The Effects of Different Levels of Ambient Oxygen in an Oxygen-Enriched Surgical Environment and Production of Surgical Fires

Surgical fires require an oxygen-enriched environment, a flammable substrate, and an ignition source. We hypothesized ambient oxygen concentration is proportional to the latency time to combustion and the incidence of surgical fires that are detected. We examined latency time and number of events, utilizing the VanCleave et al model of intraoral fire ignition under 60, 80, and 100% oxygen concentration and flow rates of 4 and 10 L/min. Results demonstrated that ambient oxygen concentration and flow rate correlated positively to the initiation of combustion. The number of combustion events with 60% oxygen was significantly lower than with both 80% (p = .0168) and 100% (p = .002). Likewise, the number of events with 80% oxygen was significantly lower than with 100% oxygen (p = .0019). Flow rate has a significant effect on the time to the first event (p = .0002), time to first audible pop (p = .0039), and time to first flash or fire (p < .0001). No combustion occurred at oxygen concentrations less than 60% or flows less than 4 L/min. We conclude that latency time to combustion is directly proportional to ambient oxygen concentration and flow rate. Minimum oxygen concentration and flow rate were identified in our model. Further research is indicated to determine the minimal clinical oxygen concentration and flow rate needed to support combustion of an intraoral fire in a patient.

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An Analysis of the Performance of a Variable Venturi-type Oxygen Mask

Anaesthesia and Intensive Care ◽

10.1177/0310057x8000800109 ◽

1980 ◽

Vol 8 (1) ◽

pp. 44-51 ◽

Cited By ~ 5

Author(s):

D. F. Woolner ◽

J. Larkin

Keyword(s):

Oxygen Concentration ◽

Flow Rate ◽

Oxygen Flow Rate ◽

Oxygen Flow ◽

Weighted Mean ◽

Flow Rates ◽

Oxygen Mask ◽

Inspired Oxygen ◽

Theoretical Performance

The theoretical performance of the Hudson Multivent mask is considered. A method is described of determining the flow-weighted mean inspired oxygen concentration produced by the mask. Using this method, it was found that the inspired oxygen concentration was predictable only at the 24% setting using the recommended flow rates, but that increasing the supplied-oxygen flow rates above the recommended levels resulted in the return of predictable function. At settings above 30% predictable function was found to be unlikely, whatever the supplied oxygen flow rate. Recommendations are made regarding the use of this device.

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STUDIES ON THE RELATIONSHIP BETWEEN WATER MOVEMENT AND WATER CHEMISTRY IN MIRES

Canadian Journal of Botany ◽

10.1139/b66-089 ◽

1966 ◽

Vol 44 (6) ◽

pp. 747-758 ◽

Cited By ~ 34

Author(s):

J. H. Sparling

Keyword(s):

Water Chemistry ◽

Oxygen Concentration ◽

Flow Rate ◽

Water Surface ◽

Water Movement ◽

Simple Diffusion ◽

Flow Rates ◽

Acidic Conditions ◽

The Relationship ◽

Iron And Manganese

Fifty-four sites were selected in a number of mires in Ontario, and rates of water movement were measured on a number of occasions. The rates of water movement ranged from less than 0.1 cm sec−1 to over 8 cm sec−1. The oxygen concentration of the mire waters increased with increasing flow rate, approaching saturation at rates over 1 cm sec−1. From a model it was shown that at a flow rate of less than 0.3–0.4 cm sec−1 the diffusion of oxygen into the water would be similar to simple diffusion into a stationary water surface, and because of the respiration of roots and microorganisms in the peat, the oxygen would tend to be depleted. Above flow rates of 0.4 cm sec−1 the water is agitated, and is continually replenished with oxygen from the atmosphere. Reduced states of iron and manganese were shown to be in solution at concentrations greater than 0.1 mg/1 only at low rates of water flow. The pH was also shown to increase with faster rates of water movement, the increase depending on the base status of the mire. Aluminium is in solution only in situations of low water movement where more acidic conditions are prevalent.

