scholarly journals Comparison of H2S Gas Sensors: A Sensor Management Procedure for Sewer Monitoring

2021 ◽  
Vol 13 (19) ◽  
pp. 10779
Author(s):  
Micaela Pacheco Fernández ◽  
Daneish Despot ◽  
Matthias Barjenbruch
Keyword(s):  
Gas Sensors ◽  
Graphical Analysis ◽  
Application Site ◽  
Sensor Management ◽  
Data Logger ◽  
Statistical Measures ◽  
Management Procedure ◽  
Gas Measurements ◽  
Access To Data ◽  
Online Sensors

Hydrogen sulphide (H2S) emissions are one of the major problems associated with sewer networks. This gas, with its characteristic smell of rotten eggs is highly toxic and leads to the corrosion of sewer infrastructures. To protect cities and ensure the safety of sewer workers, sewers are commonly monitored using H2S gas sensors. In this work, three commercial H2S gas sensors for air quality monitoring were compared at two different sites in Berlin, Germany. Two of the sensors provide online access to data, while the other one is a data logger. Moreover, based on statistical measures (RMSE, MAE, MB, and a graphical analysis), we evaluated whether a rotation/exchange between data logger (reference) and online sensors is possible without significant differences in the gas measurements. Experimental evaluation revealed that measurement differences are dependent on the H2S concentration range. The deviation between sensors increases as the H2S concentration rises. Therefore, the interchange between reference and online sensors depends on the application site and the H2S levels. At lower ranges (0–10 ppm) there were no observed problems. Finally, to support practitioners on-site, a management procedure in the form of a decision-making tool is proposed for assessing whether gas sensors should be exchanged/rotated.

scholarly journals Comparison of Online Sensors for Liquid Phase Hydrogen Sulphide Monitoring in Sewer Systems

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1876
Author(s):  
Daneish Despot ◽  
Micaela Pacheco Fernández ◽  
Matthias Barjenbruch
Keyword(s):  
Liquid Phase ◽  
Gas Sensors ◽  
High Sensitivity ◽  
Laboratory Method ◽  
Control Measures ◽  
Monitoring And Control ◽  
Sewer Systems ◽  
H2s Emission ◽  
H2s Detection ◽  
Online Sensors

Hydrogen sulfide (H2S) related to wastewater in sewer systems is known for causing significant problems of corrosion and odor nuisance. Sewer systems severely affected by H2S typically rely on online H2S gas sensors for monitoring and control. However, these H2S gas sensors only provide information about the H2S emission potential at the point being monitored, which is sometimes inadequate to design control measures. In this study, a comparison of three market-ready online sensors capable of liquid-phase H2S detection in sewer systems was assessed and compared. Two of the three sensors are based on UV/Vis spectrophotometry, while the other adapted the design and principles of a Clark-type electrochemical microsensor. The H2S measurements of the sensors were statistically compared to a standard laboratory method at first. Following that, the performance of the online sensors was evaluated under realistic sewer conditions using the Berlin Water Company (BWB) research sewer pilot plant. Test applications representing scenarios of typical H2S concentrations found in sulfide-affected sewers and during control measures were simulated. The UV/Vis spectrometers showed that the performance of the sensors was highly dependent on the calibration type and measurements used for deriving the calibration function. The electrochemical sensor showed high sensitivity by responding to alternating anaerobic/anoxic conditions simulated during nitrate dosing. All sensors were prone to measurement disturbances due to high amounts of sanitary solids in wastewater at the study site and required continuous maintenance for reliable measurements. Finally, a summary of the key attributes and limitations of the sensors compared for liquid phase H2S detection is outlined.

