In-line Flow Meters Research Articles

Accuracy of a hand-held resistance-free flowmeters for flow adjustments of Hirst-Type pollen traps

The Hirst-type pollen trap (1952) is the most common device for aerobiological measurements of pollen and fungal spores in ambient air. In the 1960s the in-line flowmeter was removed and studies since then showed considerable variability in the airflow pumped through the instrument when using hand-held rotameters with an internal airflow resistance to adjust flowrates. To avoid this problem, our study compared the variability of airflow rates of Hirst-type traps when using commercially-available low-resistance airflow meters (heat anemometers) at various timescales. Experiments were conducted in Munich (Germany) and Payerne (Switzerland), using 4 different easyFlux® instruments and 6 Hirst-type pollen traps. Measurements were taken on an hourly basis from dawn to dusk at both locations, and in addition at Payerne, weekly observations over a period of one year. When using the common hand-held rotameters (with airflow resistance) the flow was 28.3% lower than with resistance-free flowmeter (i.e., measured 10 L/min which was in reality 12.8 L/min). The coefficient of variation between the four easyFlux® devices ranged from 0.32% to 1.55% over one day and from 2.88% to 8.17% over an entire year. Some of the traps showed surprising flow variations during the day. Furthermore, flowrates deviated more when measurements were made at the point where the double-sided tape is behind the orifice than elsewhere on the drum. The measurements away from this point are representative of the flow rates for most of the period of operation and flow calibration should thus be carried out away from this point, contrary to the current procedure.

Development and Validation of an In Situ Groundwater Abstraction Sensor Network, Hydrologic Statistical Model, and Blockchain Trading Platform: A Demonstration in Solano County, California.

Megadrought in the western United States is jeopardizing water security. Groundwater regulations, such as California's Sustainable Groundwater Management Act (SGMA), aim to preserve groundwater resources in overdrafted basins. Water agencies must establish sufficient monitoring systems to measure local groundwater abstraction and devise plans to moderate groundwater use. However, few technologies are available to monitor and regulate groundwater abstraction spatially and temporally. In this study, we deployed satellite-connected electrical current sensors on 11 agricultural groundwater pumps in Solano County, California over 2019-2022. A high correlation (R 2 = 0.706) was found between the in situ sensors and in-line flow meters. We then combine in situ sensor data with a land surface model to develop a multiple linear regression model of groundwater abstraction and groundwater level. Using a 10-fold cross-validation, it is found that our predictive groundwater abstraction model has approximately a 3.5% bias and a mean absolute error of 1.21 acre-feet, while our predictive groundwater level model has approximately 4.2% bias and about 5.9 acre-feet mean absolute error. Finally, we integrated these data with a blockchain-based groundwater credit trading platform to demonstrate how such a tool could be used for SGMA compliance.

Modeling Surface Roughness-Related Uncertainties of Leaky Lamb Wave Clamp-on Ultrasonic Flowmeters

Transit time clamp-on ultrasonic flowmeters (UFMs) are widely used in industry due to their ease of installation. However, these ultrasonic clamp-on flowmeters are also known to be less accurate than ultrasonic inline flowmeters because of the uncertainties induced by the installation process. Amongst the installation-related parameters that influence the measurement uncertainties, internal pipe wall roughness is one of the most significant but uncontrollable parameters. The effect of roughness on accuracy can be reduced by operating the flowmeter at a longer wavelength. This article investigates the effect of roughness on a clamp-on UFM using low-frequency (200 kHz) leaky Lamb waves. This results in operation at roughly five times lower frequency compared with conventional clamp-on UFMs. The ultrasonic signals of this leaky Lamb wave UFM were simulated using the 2-D finite-element (FE) analysis. Using the simulated signals, the roughness effects on the uncertainties were quantified. The simulation results show that the uncertainty related to pipe wall roughness of leaky Lamb wave UFMs is approximately half that of conventional UFMs for corroded pipe walls with rms value larger than 0.1 mm (0.2, 0.35, and 0.5 mm). Demonstration experiments were also carried out to detect leaky Lamb wave using an electromagnetic acoustic transducer (EMAT). The experiment shows that the simulation correctly captures all the physics of the wave propagation and that we, therefore, can trust the simulation results with incorporated roughness.

