The Czech national standard of low gas flow is based on the dynamic gravimetry principle, defining the flow rate as the mass loss of gas from a pressure bottle which is continuously weighed. This ...weighing is performed in ambient atmosphere, which brings two problems. First, the buoyancy corrections are the main and unavoidable source of uncertainty. Second, condensation of the water vapor on the pressure bottle can occur, due to its cooling below dew point at higher flow rates. A weighing carried out in a hermetically closed atmosphere suppresses the problematic buoyancy effects. A weighing in a vacuum does the same, and also eliminates any danger of water condensation. The paper describes the hermetic and vacuum mode modifications together with the relevant uncertainty analyses.
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•Modifications of a CVAAS Hg0 analyzer suitably for conditions with HCl, NO and NH3.•No interference of all the modified components and processes to Hg0 detections.•Consistent Hg0 ...measurements with the certified mercury permeation rate.•Fast response to real-time Hg0 detections even under such harsh conditions.•Stable real-time monitoring of Hg0 in its catalytic oxidation even at low gas flows.
A commercially-available cold-vapor atomic absorption mercury analyzer had many difficulties in monitoring real-time gaseous mercury (Hg0) in its oxidation over a V2O5/TiO2-based catalyst under conditions additionally containing HCl, NO and NH3. Thus we made extensive modifications to the original analyzer so that this is suitable for fast and stable real-time Hg0 detections even at low sample flow rates as well as at the harsh conditions. Our fully modified analyzer gave Hg0 signals very similar to those based upon the factory-certified permeation rate of the mercury permeation tube. Gaseous Hg0 could react, only to a small extent, with HCl over a quartz powder and the measured Hg0 oxidation activity was almost associated with the catalyst depending on concentrations of HCl fed to gas streams with NO and NH3. This study can offer useful solutions to academic and industrial research groups to attempt real-time Hg0 measurements at such chosen conditions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In the present study, an inductively coupled plasma optical emission spectrometer ICPE-9820 with the mini-torch technology that significantly reduces the consumption of plasma gas to 7.0 L min
−1
was ...applied for the multielemental analysis of wine samples. Three sample preparation procedures (microwave digestion in closed vessels, acid digestion in open vessels in a water bath, both with HNO
3
, and 1:10 dilution with deionized water) were compared for the determination of 15 elements in wines. In all wines analyzed, the lowest concentration was obtained for Li (0.06–0.09 mg L
−1
) and the highest for K (475–995 mg L
−1
). The concentration >1 mg L
−1
of B, Fe, and Na was determined in all wines analyzed by the three sample preparation procedures. The average concentrations found for the acid extracts for Al (1.31 mg L
−1
) and Fe (3.40 mg L
−1
) were higher in comparison to results of sample dilution (0.73 and 1.56 mg L
−1
respectively). The recoveries were between 88.2 and 110 %, 65.9 and 106 %, and 62.8 and 109 %, whereas the relative standard deviations (RSDs) varied between 0.04 and 4.62 %, 0.74 and 5.57 %, and 0.70 and 5.80 %, respectively, for the procedure of sample dilution, microwave digestion, and water bath digestion.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In this work, the recently introduced low flow inductively coupled plasma optical emission spectrometry (ICP-OES) with a total argon consumption below 0.7L/min is applied for the first time to the ...field of food analysis. One goal is the investigation of the performance of this low flow plasma compared to a conventional ICP-OES system when non-aqueous samples with a certain matrix are introduced into the system. For this purpose, arsenic is determined in three different kinds of fish samples. In addition several nutrients (K, Na, Mg, Ca) and trace metals (Co, Cu, Mn, Cd, Pb, Zn, Fe, and Ni) are determined in honey samples (acacia) after microwave digestion. The precision of the measurements is characterized by relative standard deviations (RSD) and compared to the corresponding precision values achieved using the conventional Fassel-type torch of the ICP. To prove the accuracy of the low flow ICP-OES method, the obtained data from honey samples are validated by a conventional ICP-OES. For the measurements concerning arsenic in fish, the low flow ICP-OES values are validated by conventional Fassel-type ICP-OES. Furthermore, a certified reference material was investigated with the low gas flow setup. Limits of detection (LOD), according to the 3σ criterion, were determined to be in the low microgram per liter range for all analytes. Recovery rates in the range of 96–106% were observed for the determined trace metal elements. It was proven that the low gas flow ICP-OES leads to results that are comparable with those obtained with the Fassel-type torch for the analysis of food samples.
