Fume Hood Research Articles

Investigation on improving fume hood performance via elimination of internal vortices: Experiments and CFD

The design elements of a fume hood and the synergy between them are essential for a fume hood to be used for containment in a chemical laboratory. A computational fluid dynamic simulation with an orthogonal design was validated and executed to determine the aerodynamic characteristics of the fume hood. The ventilation efficiency, that is, the ratio of tracer gas concentration in the exhaust outlet to the hood chamber was introduced as an indicator to evaluate fume hood performance. The ventilation efficiency was found to vary between 4.7 and 12.9 with different baffle opening ratios. The designed doorsill could effectively inhibit the separation of the air boundary layer and thus avoids vortex generation behind the doorsill. The auxiliary air supply would eliminate the eddies behind the sash and could further increase the ventilation efficiency to 13.9. All the designed elements above jointly contribute to the absence of vortices in the flow pattern that is within the hood chamber. The airflow would move from top to bottom and from outside to inside, which would minimize the spread of pollutants to the breathing zone. This paper is intended to contribute to the optimization of the aerodynamic design of fume hoods in chemical laboratories.

Rapid Robot-Aided On-site Testing of Fume Cupboards.

Although containment testing of fume cupboards (FC) according to the standards EN 14175-3 (2019) or ANSI/ASHRAE 110 (2016) is well established for type testing, its application is currently much less accepted and practised for evaluating containment on-site. Few of the several million FC in the market have been tested at installation and commissioning, and even less undergo verification of containment during their service life in the laboratories. Several reasons have led to this unsafe situation. To address this challenge, a new concept has been developed to allow for rapid on-site testing of FC to gain knowledge as to the functional efficiency as well as to safety aspects for the operator. The concept consists of a movable robot-aided test equipment that can be installed quickly to the FC in running labs. Multiple sensors detect the tracer gas isopropanol. Within a test run of only 10-min data is collected to quantify containment at the sash opening and to determine purge efficiency. The method reveals impact from interfering effects such as draughts, air distribution, and movements and from equipment installed, and is a tool for the optimization of operating conditions of a lab. This article presents an advanced alternative to the existing containment tests, particularly for on-site testing. The method assesses not only proper operation of the FC in its environment, but also the suitability of a FC for a given use under aspects of health and safety evaluation.

Emission characteristics of formaldehyde from natural gas combustion and effects of hood exhaust in Chinese kitchens

Formaldehyde (HCHO) is a well known carcinogen. While most studies investigate emission from wood-based materials, knowledge about releasing of HCHO by natural gas combustion is quite limited. This study conducted field measurements in 9 households to address this issue. We found that emission factor is mainly in the range of 50–200 mg_HCHO/m3_natural gas (median value is 85 mg/m3). Emission rate mainly falls into a range of 0.1–0.4 mg_HCHO/min (median value is 0.16 mg/min). It is also revealed that as the natural gas flow rate increases, the emission factor decreases with a statistically significant Spearman correlation coefficient of −0.46 (p < 0.05). The emission rate shows an opposite trend with a Spearman correlation coefficient of 0.48 (p < 0.05). Formaldehyde generated by natural gas combustion in kitchens can quickly disperse to an adjacent living room when kitchen door is open. A range hood can effectively remove formaldehyde in kitchens if kitchen window is open and kitchen door is closed. Its performance would decrease by half otherwise. These results imply a health co-benefit of reducing household usage of carbon-based natural gas in the age of carbon neutrality aiming climate change.

Front Cover: Online monitoring of small volume reactions using compact liquid chromatography instrumentation

DOI: 10.1002/sscp.202200012 The cover picture represents the translation of repetitive reaction mixture analysis outside a fume hood using a conventional high performance liquid chromatography stack with manual syringe sampling to online analysis inside a fume hood using a simple, compact, hand-portable capillary liquid chromatograph that can be easily placed very close to the reaction vessel. The extremely small sample volume required for analysis by capillary liquid chromatography allows the use of miniature reaction vessels with minimal disturbance of the reaction mixture.