CubeSats Enable High Spatiotemporal Retrievals of Crop-Water Use for Precision Agriculture

Remote sensing based estimation of evapotranspiration (ET) provides a direct accounting of the crop water use. However, the use of satellite data has generally required that a compromise between spatial and temporal resolution is made, i.e., one could obtain low spatial resolution data regularly, or high spatial resolution occasionally. As a consequence, this spatiotemporal trade-off has tended to limit the impact of remote sensing for precision agricultural applications. With the recent emergence of constellations of small CubeSat-based satellite systems, these constraints are rapidly being removed, such that daily 3 m resolution optical data are now a reality for earth observation. Such advances provide an opportunity to develop new earth system monitoring and assessment tools. In this manuscript we evaluate the capacity of CubeSats to advance the estimation of ET via application of the Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) retrieval model. To take advantage of the high-spatiotemporal resolution afforded by these systems, we have integrated a CubeSat derived leaf area index as a forcing variable into PT-JPL, as well as modified key biophysical model parameters. We evaluate model performance over an irrigated farmland in Saudi Arabia using observations from an eddy covariance tower. Crop water use retrievals were also compared against measured irrigation from an in-line flow meter installed within a center-pivot system. To leverage the high spatial resolution of the CubeSat imagery, PT-JPL retrievals were integrated over the source area of the eddy covariance footprint, to allow an equivalent intercomparison. Apart from offering new precision agricultural insights into farm operations and management, the 3 m resolution ET retrievals were shown to explain 86% of the observed variability and provide a relative RMSE of 32.9% for irrigated maize, comparable to previously reported satellite-based retrievals. An observed underestimation was diagnosed as a possible misrepresentation of the local surface moisture status, highlighting the challenge of high-resolution modeling applications for precision agriculture and informing future research directions.

Non-invasive estimation of domestic hot water usage with temperature and vibration sensors

Electric water heaters are responsible for a large portion of electricity consumption and water usage in the domestic sector. Smart water heaters alleviate the strain on the electricity supply grid and reduce water consumption through behavioural change, but the installation of in-line flow meters is inconvenient and expensive. A non-invasive water flow meter is proposed as an alternative. Non-invasive flow measurement is more common for high flow rates in the industrial sector than for domestic applications. Various non-invasive water measurement methods are investigated in the context of domestic hot water, and a combination of thermal- and vibration-sensing is proposed. The proposed solution uses inexpensive, easily installable, non-invasive sensors and a novel algorithm to provide the same flow measurement accuracy as existing in-line meters. The algorithm detects the beginning and end of water consumption events with an accuracy of 95.6%. Quantitative flow rate estimation was possible for flow rates greater than 5 L min−1 with an accuracy of 89%, while volumetric usage estimation had an accuracy of more than 93%. The algorithm limitations were applied to field data, revealing that water consumption could be detected with an error of less than 12% within the limitations of the proposed algorithm. The paper presents a successful proof of concept for a non-invasive alternative to domestic hot water flow rate measurement.

Fourier Collocation Approach With Mesh Refinement Method for Simulating Transit-Time Ultrasonic Flowmeters Under Multiphase Flow Conditions.

A numerical model for transit-time ultrasonic flowmeters operating under multiphase flow conditions previously presented by us is extended by mesh refinement and grid point redistribution. The method solves modified first-order stress-velocity equations of elastodynamics with additional terms to account for the effect of the background flow. Spatial derivatives are calculated by a Fourier collocation scheme allowing the use of the fast Fourier transform, while the time integration is realized by the explicit third-order Runge-Kutta finite-difference scheme. The method is compared against analytical solutions and experimental measurements to verify the benefit of using mapped grids. Additionally, a study of clamp-on and in-line ultrasonic flowmeters operating under multiphase flow conditions is carried out.

