomer, bubbles in downcomer but not circulating, and finally the circulating regime). The primary goal was to test our CFD simulation setup using only standard closures for interphase forces and turbulence, and assuming constant bubble size is able to capture global characteristics of the flow for our experimental airlift configurations for the three circulation regimes, and if the simulation setup could be later used for obtaining the global characteristic for modified geometries of our original airlift design or for different fluids. The CFD simulations were done in commercial code Fluent 6.3 using algebraic slip mixture multiphase model. The secondary goal was to test the sensitivity of the simulation results to different closures for the drag coefficient and the resulting bubble slip velocity and also for the turbulence. In addition to the simulations done in Fluent, simulation results using different code (CFX 12.1) and different model (full Euler–Euler) are also presented in this paper. The experimental measurements of liquid interstitial velocity in the riser and in the downcomer were done by evaluating the response to the injection of a sulphuric acid solution measured with pH probes. The gas holdup in the riser and downcomer was measured with the U-tube manometer. The results showed that the simulation setup works quite well when there are no bubbles present in the downcomer, and that the sensitivity to the drag closure is rather low in this case. The agreement was getting worse with the increase of gas holdup in the downcomer. The use of different multiphase model in the different code (CFX) gave almost the same results as the Fluent simulations.

Investigating pressure drop across wire mesh mist eliminators in bubble column

Effects of design parameters on pressure drop across the wire mesh mist eliminators were experimentally investigated in 15cm bubble column. The pressure drop across the demister pad was evaluated as a function of wide ranges of operating and design parameters. These parameters include: specific surface area (236–868m2/m3), void fraction (97–99%), wire diameter (0.14–0.28mm), packing density (130–240kg/m3), and superficial gas velocity (0.109–0.118m/s). All demisters were 15cm in diameter with 10cm pad thickness, made from 316L stainless steel layered type. Experiments were carried out using air–water system at ambient temperature and atmospheric pressure. The measurements of the pressure drop were done using a U-tube manometer device. The pressure drop across the demister pad is a combination of dry and wet pressure drops. In this work, the experimental investigations showed that the dry pressure drop is nil. The wet pressure drop was found to increase with increasing the demister specific surface area, packing density, and superficial gas velocity. In contrast, it was found to increase with decreasing the demister void fraction and wire diameter. The pressure drop is correlated empirically as a function of the design parameters. A good agreement was obtained between the measured values and the correlation predictions with ±15% accuracy.

Dynamic response of the U-tube liquid manometer with equal diameter columns

The paper presents numerical solving methods using MATLAB programming language of the governing equation of the liquid oscillations in a U-tube liquid manometer with equal diameter columns. Assuming some numerical values for geometrical and functional parameters of this pressure measurement system, the dynamic behavior of the oscillating system will be analyzed using four MATLAB based computational methods: the method of the default MATLAB procedures, the Simulink method, the Simscape method and the method of the Control System Toolbox procedures. According to all these methods, in almost all the cases analyzed, the dynamic behavior of the U-tube liquid manometer with equal diameter columns corresponds to an under-damped dynamic system. The influence of some important constructive and functional parameters (the columns diameter, the manometer liquid, the capillarity action and the connection tube between the reservoir and the manometer) has been investigated. Improving the dynamic response (decreasing the overshoot and the settling time, increasing the phase and delay margins) can be achieved by increasing the connection tube length, by decreasing the columns diameter and by using a high density liquid manometer.

A simple subatmospheric pressure device to drive reagents through microchannels for solution-phase synthesis in a parallel fashion

A simple but effective subatmospheric pressure device has been developed to drive reagents through microfluidic channels for solution-phase parallel synthesis. Y-shaped microfluidic glass chips with different channel lengths were fabricated using a photolithographic and wet chemical etching procedure. The subatmospheric pressure device, composed of a microvacuum pump, a buffer vessel and a vacuum gauge with two electric switches, can automatically adjust the applied vacuum range in the buffer vessel as required. With the subatmospheric pressure as the driving force, the fluid flow in parallel channels can be precisely controlled, respectively, by the needle valves and monitored by a water filled U-tube manometer. The system was evaluated with Suzuki coupling reaction in a parallel fashion as a demonstration. Experimental results confirmed that the developed system is superior for parallel synthesis parameter evaluation.

Pengujian Kinerja Pompa Sentrifugal Menggunakan Kontrol Inventer

An alternative method for obtaining data on pump discharge and head in order enable to determine pump characteristics has been investigated and formulated. Three types of centrifugal pump, the snails house, diffuser and turbine, have been selected. According to their respective manufacturers, the heads of these pumps are 16 m, 11 m and 9 m, respectively; their respective debits are 105 m3/h, 105 m 3/h and 150 m3/h; and their respective efficiencies are 95 %, 70 % and 95 %. Two testing parameters, shaft rotation and ball valve opening portion have been considered. Five different rotations, 1500 rpm, 1750 rpm, 2000 rpm, 2500 rpm and 2800 rpm, and seven different ball valve opening portions, 0 %, 25 %, 30 % 45 %. 60 %, 75 % and 100 %, have been considered. The main units of the alternative methods for measuring pump discharge and head are an electric motor, an inventer, a U-tube manometer and an orifice. The result shows that the heads the pumps are 15,4 m,11,45 m and 9,7 m, respectively, the debits of the pumps are 103 m3/h, 108 m 3/h and 171 m3/h, and efficiency are 98 %, 69,5 % and 97,5 %, respectively. Controlled inventer method can be used as one of the alternative pump performance test.