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•Low gas flow plasma with a total argon consumption of 0.7L/min.•Analysis of microwave digested foods samples with a low gas flow plasma.•First characterization of the low gas flow plasma regarding non-aqueous samples.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Spectroscopic characteristics of a spiral flow inductively coupled plasma (ICP), which could be sustained stably at 9 L min−1 of Ar plasma gas flow rate with 1.5 kW RF forward power, were studied for ...axially viewing ICPOES. The emission intensity profile, excitation temperature and plasma robustness were evaluated, and were similar to those of the standard ICP. The background and emission intensities of elements as well as the excitation behavior for both atom and ion lines were also examined and compared to those of the standard ICP. Since the spectroscopic characteristics of the spiral flow ICP were similar to those of the standard ICP, it could be used as a new low gas flow ICP in axially viewing ICPOES.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
► We measured the N2 and Ar conductance of a 20μm pinhole orifice for flows into vacuum over upstream pressures ranging from 1Pa to 100kPa. ► The measurement uncertainty was less than 0.2% (k=2) for ...upstream pressures greater than 10Pa. ► A difference between the Ar and N2 reduced flow rate was observed for gas rarefaction parameters greater than 10.
A pinhole orifice with a known conductance can be used as a secondary flow standard. Commercially available laser-drilled pinhole orifices with diameters ranging from 1.0μm to 50μm can have molecular-flow conductances ranging from about 0.1μL/s to 200μL/s for N2 at 23°C. Gas flows of 10−11–10−6mol/s can easily be produced by applying an upstream pressure in the range of 1–105Pa. Accurate measurements of the orifice conductance as a function of pressure are required to use the pinhole orifice as a basis of a flowmeter. We use a constant-pressure flowmeter to make accurate measurements of the conductance of a 20μm orifice as a function of pressure for gas flows of Ar and N2 into vacuum. We present results of these conductance measurements for an orifice with a nominal diameter of 20μm. The N2 conductance of this orifice ranged from 30μL/s to 60μL/s over the range of pressures investigated, and was measured with an uncertainty of better than 0.2% (k=2) for upstream pressures greater than 10Pa.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
A new
P
V
T
t
system (pressure–volume–temperature–time system) has been constructed to establish a standard for a gas flow rate of less than 5 mg/min. This system has two unique aspects for the ...calibration of gas flow meters. First, this
P
V
T
t
system can calibrate any type of flow meter by introducing an automatic pressure controller to keep the downstream pressure of a flow meter constant, although most
P
V
T
t
systems can calibrate only flow meters whose output is not influenced by the change of the differential pressure working on them. Secondly, this system does not need a mass correction in the dead volume in most cases, because the difference of the mass of gas in the dead volume between the final condition and the initial condition would be negligibly small as the initial pressure is used as a trigger to stop the measurement. It is presented in this paper that a mass of gas gathered in the constant volume tank (CVT) is the most important parameter on an uncertainty analysis of a
P
V
T
t
system and the uncertainty of a flow rate must be described with the collection time. In this
P
V
T
t
system, a realistic relative standard uncertainty of a flow rate of 0.01 mg/min is 0.21% when the collection time is 40 h and a realistic relative standard uncertainty is 0.0001% at a flow rate of 5 mg/min with the collection time of one hour.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
9.
Low flow corrosion resistant ultrasonic flow sensor Shinde, Akshay; Agashe, Sudhir; Satpute, Suresh ...
2018 3rd IEEE International Conference on Recent Trends in Electronics, Information & Communication Technology (RTEICT)
Conference Proceeding
This paper describes a novel ultrasonic technique which can be used to measure the volumetric flowrate of industrial gases like H2s, Hci, Nh3, NOx, SO 2 , Cl 2 etc. which are highly corrosive in ...nature. This technique is specifically designed to measure very low flowrates of the above-mentioned gases in an industrial environment. Typical gas flowmeters are susceptible to corrosion in the presence of reactive materials and thus require frequent maintenance or even replacement at times. The measurement technique presented in this paper takes care of the corrosion aspect to a certain extent without affecting its own performance at low flow rates.
Whether a critical orifice with a diffuser worked well as a superior flow meter for low gas flow measurement were examined experimentally. The results show that their discharge coefficients is not ...almost affected by influences of a boundary layer, and their critical pressure ratios are larger than those of ISO type nozzles in the Reynolds number range of less than 900. Furthermore, a sonic plane appearing in a contraction of a jet flow is stable due to an existence of a diffuser wall even when the Reynolds number changes. It is found from these results that a critical orifice with a diffuser, if an orifice diameter is less than 20μm, is applicable to gas flow measurement of lower than 1 mg/min where can not be measured by ISO type critical nozzles.
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