In vitro assessment of small charged pharmaceutical aerosols in a model of a ventilated neonate

Aerosolized medications may benefit infants receiving mechanical ventilation; however, the lung delivery efficiency of these aerosols is unacceptably low. In vitro experiments were conducted to evaluate aerosol delivery through conventional and modified ventilation systems to the end of a 3mm endotracheal tube (ETT) under steady state and realistic cyclic flow conditions. System modifications were employed to investigate the use of small charged particles and included streamlined components, a reduction in nebulizer liquid flow rate, synchronization with inspiration, and implementation of a previously designed low-flow induction charger (LF-IC), which was further modified in this study. Cyclic flow experiments implemented a modern ventilator with bias airflow and an inline flow meter, both of which are frequently excluded from in vitro tests but included in clinical practice. The modified LF-IC system demonstrated superior delivery efficiency to the end of the ETT (34%) compared with the commercial system (~1.3%) operating under cyclic ventilation conditions. These findings indicate that commercial systems still provide very low lung delivery efficiencies despite decades of innovation. In contrast, the modified system increased dose delivery to the end of the ETT by 26-fold. Despite initial concerns, the charged aerosol could be efficiently delivered through the small diameter ETT and reach the lungs. Future studies will be required to determine if the applied particle charge can eliminate expected high exhalation aerosol loss and will require the development of a realistic lung model.

Nutrient contributions and biogas potential of co-digestion of feedstocks and dairy manure

This study focused on collection of data on nutrient flow and biogas yield at a commercial anaerobic digester managed with dairy manure from a 1000 cow dairy and co-digestion of additional feedstocks. Feedstocks included: blood, fish, paper pulp, out of date beverages and grease trap waste. Mass flow of inputs and outputs, nutrient concentration of inputs and outputs, and biogas yield were obtained. It was determined that manure was the primary source of nutrients to the anaerobic digester when co-digested with feedstocks. The percentage of contribution from manure to the total nutrient inputs for total nitrogen, ammonia-nitrogen, phosphorus and total solids was 46.3%, 67.7%, 32.8% and 23.4%, respectively. On average, manure contributed the greatest amount of total nitrogen and ammonia-nitrogen. Grease trap waste contributed the greatest amount of phosphorus and total solids at approximately 50%. Results demonstrated that a reliable estimate of nutrient inflow could be obtained from the product of the nutrient analyses of a single daily composite of influent subsamples times the total daily flow estimated with an in-line flow meter. This approach to estimate total daily nutrient inflow would be more cost effective than testing and summing the contribution of individual feedstocks. Data collected after liquid-solid separation confirmed that the majority (>75%) of nutrients remain with the liquid effluent portion of the manure stream. It was demonstrated that the ash concentration in solids before and after composting could be used to estimate the mass balance of total solids during the compost process. This data confirms that biogas or methane yield could be accurately measured from the ratio of % volatile solids to % total solids.

Note: Ultrasonic liquid flow meter for small pipes

An ultrasonic flow meter for small pipes is presented. For metal pipe diameter smaller than 10 mm, clamp-on ultrasonic contrapropagation flow meters may encounter difficulties if cross talk or the short acoustic path contributes to large uncertainty in transit time measurement. Axial inline flow meters can avoid these problems, but they may introduce other problems if the transducer port is not properly positioned. Three types of pipe connecting tees are compared using the computational fluid dynamics (CFD) method. CFD shows the 45° tee has more uniform velocity distribution over the measuring section. A prototype flow meter using the 45° tee was designed and tested. The zero flow experiment shows the flow meter has a maximum of 0.002 m∕s shift over 24 h. The flow meter is calibrated by only 1 meter factor. After calibration, inaccuracy lower than 0.1% of reading was achieved in the laboratory, for a measuring range from 15 to 150 g∕s (0.29 to 2.99 m∕s; Re = 2688 to 26,876).