Marcin Lindner

"I chose chemistry as a career because you can create and obtain many things, which are perhaps, at this specific moment, prepared only at your own fume hood … I am waiting for the day when someone will discover the tool which would help to make every day a way longer …" Find out more about Marcin Lindner in his Introducing … Profile.

Lab-Scale Cultivation of Cupriavidus necator on Explosive Gas Mixtures: Carbon Dioxide Fixation into Polyhydroxybutyrate.

Aerobic, hydrogen oxidizing bacteria are capable of efficient, non-phototrophic CO2 assimilation, using H2 as a reducing agent. The presence of explosive gas mixtures requires strict safety measures for bioreactor and process design. Here, we report a simplified, reproducible, and safe cultivation method to produce Cupriavidus necator H16 on a gram scale. Conditions for long-term strain maintenance and mineral media composition were optimized. Cultivations on the gaseous substrates H2, O2, and CO2 were accomplished in an explosion-proof bioreactor situated in a strong, grounded fume hood. Cells grew under O2 control and H2 and CO2 excess. The starting gas mixture was H2:CO2:O2 in a ratio of 85:10:2 (partial pressure of O2 0.02 atm). Dissolved oxygen was measured online and was kept below 1.6 mg/L by a stepwise increase of the O2 supply. Use of gas compositions within the explosion limits of oxyhydrogen facilitated production of 13.1 ± 0.4 g/L total biomass (gram cell dry mass) with a content of 79 ± 2% poly-(R)-3-hydroxybutyrate in a simple cultivation set-up with dissolved oxygen as the single controlled parameter. Approximately 98% of the obtained PHB was formed from CO2.

Radiological HEPA Filter 10-year Lifetime Evaluation in Research Facilities.

High-efficiency particulate air (HEPA) filters are widely employed by nuclear facilities to remove radiological particulate matter from their effluent exhaust streams. The purpose of this study is to evaluate the relationships between the 10-y HEPA filter lifetime deployment and its other performance indicators. This 10-y-long endeavor to collect and analyze data regarding the service life of HEPA filters at the Pacific Northwest National Laboratory began in 2010. A set of HEPA filters was selected, and the filters have been surveyed and analyzed at least annually to verify compliance with permit conditions. The study suggests the frequency of filter replacement should be based on the actual operational requirements, such as fume hood face velocity and/or efficiency test results, instead of on the prescribed filter "age limit" of 10 y from the date of manufacture (e.g., birth date) when operating under dry conditions. The study has now been completed, and over the past decade, all the HEPA filters have been replaced due to either technical issues as listed in this report or the previously recommended filter "age limit" of 10 y as prescribed by the oversight bodies. Experimentally determined failure rates are also determined from the data set and can be used to estimate the chances of HEPA filters surviving 15, 20, or even 30 y.

Development of a bench-scale apparatus to assess thermal protective performance of garments under highly intensive heat-flux exposures

Thermal protective clothing protects emergency responders from fire hazards. The thermal protective performance of the multi-layer fabric is standardly evaluated at the average value of a 1–3-cal/(cm2s)-intensity range. Considering the magnitude of modern fire events, the range’s upper limit (3 cal/(cm2s)) was proposed to take into account a critical radiation condition and a bench-scale apparatus, capable of creating the critical experimental environment, was developed in this study. This instrument includes a vertical configuration heater with an active water-cooling part, a vertical orientation specimen-assembly with a measuring part, a movable specimen-holder and thermal shields operated by pneumatic pumps, an exhaust hood connected to a pan, a data acquisition system, heating-power and mechanical equipment controllers and a computer with in-house burn-injury analysis software. A preliminary test was conducted to determine a specimen-assembly position that both optimised the heat-source power, heater-capability and apparatus-sustainability, and subsequently validated the uniformity and consistency of irradiance on the test sample. To conduct repeatable measurements, an in-house program was used to operate the heater, specimen assembly and thermal shields semi-automatically, in a sequence. The software includes an algorithm that allows one to analyse heat transfers across human-skin layers and to assess the degree of burn injuries. This paper outlines a comprehensive process of creating an experimental environment for samples that need to be exposed to a critical thermal condition.