Graphical analysis of multiple inert gas elimination data

1983 ◽  
Vol 55 (1) ◽  
pp. 32-36 ◽  
Author(s):  
W. E. Stewart ◽  
S. M. Mastenbrook
Keyword(s):  
Gas Exchange ◽  
Companion Paper ◽  
Graphical Analysis ◽  
Inert Gases ◽  
Inert Gas ◽  
Additional Test ◽  
Multicompartmental Model ◽  
Simple Rules ◽  
Gas Measurements ◽  
Mixed Venous

A plot of measured retention-excretion ratios [(Ri/Ei)obs] vs. reciprocal solubility (1/lambda i) for selected inert gases allows quick detection of shunt and ventilation-perfusion (V/Q) inhomogeneity in the lung. We derive simple rules for constructing a smooth R/E function from the data, using a multicompartmental model of the lung. If mixed venous inert gas measurements are available, the values [lambda i(1-Ri)/Ei]obs for the infused gases can be used to estimate the overall VT/QT ratio and provide an additional test of the consistency of the data. For any set of equilibrium compartments ventilated and perfused in parallel, we show that d(R/E)/d(1/lambda) cannot be negative, nor can d2(R/E)/d(1/lambda)2 be greater than zero. A rectilinear R/E function implies a narrow distribution of V/Q among the gas exchange compartments, whereas a downward-concave curve implies a broader distribution. The shunt perfusion and dead-space ventilation can be estimated from the asymptotes of the R/E function. The range of V/Q for the gas exchange compartments can also be bracketed if a well-defined region of curvature is present in the graph. Finally, from the R/E vs. 1/lambda graph and (if mixed venous data are available) from the lambda(1-R)/E values, we can determine quickly whether the data deserve the detailed numerical analysis outlined in our companion paper.

Pt coated Cr2O3 thin films for resistive gas sensors

Open Physics ◽  
2009 ◽  
Vol 7 (2) ◽  
Author(s):  
Aarne Kasikov ◽  
Alar Gerst ◽  
Arvo Kikas ◽  
Leonard Matisen ◽  
Agu Saar ◽  
...  
Keyword(s):  
Gas Sensors ◽  
Photoelectron Spectroscopy ◽  
Vacuum Annealing ◽  
High Vacuum ◽  
Atomic Layer ◽  
Electron Beam Evaporation ◽  
X Ray ◽  
Chemical States ◽  
Gas Measurements ◽  
Resistive Gas Sensors

AbstractThe resistive response of atomic layer deposited thin epitaxial α-Cr2O3(0 0 1) films, to H2 and CO in air, was studied. The films were covered with Pt nanoislands formed by electron-beam evaporation of a sub-monolayer amount of the material. The gas measurements were performed at 250°C and 450°C. These temperatures led to different proportion of chemical states, Pt2+ and Pt4+, to which the Pt oxidized. The modification was ascertained by the X-ray photoelectron spectroscopy method. As a result of the modification, the response was fast at 250°C, but slowed at 450°C. A disadvantageous abundance of Pt4+ arising at 450°C in air could be diminished by high-vacuum annealing thus restoring the response properties of the system at 250°C.

scholarly journals An assessment of the climatological representativeness of IAGOS-CARIBIC trace gas measurements using EMAC model simulations

2016 ◽  
Author(s):  
Johannes Eckstein ◽  
Roland Ruhnke ◽  
Andreas Zahn ◽  
Marco Neumaier ◽  
Ole Kirner ◽  
...  
Keyword(s):  
Climate Model ◽  
Trace Gases ◽  
Measurement Data ◽  
Trace Gas ◽  
Statistical Measures ◽  
Kolmogorov Smirnov ◽  
Gas Measurements ◽  
Passenger Aircraft ◽  
Relative Differences ◽  
Smirnov Test

Abstract. Measurement data from the long-term passenger aircraft project IAGOS-CARIBIC is often used to derive trace gas climatologies. We investigate to what extent such derived climatologies can be assumed to be representative for the true state of the atmosphere. Using the chemistry-climate model EMAC we sample the modelled trace gases along CARIBIC flight tracks. Different trace gases are considered and climatologies relative to the mid-latitude tropopause are calculated. Representativeness can now be assessed by comparing the CARIBIC sampled model data to the true climatological model state. Three statistical methods are applied for this purpose: the Kolomogorov-Smirnov test, and scores based on the variability and relative differences. Generally, representativeness is expected to decrease with increasing variability and to increase with the number of available samples. Based on this assumption, we investigate the suitability of the different statistical measures for our problem. The Kolmogorov-Smirnov test seems too strict and does not identify any climatology as representative – not even long lived well observed trace gases. In contrast, the variability based scores pass the general requirements for representativeness formulated above. In addition, even the simplest metric (relative differences) seems applicable for investigating representativeness. Using the relative differences score we investigate the representativeness of a large number of different trace gases. For our final consideration we assume that the EMAC model is a reasonable representation of the real world and that representativeness in the model world can be translated to representativeness for CARIBIC measurements. This assumption is justified by comparing the model variability to the variability of CARIBIC measurements. Finally, we show how the representativeness score can be translated into a number of flights necessary to achieve a certain degree of representativeness.