Validation of a 3D computational fluid–structure interaction model simulating flow through an elastic aperture

This work presents a validation of a fluid–structure interaction computational model simulating the flow conditions in an in vitro mock heart chamber modeling mitral valve regurgitation during the ejection phase during which the trans-valvular pressure drop and valve displacement are not as large. The mock heart chamber was developed to study the use of 2D and 3D color Doppler techniques in imaging the clinically relevant complex intra-cardiac flow events associated with mitral regurgitation. Computational models are expected to play an important role in supporting, refining, and reinforcing the emerging 3D echocardiographic applications. We have developed a 3D computational fluid–structure interaction algorithm based on a semi-implicit, monolithic method, combined with an arbitrary Lagrangian–Eulerian approach to capture the fluid domain motion. The mock regurgitant mitral valve corresponding to an elastic plate with a geometric orifice, was modeled using 3D elasticity, while the blood flow was modeled using the 3D Navier–Stokes equations for an incompressible, viscous fluid. The two are coupled via the kinematic and dynamic conditions describing the two-way coupling. The pressure, the flow rate, and orifice plate displacement were measured and compared with numerical simulation results. In-line flow meter was used to measure the flow, pressure transducers were used to measure the pressure, and a Doppler method developed by one of the authors was used to measure the axial displacement of the orifice plate. The maximum recorded difference between experiment and numerical simulation for the flow rate was 4%, the pressure 3.6%, and for the orifice displacement 15%, showing excellent agreement between the two.

A Three-Dimensional Computational Fluid Dynamics Model of Regurgitant Mitral Valve Flow: Validation Against In Vitro Standards and 3D Color Doppler Methods

3D color Doppler echocardiography has recently been employed to evaluate 3D proximal isovelocity surface area (PISA) and vena contracta (VC) area measures of regurgitant valve severity. Computational fluid dynamics (CFD) modeling may provide insight into the strengths and limitations of emerging 3D color Doppler applications for the quantification of mitral regurgitation (MR). The objective of this study is to evaluate a recently developed CFD simulation of regurgitant mitral jets under tailored hemodynamic conditions. Moderate MR (30 mL/beat) and severe MR (70 mL/beat) were simulated using an in vitro flow loop with an imaging chamber configured to model a regurgitant mitral orifice. A novel application of a 3D CFD model based on a finite element method approximation of the Navier–Stokes equation was used to simulate the regurgitant flow conditions. The CFD derived peak transorifice pressure gradient and velocity were compared against in vitro measurement standards. CFD simulation of proximal regurgitant flow events were compared against 2D and 3D color Doppler PISA and VC measurements. Compared to an in-line flow meter reference, the CFD model provided an accurate estimate of peak transorifice flow velocity (mean 459 vs. 442 m/s, respectively; relative error 5.7%). Compared to high-fidelity pressure transducers, the CFD model provided accurate estimates of peak transorifice pressure gradient (mean 90 vs. 85 mmHg, respectively; relative error 10.4%). Compared to 3D color Doppler PISA measures, the CFD model of isovelocity surface area was larger (relative difference 7–23%). The error was greatest for higher flow conditions. When compared to the actual orifice area, the 3D Doppler VC area was larger (3–14% relative error), whereas the CFD VC area was smaller (8–9% relative error) and more consistent with the expected reduction in area due to transvalvular flow compression. 3D CFD simulations of complex intracardiac flow events are accurate when compared to in vitro pressure and flow measures and are consistent with recently introduced 3D echocardiographic flow quantification methods. Future studies may employ validated CFD models to assess the strengths and limitations of emerging 3D color Doppler applications.