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Numerical simulation of the oxygen distribution in silicon melt for different argon gas flow rates during Czochralski silicon crystal growth process

MATEC Web of Conferences ◽

10.1051/matecconf/201820405013 ◽

2018 ◽

Vol 204 ◽

pp. 05013

Author(s):

Zumrotul Ida ◽

Jyh-Chen Chen ◽

Thi Hoai Thu Nguyen

Keyword(s):

Flow Pattern ◽

Oxygen Concentration ◽

Flow Rate ◽

Growth Process ◽

Gas Flow ◽

Silicon Crystal ◽

Gas Flow Rate ◽

Flow Rates ◽

Argon Gas ◽

Flow Motion

The effects of argon gas flow rate on the oxygen concentration in Czochralski (CZ) grown silicon crystal were examined. To analyze the influence of the argon gas flow rate in CZ growth process, a 200 mm length silicon single crystal was grown. Different argon gas flow rates are considered. The melt flow pattern, temperature and oxygen concentration distributions in the melt and crystal-melt interface are calculated. The results show that the transport of oxygen impurity is quite dependent on the flow motion in the melt. As the argon gas flow rate increases, there is no fundamental change in flow motion of the melt and the oxygen concentration decreases to a minimum value. When the argon gas flow rate increases further, the flow pattern under the melt-crystal interface starting changes and the oxygen concentration has increased after. Therefore, there is an optimum value for the argon gas flow rate for obtaining the lowest oxygen concentration in the melt.

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Hydraulic model of a water cooling system in a chemical plant

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19880788 ◽

1988 ◽

Vol 53 (4) ◽

pp. 788-806

Author(s):

Miloslav Hošťálek ◽

Jiří Výborný ◽

František Madron

Keyword(s):

Flow Rate ◽

Cooling System ◽

Cooling Water ◽

Graph Algorithm ◽

Automatic Generation ◽

Hydraulic Calculation ◽

Return Flow ◽

Flow Rates ◽

Pressure Losses ◽

Controlled Flow

Steady state hydraulic calculation has been described of an extensive pipeline network based on a new graph algorithm for setting up and decomposition of balance equations of the model. The parameters of the model are characteristics of individual sections of the network (pumps, pipes, and heat exchangers with armatures). In case of sections with controlled flow rate (variable characteristic), or sections with measured flow rate, the flow rates are direct inputs. The interactions of the network with the surroundings are accounted for by appropriate sources and sinks of individual nodes. The result of the calculation is the knowledge of all flow rates and pressure losses in the network. Automatic generation of the model equations utilizes an efficient (vector) fixing of the network topology and predominantly logical, not numerical operations based on the graph theory. The calculation proper utilizes a modification of the model by the method of linearization of characteristics, while the properties of the modified set of equations permit further decrease of the requirements on the computer. The described approach is suitable for the solution of practical problems even on lower category personal computers. The calculations are illustrated on an example of a simple network with uncontrolled and controlled flow rates of cooling water while one of the sections of the network is also a gravitational return flow of the cooling water.

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Geometrical Optimization of a Venturi-Type Microbubble Generator Using CFD Simulation and Experimental Measurements

Designs ◽

10.3390/designs5010004 ◽

2021 ◽

Vol 5 (1) ◽

pp. 4

Author(s):

Dillon Alexander Wilson ◽

Kul Pun ◽

Poo Balan Ganesan ◽

Faik Hamad

Keyword(s):

Water Flow ◽

Flow Rate ◽

Cfd Simulation ◽

Air Flow ◽

Bubble Diameter ◽

Diameter Ratio ◽

Experimental Measurements ◽

Cfd Model ◽

Flow Rates ◽

Throat Diameter

Microbubble generators are of considerable importance to a range of scientific fields from use in aquaculture and engineering to medical applications. This is due to the fact the amount of sea life in the water is proportional to the amount of oxygen in it. In this paper, experimental measurements and computational Fluid Dynamics (CFD) simulation are performed for three water flow rates and three with three different air flow rates. The experimental data presented in the paper are used to validate the CFD model. Then, the CFD model is used to study the effect of diverging angle and throat length/throat diameter ratio on the size of the microbubble produced by the Venturi-type microbubble generator. The experimental results showed that increasing water flow rate and reducing the air flow rate produces smaller microbubbles. The prediction from the CFD results indicated that throat length/throat diameter ratio and diffuser divergent angle have a small effect on bubble diameter distribution and average bubble diameter for the range of the throat water velocities used in this study.

