Characterization of Commercially Available Active-Type Radon–Thoron Monitors at Different Sampling Flow Rates

Recently, some commercially available active-type radon–thoron monitors were developed; however, their performance has not been characterized. This article presents the characteristics of three commercially available active-type radon–thoron monitors (RAD7, Radon Mapper, and AlphaGUARD) at different sampling flow rates. The thoron concentration measured by the monitors was compared with the reference value measured by a grab sampling method. As a result, the ratio of the measured concentration to the reference increased with flow rate for the RAD7 and the Radon Mapper although that of the AlphaGUARD decreased. The difference may be attributed to the coefficients used in the calculation and the measurement time scheme. The results indicate the importance of the sampling flow rate in thoron measurement. Monitoring of flow rate at the measurement and periodic calibration at multiple sampling flow rates should be conducted for quality assurance and quality control of the measurand.

Ozone removal efficiency of the KI-denuder in the carbonyl sampling

In the carbonyl sampling of 2, 4- dinitrophenylhydrazine (DNPH) impregnated cartridge, the ozone removal was necessary because ozone reacted with the DNPH derivatives. A commercial ozone scrubber was usually used to remove O3. However, high humidity leaded to carbonyl compounds being trapped on the ozone scrubber before passing through the DNPH cartridge. The purpose of this study was to assess the ozone removal by KI-denuder under the climatic conditions of Ho Chi Minh City. Several parameters including air sampling flow rate and denuder length were optimized to achieve the highest removal efficiency. The optimum parameters of the KI denuder were the sampling flow rate of less than 1 L/min, and the denuder length of 20 cm. The effect of the initial O3 concentration on the removal efficiency was also investigated. Finally, the ozone removal efficiency of KI-denuder was compared to that of ozone scrubber when two devices were applied for the carbonyl sampling during field measurement. The results show that KI-denuder could be used to replace the ozone scrubber with high removal efficiency, particularly in high humidity condition. In conclusion, KI-denuder was effective, simple, easy to use and cheap. Therefore, it was encouraged to use in carbonyl sampling.

Mass change tracking approach as collection guidelines for aerosol and vapor samples released during e-cigarette smoking

There are growing concerns about the lack of a methodological basis for the quantification of various pollutants from electronic cigarettes (ECs). In this study we use a mass change tracking (MCT) approach to explore the potent roles of key sampling variables in the quantitation of EC-produced aerosols/vapors: the sampling flow rate (or puff velocity), battery charge condition, and solution composition.

Correcting aethalometer black carbon data for measurement artifacts by using inter-comparison methodology based on two different light attenuation increasing rates

In black carbon (BC) measurements obtained using the filter-based optical technique, artifacts are a major problem. Recently, it has become possible to correct these artifacts to a certain extent by using numerical methods. Nevertheless, all correction schemes have their advantages and disadvantages under field conditions. In this study, a new correction model that can be used for determining artifact effects on BC measurements was proposed; the model is based on two different light attenuation (ATN) increasing rates. Two aethalometers were used to measure ATN values in parallel at aerosol sampling flow rates of 6 and 2 L min−1. In the absence of sampling artifacts, the ratio of ATN values measured by the two aethalometers should be equal to the ratio of the sampling flow rates (or aerosol deposition rates) of these two aethalometers. In practice, the ratio of ATN values measured by the two aethalometers was not the same as the ratio of the sampling flow rates of the aethalometers because the aerosol loading effects varied with the aerosol deposition rate. If the true ATN value can be found, then BC measurements can be corrected for artifacts by using the true ATN change rate. Therefore, determining the true ATN value was the primary objective of this study. The proposed correction algorithm can be used to obtain the true ATN value from ATN values acquired at different sampling flow rates, and the actual BC mass concentrations can be determined from the true ATN change rate. Before BC correction, the BC concentration measured at the sampling flow rate of 6 L min−1 was smaller than that measured at 2 L min−1 by approximately 13 and 9% in summer and winter seasons, respectively. After BC correction by using the true ATN value, the corrected BC for 6 L min−1 can be exactly equal to the corrected BC for 2 L min−1. Field test results demonstrated that loading effects on BC measurements could be corrected accurately by using the proposed model. Additionally, the problem of enhanced light ATN caused by light scattering at the unloaded filter can be overcome without using any light scattering coefficient. Therefore, the correction algorithm can be applied to a newly designed instrument to determine actual real-time BC concentrations by using two sampling spots for different aerosol deposition rates. Moreover, a simple empirical correction scheme for post-processing for correcting the existed aethalometer BC data is also presented. While this simple correction scheme is dependent on the aerosol type, it can be used to correct BC data when the primary source of BC and the weather conditions are similar to those in this study. Furthermore, two existed aethalometers with appropriate flow control can be used to create correction schemes suitable for different environments.

Sampling Flow Channel Design in Automobile Engine Intake Manifold

As a result of turbulence and wide flow velocity range, flow velocity in engine intake manifold cannot be tested directly by using a thermal flow sensor. In this study, a sampling flow channel is designed according to the testing conditions and range of the thermal flow sensor. The flow velocity in the whole intake manifold was simulated by the finite element method software program. was found proportional to , and slope K was constant. ranged from 0 m/s to 4.8 m/s at the suitable outlet position of the sampling flow channel, which could be tested for the thermal flow sensor. The mass flow intake manifold was obtained by testing the mean flow velocity in the test section of the sampling flow channel .

The Fuzzy-PID Algorithm Apply to the Constant Gas Flow Control of the Dust Sampler

The Sampling flow will be decreased because the permeability weakness of filterable membrane after the dust sampler working for a period of time. It seriously affects the accuracy of measurement, so we should keep the dust sampler working under the constant gas flow. The stable, rapidness and accuracy constant sampling can be achieved based on the application of fuzzy-PID algorithm and the adoption of PWM technique. It has carried on design to the dust sampler control system from selecting the hardware and designing the software to data processing and errors analysis, and discussing the preferable performance of the dust sample control system.