Self-priming Hemodynamic Reservoir and Inline Flow Meter for a Cardiopulmonary Bypass Simulation

Simulator exercises are used at Midwestern University to augment academic and laboratory training toward consolidating particular skills, increasing situation awareness, and preparing the student for practice within the team environment of an operating room. This paper describes an enhanced cardiopulmonary bypass simulator consisting of a self-priming hemodynamic reservoir that includes an inline flow meter. A typical cardiopulmonary bypass adult perfusion circuit was assembled using a roller pump console and integrated oxygenator/heat exchanger/reservoir and primed with 2 liters of water. For patient simulation, a soft-sided reservoir bag was mounted onto an inclined platform. A 1-liter soft-sided bag was placed just above the reservoir, providing an overflow reservoir. The priming line extended to the head of the mannequin. The arterial, venous, and suction lines extended through the open chest. The primed perfusion circuit was connected to ports on the filled reservoir bag. To test the patient simulation, the arterial pump output was adjusted to flow rates ranging from 1–7 liters per minute, with a complete interruption (to zero flow) between each test run. An inline flow meter was added to the bypass circuit and an analog to digital converter board was used to pass flow data into the computer-based simulation program. The use of an inclined hemodynamic reservoir bag proved to be self-priming and functional without problems over a wide range of flows tested. By including a reservoir with the mannequin, plus processing and displaying real-time flow data using the CPB-Sim simulation program, a higher fidelity and more realistic simulation experience was created.

Chronic resistance training attenuates age‐associated endothelial dysfunction in coronary arteries of aging rats

Age is associated with reduction endothelial‐dependent vasorelaxation in human and animal coronary arteries. Endurance exercise training has been shown to reverse this and to protect against myocardial ischemia/reperfusion in isolated rat hearts in part through improved coronary flow. Although resistance exercise training may be prescribed in aged individuals to enhance quality of life, little is known regarding the effects of this type of exercise on coronary endothelial function. Therefore, aged (24 mo) male, Fisher 344 rats were divided into two groups: Aged Sedentary (AS, n=8), and Aged Trained (AT, n=10). Resistance exercise training consisted of climbing a 1 m wire ladder, at an 85o angle, 3d/wk for 7 weeks with increasing weight added to the tail. Coronary flow was measured in isolated, perfused hearts using the Langendorff model and constant pressure. After a 30 minute stabilization period, changes in coronary flow were measured following bolus injections of bradykinin (BK, 10−12‐10−4) using an in‐line flow meter. Coronary flows were significantly (P<0.05) improved at high doses of BK in AT versus AC. In conclusion, these results suggest that resistance exercise training in aged rats attenuates age‐associated endothelial dysfunction in coronary arteries. Supported by NIH R15 HL082649‐01 (MBH) and the Borgenicht Program for Aging Studies and Exercise Science (MBH).

Technical Note: Therapeutic Cessation of Lactation of Staphylococcus aureus-Infected Mammary Quarters

The objective of the present study was to compare the ability of chlorhexidine and povidone-iodine to cause cessation of lactation in Staphylococcus aureus-infected mammary quarters, assess milk production in the treated quarter in the subsequent lactation, and evaluate whether microbiological cure was obtained. Fourteen mid- to late-lactation Holstein-Friesian dairy cattle from the Washington State University dairy herd with single mammary quarter S. aureus intramammary infections were studied. Cows were randomly assigned to one of two treatment groups, povidone-iodine or chlorhexidine. Cows in the povidone-iodine group were infused with 120ml of 5% povidone-iodine solution (0.5% iodine) after complete milk-out. Chlorhexidine-treated cows were infused with a proprietary chlorhexidine suspension after two milkings 24h apart. Treated mammary quarters were not milked for the rest of the lactation. Milk production from each mammary quarter (kg of milk/quarter) was measured using in-line volume flow meters for 5 consecutive days before treatment and again at the start of the subsequent lactation. Povidone-iodine caused permanent cessation of lactation in the treated quarter, whereas 71% of the chlorhexidine-treated mammary quarters returned to function in the subsequent lactation. Hence, if the primary objective is to eliminate the mammary quarter from lactation, and thereby presumably lower the risk of herdmates acquiring new S. aureus intramammary infection, then povidone-iodine appears to be the best of the two methods. No difference in total milk production between lactation one and two in either group was found, suggesting that permanent loss of a quarter was not detrimental to overall milk production.