A study on the pollutant control effect of a new push-pull exhaust hood under different pollutant velocities

The double-side single-slit symmetrical push-pull grooved exhaust hood (DSPGEH) has better pollutant control performance than the traditional push-pull groove-side exhaust hood (TPGEH), and the airflow of DSPGEH is easily disturbed by the non-polluting airflow in the middle part of the industrial slot, resulting in gaps when the airflow is blocked, and thus pollutant escape occurs. In this study, different air blowing speed and pollutant emitting speed of DSPGEH are investigated. The double-side double-slit symmetrical push-pull grooved exhaust hood (DDPGEH) was proposed and its effect of pollutant sealing and energy saving was investigated. The results show that the mixed airflow used in the DDPGEH air supply airflow can effectively seal the pollutants in the working area of the exhaust hood. Compared with TPGEH, the energy saving rate of DSPGEH is 80.23% and that of DDPGEH is 96.70%. This study provides a new reference standard for the operation parameters of push-pull exhaust hoods and new ideas for the optimization of push-pull exhaust hoods.

Experimental and numerical simulations of human movement effect on the capture efficiency of a local exhaust ventilation system

In local exhaust ventilation systems, external turbulence from e.g. human movements can affect the capture efficiency of the system considerably. In this study, experimental and numerical (CFD) approaches were utilized to evaluate the effect of human movement on the capture efficiency of a local exhaust ventilation system with an exterior circular hood. Human movements were simulated by back-and-forth movements of three human-sized moving objects: a flat plate (CFD + experimental), a cylinder (CFD) and a human-shaped manikin (CFD), respectively. The experiments consisted of tracer gas measurements in a full-scale test room. The numerical simulations included dynamic mesh methods to handle object movements. The results showed reasonable agreement between numerical and experimental results regarding the capture efficiency at different movement frequencies and exhaust flow rates, indicating that CFD is a feasible method for investigating complex flows of the studied kind. In comparison with the moving manikin, the moving plate caused significantly lower capture efficiency, whereas the moving cylinder yielded higher values. Overall, the results with the cylinder as moving object proved more similar to those of the manikin than the results with the flat plate. These findings have particular relevance towards existing test standards that stipulate the use of a moving flat plate in similar test situations. Further, some parameter variations verified that local exhaust capture efficiency increases by increasing the exhaust air flow rate and movement time interval, and also by decreasing the distance between contaminant source and exhaust hood opening. Also increasing the distance between the movable object and the contaminant source, as well as decreasing the diameter of the exhaust hood opening increased the capture efficiency.

The effect of the body wake and operator motion on the containment of nanometer-scale airborne substances using a conventional fume hood and specially designed enclosing hood: a comparison using computational fluid dynamics

The effect of the body wake and operator motion on the containment of nanometer-scale airborne substances using a conventional fume hood and specially designed enclosing hood: a comparison using computational fluid dynamics

The Chemistry Teaching Laboratory: A Sensory Overload Vortex for Students and Instructors?