Pressure drop in liquid–solid circulating fluidized beds

AbstractAn experiment was conducted to obtain data for pressure drop in risers of liquid–solid circulating fluidized beds, where two different risers (24 mm and 36 mm in diameter) were used. Tested particles were of glass and ceramics, and their diameter ranged from 2.10 to 4.95 mm. Water under ambient conditions was used as the fluidizing liquid. Pressure drop in the risers was measured using a reversed U‐tube manometer. Based on the experimental data, a calculation method was derived for predicting the pressure drop in the riser, which could reproduce almost all the data with an accuracy of ±20%. Furthermore, the effect of independent parameters was investigated on the pressure drop component ratios consisting of the total pressure drop. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20241

Bend pressure drop experiments compared with Fluent

In the present study, experimental data for bend pressure drop were collected from a pilot plant test loop with a pipe diameter of 53 mm. The experiments were performed at three different efflux volumetric concentrations (0%, 3·94% and 8·82%) of 448·5μm silica sand particles and for each concentration the flow velocity was varied from 1·78 to 3·56 m/s. Pressure drops were measured using a multi-tube inverted U-tube manometer assembly, with separation chambers to prevent blockage of the connecting tubes. It was observed that pressure drop along the pipe bend increases with flow velocity and particle concentration. The experimental data for bend pressure drop collected in the present study have been compared with threedimensional computational fluid dynamics (CFD) modelling by running the commercial CFD code Fluent, and show good agreement (within a percentage deviation of ±10%). Modelling results indicate that the velocity and concentration distribution of solids become more uniform downstream, and the pressure at the outer wall is greater than that at the inner wall in the bend.

Why do we measure blood pressure in millimeters of mercury? [Retrospectroscope

The answer to the question in the title is not because the first person to make the measurement used a mercury manometer. In 1733, Rev. Stephen Hales was the first to measure blood pressure directly in an unanesthetized horse. It is interesting to note that Hales had used the U-tube manometer to measure the pressure of sap in plants. Meanwhile, Poiseuille successfully applied to blood flow in capillaries and veins, to air flow in lung alveoli, and to the flow through a drinking straw or a hypodermic needle.

Pressure Drop in Liquid-Solid Circulating Fluidized Beds

An experiment was conducted to obtain data for pressure drop in risers of liquid–solid circulating fluidized beds, where two different risers (24 mm and 36 mm in diameter) were used. Tested particles were of glass and ceramics, and their diameter ranged from 2.10 to 4.95 mm. Water under ambient conditions was used as the fluidizing liquid. Pressure drop in the risers was measured using a reversed U-tube manometer. Based on the experimental data, a calculation method was derived for predicting the pressure drop in the riser, which could reproduce almost all the data with an accuracy of ±20%. Furthermore, the effect of independent parameters was investigated on the pressure drop component ratios consisting of the total pressure drop. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20241

Vertical two-phase flow regimes and pressure gradients: Effect of viscosity

The effect of liquid viscosity on the flow regimes and the corresponding pressure gradients along the vertical two-phase flow was investigated. Experiment was carried out in a vertical transparent tube of 0.019 m in diameter and 3 m in length and the pressure gradients were measured by a U-tube manometer. Water and a 50 vol.% glycerol solution were used as the working fluids whose kinematic viscosities were 0.85 × 10 −6 and 4.0 × 10 −6 m 2/s, respectively. In our air–liquid annular two-phase flow, the liquid film of various thicknesses flowed adjacent to the wall and the gas phase flowed at the center of the tube. The superficial air velocity, j air, was varied between 0.0021 and 58.7 m/s and the superficial liquid velocity, j liquid, was varied between 0 and 0.1053 m/s. In the bubble, the slug and the slug–churn flow regimes, the pressure gradients decreased with increasing Reynolds number. But in the annular and the mist flow regimes, pressure gradients increased with increasing Reynolds number. Finally, the experimentally measured pressure gradient values were compared and are in good agreement with the theoretical values.

Engineering contributions to the life sciences

This paper discusses the contributions that physicians have made to the physical sciences. Some of the physicians mentioned by the author are William Gilbert who gave the first accurate treatise on magnetism, Thomas Young who gave us Young's modulus was also the first to discover the interference of light waves, Luigi Galvani who started the study on current electricity and bioelectricity, and Jean Louis Marie Poiseuille who was first to measure aortic pressure in dogs using a mercury U-tube manometer