Protection against ventricular fibrillation by the PAF antagonist, BN-50739, involves an ischaemia-selective mechanism.

The platelet-activating factor (PAF) antagonist BN-50739 can suppress certain cardiac arrhythmias. PAF is released from ischaemic myocardium and may contribute to initiation of ischaemia-induced ventricular fibrillation (VF). In this study we characterised the action of BN-50739 on left regional ischaemia-induced VF and examined whether effects are mediated within the ischaemic territory, or are nonspecific. In rat isolated Langendorff perfused hearts (n = 12/group), 10 microM BN-50739 reduced the incidence of ischaemia-induced VF from 75 to 17% (p<0.05). This was accompanied by QT widening and an increase in coronary flow. Heart rate and PR interval were not affected by the drug. In separate studies, isolated rat hearts were perfused by using a dual-lumen tube that allows independent delivery of solution to the left and right coronary beds. Successful regional localisation of drug delivery was confirmed by observing, before ischaemia, a regionally selective increase in coronary flow (p<0.05), measured by using two in-line flow meters. Protection against ischaemia-induced VF (p<0.05) was achieved by pretreatment with BN-50739, delivered selectively and entrapped within the involved region, but not when the drug was delivered to the uninvolved region. In conclusion, BN-50739 protects against ischaemia-induced VF by eliciting a pharmacologic action in the involved (ischaemic) myocardium. This supports the hypothesis that BN-50739 suppresses an arrhythmogenic effect of endogenous PAF released within the ischaemic tissue.

Devolatilization of Polymer Solutions

Abstract A simulator to emulate the working of a counter-rotating twin screw extruder was constructed for studying devolatilization (DV) of reactive polymer solutions. The rate of the release of the volatiles was measured by an in-line mass flow meter. The operating pressure and solution temperature were measured by a pressure transducer and a thermocouple. The vapor sample compositions were determined by UV spectrophotometer. The transesterification of ethylene-vinyl acetate copolymer with 3-phenyl 1-propanol in 1-nonane solution was chosen as a model reaction. The volumetric mass transfer coefficient K1A was determined at various temperatures, pressures, shaft speeds and sample sizes. The effect of the reaction on K1A was also examined. It was found that K1A of the solvent (1-nonane) increases significantly with a decrease in operating pressure, and that it also increases appreciably with shaft speed, whereas temperature and the initial sample size have little effect on it. The reaction shows undetectable effect on K1A of the inert solvent.

Role of cardiac mast cells in complement C5a-induced myocardial ischemia.

Activated complement component C5a causes myocardial ischemia mediated by thromboxane (Tx) A2 and leukotrienes C4/D4. Blood cells are not involved in either the mediator release or the myocardial effects of C5a, suggesting that a C5a-sensitive, cardiac resident inflammatory cell is responsible. The goals of this study were to determine whether 1) cardiac mast cell activation accompanies the C5a response, 2) inhibition of mast cell degranulation inhibits the response, and 3) histamine release plays a role in the C5a-induced myocardial ischemia. The left anterior descending coronary artery (LAD) of open-chest pigs (n = 13) was perfused with arterial blood at constant pressure (95 mmHg). Coronary blood flow (CBF) was measured (in-line flowmeter) and regional function [percent segment shortening (%SS)] determined with sonomicrometry. A coronary vein was cannulated for measurement of plasma TxB2 and histamine (a marker of mast cell degranulation). Intracoronary C5a (500 ng) decreased coronary blood flow (45% of preinfusion levels) and LAD %SS (65% of preinfusion) and was accompanied by increases in coronary venous TxB2 (delta 63.3 ng/ml) and histamine (delta 200 nM). Mast cell inhibition with lodoxamide (2 mg/kg iv, n = 8) attenuated the C5a-induced fall in CBF (14 vs. 53% decrease, P < 0.01) and %SS (10 vs. 38% decrease, P < 0.01) and also reduced the C5a-induced increase in both coronary venous histamine (delta 26 vs. 278 nM, P < 0.05) and TxB2 (delta 0.34 vs. 63.3 ng/ml, P < 0.01). However, histamine H1 (pyrilamine) and H2 (ranitidine) receptor blockade had no effect on the C5a-induced fall in CBF or LAD %SS.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of positive expiratory pressure on peritoneovenous shunt flow.