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Comparison of different models to calculate the viscosity of biogas and biomethane in order to accurately measure flow rates for conformity assessment

Scientific Reports ◽

10.1038/s41598-021-81052-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Karine Arrhenius ◽

Oliver Büker

Keyword(s):

Binary Mixtures ◽

Flow Rate ◽

Correction Method ◽

Gas Mixtures ◽

Conformity Assessment ◽

Flow Rates ◽

Unknown Composition

AbstractThe study presents an optimised method to correct flow rates measured with a LFE flowmeter pre-set on methane while used for gas mixtures of unknown composition at the time of the measurement. The method requires the correction of the flow rate using a factor based on the viscosity of the gas mixtures once the composition is accurately known. The method has several different possible applications inclusive for the sampling of biogas and biomethane onto sorbent tubes for conformity assessment for the determination of siloxanes, terpenes and VOC in general. Five models for the calculation of the viscosity of the gas mixtures were compared and the models were used for ten binary mixtures and four multi-component mixtures. The results of the evaluation of the different models showed that the correction method using the viscosity of the mixtures calculated with the model of Reichenberg and Carr showed the smallest biases for binary mixtures. For multi-component mixtures, the best results were obtained when using the models of Lucas and Carr.

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Assessment of the Use of Humidified Nasal Cannulas for Oxygen Therapy in Patients with Epistaxis

ORL ◽

10.1159/000514460 ◽

2021 ◽

pp. 1-5

Author(s):

Jingjing Liu ◽

Tengfang Chen ◽

Zhenggang Lv ◽

Dezhong Wu

Keyword(s):

Flow Rate ◽

Oxygen Therapy ◽

Preliminary Investigation ◽

Nasal Cannula ◽

Low Flow ◽

Antiplatelet Drugs ◽

Flow Rates ◽

The Past ◽

Oxygen Inhalation ◽

Significant Difference

Introduction: In China, nasal cannula oxygen therapy is typically humidified. However, it is difficult to decide whether to suspend nasal cannula oxygen inhalation after the nosebleed has temporarily stopped. Therefore, we conducted a preliminary investigation on whether the use of humidified nasal cannulas in our hospital increases the incidence of epistaxis. Methods: We conducted a survey of 176,058 inpatients in our hospital and other city branches of our hospital over the past 3 years and obtained information concerning their use of humidified nasal cannulas for oxygen inhalation, nonhumidified nasal cannulas, anticoagulant and antiplatelet drugs, and oxygen inhalation flow rates. This information was compared with the data collected at consultation for epistaxis during these 3 years. Results: No significant difference was found between inpatients with humidified nasal cannulas and those without nasal cannula oxygen therapy in the incidence of consultations due to epistaxis (χ2 = 1.007, p > 0.05). The same trend was observed among hospitalized patients using anticoagulant and antiplatelet drugs (χ2 = 2.082, p > 0.05). Among the patients with an inhaled oxygen flow rate ≥5 L/min, the incidence of ear-nose-throat (ENT) consultations due to epistaxis was 0. No statistically significant difference was found between inpatients with a humidified oxygen inhalation flow rate <5 L/min and those without nasal cannula oxygen therapy in the incidence of ENT consultations due to epistaxis (χ2 = 0.838, p > 0.05). A statistically significant difference was observed in the incidence of ENT consultations due to epistaxis between the low-flow nonhumidified nasal cannula and nonnasal cannula oxygen inhalation groups (χ2 = 18.428, p < 0.001). The same trend was observed between the 2 groups of low-flow humidified and low-flow nonhumidified nasal cannula oxygen inhalation (χ2 = 26.194, p < 0.001). Discussion/Conclusion: Neither high-flow humidified nasal cannula oxygen inhalation nor low-flow humidified nasal cannula oxygen inhalation will increase the incidence of recurrent or serious epistaxis complications; the same trend was observed for patients who use anticoagulant and antiplatelet drugs. Humidification during low-flow nasal cannula oxygen inhalation can prevent severe and repeated epistaxis to a certain extent.

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Net-exergetic, hydraulic and thermal optimization of coaxial heat exchangers using fixed flow conditions instead of fixed flow rates

Geothermal Energy ◽

10.1186/s40517-021-00201-3 ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Tobias Blanke ◽

Markus Hagenkamp ◽

Bernd Döring ◽

Joachim Göttsche ◽

Vitali Reger ◽

...