Computers for data, control and simulation

1988 ◽  
Vol 46 ◽  
pp. 920-921
Author(s):  
David C. Joy
Keyword(s):  
Personal Computers ◽  
Monitoring And Control ◽  
Data Logging ◽  
Data Logger ◽  
Operational Conditions ◽  
Data Control ◽  
The Many ◽  
And Control

Personal computers (PCs) are a powerful resource in the EM Laboratory, both as a means of automating the monitoring and control of microscopes, and as a tool for quantifying the interpretation of data. Not only is a PC more versatile than a piece of dedicated data logging equipment, but it is also substantially cheaper. In this tutorial the practical principles of using a PC for these types of activities will be discussed.The PC can form the basis of a system to measure, display, record and store the many parameters which characterize the operational conditions of the EM. In this mode it is operating as a data logger. The necessary first step is to find a suitable source from which to measure each of the items of interest. It is usually possible to do this without having to make permanent corrections or modifications to the EM.

On-line Tropical Epidemiology -A Case-Study from The Gambia

1987 ◽  
Vol 26 (02) ◽  
pp. 73-76 ◽  
Author(s):  
Kathryn Rowan ◽  
P. Byass ◽  
R. W. Snow
Keyword(s):  
Data Collection ◽  
Field Trial ◽  
Error Rates ◽  
Database Management System ◽  
Bed Nets ◽  
Completion Rates ◽  
On Line ◽  
Access To Data ◽  
Rapid Processing

SummaryThis paper reports on a computerised approach to the management of an epidemiological field trial, which aimed at determining the effects of insecticide-impregnated bed nets on the incidence of malaria in children. The development of a data system satisfying the requirements of the project and its implementation using a database management system are discussed. The advantages of this method of management in terms of rapid processing of and access to data from the study are described, together with the completion rates and error rates observed in data collection.

Application of graphical analysis of taxonomical structure of diatom complexes in identification of critical conditions of the Neopleistocene lakes (on the example of Bibirevo section)

2019 ◽  
pp. 78-87
Author(s):  
Elena V. Bespalova
Keyword(s):  
Lake Sediments ◽  
Critical Points ◽  
Graphical Analysis ◽  
Volga Region ◽  
Critical Conditions ◽  
Ancient Lake ◽  
Diatom Complexes

Ancient lake sediments of Bibirevo section in the Yaroslavl and Kostroma Volga region are studied by means of graphical analysis of taxonomical structure of diatom complexes. This method allowed to record critical points (change of areas of stability) in the development of a Neopleistocene lake during the transition from stage to stage, as well as from phase to phase.

Causes of ecosystem transformations variability in lakes of the european part of Russia and Western Siberia (diatom analysis)

2019 ◽  
pp. 79-82
Author(s):  
Lev V. Razumovsky
Keyword(s):  
Western Siberia ◽  
Graphical Analysis ◽  
European Part ◽  
Analysis Method ◽  
Climatic Region ◽  
Diatom Analysis ◽  
Lake Ecosystems ◽  
Distinctive Features ◽  
European Part Of Russia

On the basis of author's graphical analysis method, the typification of lake ecosystems transformation scenarios depending on the size of lakes was carried out. It was confirmed that the type of transformation depends not only on size of the lake, but also on the landscape and climatic region in which it is located. The distinctive features of lake ecosystems transformation types in the European part of Russia and in Western Siberia were analyzed and compared.

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