Cirrhotic patients with peritoneovenous shunts may require mechanical ventilation. Despite the importance of flow to shunt patency and the relevance of intrathoracic pressure to that flow, the relationship between shunt flow and positive airway pressure has not been documented. To study the effects of positive expiratory pressure (PEEP) on shunt flow, models of ascites (n = 8) were created in adult male mongrel dogs. Each animal was anesthetized, intubated, and mechanically ventilated. Peritoneovenous shunts with in-line electromagnetic flow meters were surgically placed. Shunt flow, central venous pressure (CVP), and intraabdominal pressure (IAP) were monitored. Initial intraabdominal pressures were adjusted by infusion of warmed saline and positive expiratory airway pressures were added in increments. Changes in pressures (IAP, CVP) and shunt flow were tabulated and analyzed with linear and polynomial regression. Intraabdominal and central venous pressures increased linearly with PEEP at different rates such that IAP-CVP varied inversely with PEEP. Shunt flow varied inversely as a polynomial function of PEEP. Analyses of these relationships allowed creation of a nomogram which can be interpolated to indicate required intraabdominal pressure needed to maintain shunt flow throughout the clinically useful range of positive airway pressure.

Sanitary Evaluation of Target Flowmeter Used in a Dairy Processing Plant

A target flowmeter, used to measure raw milk flow, was examined for sanitary conditions in a university dairy plant 10 times over a period of eight weeks. The flowmeter connection was swabbed at four different locations along the dairy plant connection at four different times during the work day: i) after chlorine sanitization, before product; ii) after product, before cleaning in place (CIP); iii) after CIP, before acid sanitization; and iv) after acid sanitization, at end of day. Samples were plated in duplicate on standard plate count agar and on violet red bile agar. After routine CIP cleaning and sanitization procedures, bacterial counts were low. Additionally, no finished product contamination problems were detected over the 7 months of flowmeter use as shown by routine quality control tests on pasteurized milk which had flowed past the in-line meter as raw milk. These results indicate that normal cleaning and sanitization procedures were adequate for the in-line flowmeter.

The influence of perfusate viscosity, RBC deformability and drag on the function of an isolated perfused rat kidney

There is increasing clinical interest in improving blood rheology to optimize organ function, but studies correlating the two are scarce. To study this, rat kidneys were perfused in vitro at 37°C at a constant mean renal arterial pressure of 160 mm Hg. The perfusate consisted of an oxygenated Krebs HCO 3 buffer containing 1 mg/ml glucose, 0.5 mg/ml creatinine, amino acids, [ 3H]inulin (marker for GFR), 2.5 g/dl albumin, and 10 or 20% hematocrit. In some experiments, RBC were made nondeformable by heating at 50°C for 20 min. Deformability was measured by an ektacytometer. In other experiments, 0.001% of an anionic polyacrylamide (Separan), a drag-reducing agent, was added to the perfusate. Viscosity was measured with a cone and plate viscometer, [Na +] with a flame spectrophotometer, and perfusate flow with a Brooks in-line flowmeter. Other functional parameters, GFR, urine flow, RPF, and reabsorption of sodium and water, were also measured. The results indicate that (1) making RBC nondeformable or increasing viscosity by increasing hematocrit reduces renal function, and (2) addition of a drag-reducing agent improves renal function at 20% hematocrit. We conclude that rheologic manipulation of a perfusate solution can alter flow and renal function.