Keyword(s):

Reynolds Number ◽

Laminar Flow ◽

Mass Flow ◽

Flow Rate ◽

Heat Exchangers ◽

Circular Ring ◽

Flow Conditions ◽

Flow Rates ◽

Mass Flow Rates ◽

Pipe Radius

AbstractPrevious studies optimized the dimensions of coaxial heat exchangers using constant mass flow rates as a boundary condition. They show a thermal optimal circular ring width of nearly zero. Hydraulically optimal is an inner to outer pipe radius ratio of 0.65 for turbulent and 0.68 for laminar flow types. In contrast, in this study, flow conditions in the circular ring are kept constant (a set of fixed Reynolds numbers) during optimization. This approach ensures fixed flow conditions and prevents inappropriately high or low mass flow rates. The optimization is carried out for three objectives: Maximum energy gain, minimum hydraulic effort and eventually optimum net-exergy balance. The optimization changes the inner pipe radius and mass flow rate but not the Reynolds number of the circular ring. The thermal calculations base on Hellström’s borehole resistance and the hydraulic optimization on individually calculated linear loss of head coefficients. Increasing the inner pipe radius results in decreased hydraulic losses in the inner pipe but increased losses in the circular ring. The net-exergy difference is a key performance indicator and combines thermal and hydraulic calculations. It is the difference between thermal exergy flux and hydraulic effort. The Reynolds number in the circular ring is instead of the mass flow rate constant during all optimizations. The result from a thermal perspective is an optimal width of the circular ring of nearly zero. The hydraulically optimal inner pipe radius is 54% of the outer pipe radius for laminar flow and 60% for turbulent flow scenarios. Net-exergetic optimization shows a predominant influence of hydraulic losses, especially for small temperature gains. The exact result depends on the earth’s thermal properties and the flow type. Conclusively, coaxial geothermal probes’ design should focus on the hydraulic optimum and take the thermal optimum as a secondary criterion due to the dominating hydraulics.

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Effects of Sprinkler Flow Rate on Physiological, Behavioral and Production Responses of Nili Ravi Buffaloes during Subtropical Summer

Animals ◽

10.3390/ani11020339 ◽

2021 ◽

Vol 11 (2) ◽

pp. 339

Author(s):

Musa Bah ◽

Muhammad Afzal Rashid ◽

Khalid Javed ◽

Talat Naseer Pasha ◽

Muhammad Qamer Shahid

Keyword(s):

Heat Stress ◽

Milk Yield ◽

Flow Rate ◽

Rectal Temperature ◽

Latin Square ◽

Flow Rates ◽

Group Water ◽

Humidity Index ◽

Daily Milk Yield ◽

Daily Milk

Water buffaloes wallow in water to combat heat stress during summer. With the decreasing reservoirs for wallowing, the farmers use sprinklers to cool the buffaloes in Pakistan. These sprinklers use a large quantity of groundwater, which is becoming scarce. The objective of the current study was to determine the effect of different sprinkler flow rates on the physiological, behavioral, and production responses of Nili Ravi buffaloes during summer. Eighteen buffaloes were randomly subjected to three sprinkler flow rate treatments in a double replicated 3 × 3 Latin square design. The flow rates were 0.8, 1.25, and 2.0 L/min. During the study, the average afternoon temperature humidity index was 84.6. The 1.25 and 2.0 L/min groups had significantly lower rectal temperature and respiratory rates than the 0.8 L/min group. Water intake was significantly higher in the 0.8 L/min group. Daily milk yield was higher in the 1.25 and 2.0 L/min groups than in the 0.8 L/min group. These results suggested that the sprinkler flow rates > 0.8 L/min effectively cooled the buffaloes. The sprinkler flow rate of 1.25 L/min appeared to be more efficient, as it used 37.5% less water compared to the 2.0 L/min.

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Laser-Doppler Velocimetry Measurements Inside a Backward Curved Centrifugal Fan

International Journal of Rotating Machinery ◽

10.1155/s1023621x01000161 ◽

2001 ◽

Vol 7 (3) ◽

pp. 173-181

Author(s):

Tong-Miin Liou ◽

Meng-Yu Chen

Keyword(s):

Flow Rate ◽

Turbulence Intensity ◽

Laser Doppler Velocimetry ◽

Reverse Flow ◽

Flow Region ◽

Design Flow ◽

Laser Doppler ◽

Centrifugal Fan ◽

Doppler Velocimetry ◽

Flow Rates

Laser-Doppler velocimetry (LDV) measurements are presented of relative mean velocity and turbulence intensity components inside the impeller passage of a centrifugal fan with twelve backward curved blades at design, under-design, and over-design flow rates. Additional LDV measurements were also performed at the volute outlet to examine the uniformity of the outlet flow for the three selected flow rates. Complementary flow visualization results in the tongue region are further presented. It is found that the number of characteristic flow regions and the average turbulence level increase with decreasing air flow rate. For the case of under-design flow rate, there are a through-flow region on the suction side, a reverse flow region on the pressure side, and a shear layer region in between. The corresponding average turbulence intensity is as high as 9.1% of blade tip velocity.

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