Engaging in laboratory practical activities, developing laboratory practical skills, and, to a degree, even wearing laboratory protective equipment such as safety coats and goggles are all quintessential components of chemistry education. It is becoming quite common for institutions to invest in large-scale chemistry teaching laboratories, filling them with cutting-edge technology, chemicals and apparatus, digital learning tools and laboratory furniture. It is also becoming quite common for educators to develop and execute well considered, research-based approaches to learning and teaching in the laboratory. However, despite such grand and admirable commitments and ambitions, there seems to be little acknowledgment of just how difficult it can be for some to be a room that is so noisy, bright, odorous and surrounded by hazards, risks, chemicals, glassware, electricity, gas, naked flames, eye washes, body showers, fume hoods─the list goes on. While sensory overload issues were once associated with psychiatric mental disorders such as Autism, Schizophrenia, and Attention Deficit Hyperactivity Disorder, it is now becoming known that anyone, regardless of whether they have a psychiatric mental disorder, can experience sensory issues for a variety of reasons. As such, while the chemistry teaching laboratory and all its sense-demanding intricacies might be manageable for some, for other students and instructors akin who experience sensory overload issues, it can be a most-unnerving environment to be in, let alone to think about chemical concepts. The purpose of this Article is to review literature on the concept of sensory overload, consider some research on sensory overload, and identify how this may implicate chemistry laboratory education.

Removal Efficiency of PM10 via Ventilation with Residential Exhaust Hood and Conditions for Reducing Human Intake Fraction

Removal Efficiency of PM10 via Ventilation with Residential Exhaust Hood and Conditions for Reducing Human Intake Fraction

Quantitative evaluation of chemical fume hoods performance by CO2 tracer gas.

Various chemical substances and carcinogens have been presented in medical sciences universities' educational and research laboratories. For this purpose a suitable ventilation system had to be implemented to ensure the correct operation of the hoods. To evaluate the performance of laboratory chemical fume hoods of the University of Medical Sciences using a novel quantitative method. In this study, 43 chemical fume hoods were investigated in the laboratories of the University of Medical Sciences. The technical specifications of the hoods and their compliance with the standard have been investigated. The hoods face velocity was measured using a thermal anemometer. Quantitative evaluation was performed using the new method of CO2 tracer gas and the results were analyzed using SPSS software version 19. The hoods presented both favorable and unfavorable results in terms of technical specifications and location. The results showed 50.2% of the hoods have visible leakage. Hood face velocity was not suitable for any of the hoods in the case fully open.when half open only 16.3% of the hoods and in the case of 25% open face, 34.9% of the hoods had a good velocity. Most hoods have CO2 leakage even at small amounts. the unsuitable performance of the hoods is mainly due to the unsuitability of the fans, furthermore investigation and correction of technical problems are required. The new quantitative method is a suitable method for routine evaluating chemical fume hoods and can replace the SF6 gas tracer method.

Research on a push-pull industrial trough-side exhaust hood based on CFD simulation and experiment

The traditional industrial trough-side exhaust hood requires large energy consumption for one-way airflow because the air inlet and outlet are on both sides of the industrial slot. In this research, based on the improvement of the traditional push-pull trough-side exhaust hood, a double-sided symmetrical push-pull industrial trough-side exhaust hood is researched. Simulation software ICEM and FLUENT were used to research the relationship between the distance of air inlet and outlet and the air volume ratio, and the relationship between the air volume ratio and mass fraction of pollutant gases, using carbon monoxide as the pollutant gas. The research found that when the pollutant mass fraction reaches the specified level, the air inlet and outlet distance is quadratically related to the air volume ratio. When the distance between the inlet and outlet is 0.12 m and the corresponding minimum flow ratio is 1.7, the interference of the suction air outlet pressure on the blowing air outlet jet reaches the minimum. By comparing the energy consumption with the traditional industrial trough-side exhaust hood, the energy saving rate is 75.8% with the same pollutant control effect. The double-sided symmetrical push-pull industrial trough-side exhaust hood reduce the cost of treating and discharging pollutants and provides a new idea for industrial pollutant treatment.

Changing Patterns of the Flow Ratio with the Distance of Exhaust and Supply Hood in a Parallel Square Push-Pull Ventilation.

The method of flow ratio k is often used for designing parallel push-pull ventilation. The k value is mostly selected empirically and is difficult to determine accurately, resulting in an imprecise design of the push-pull ventilation system. Therefore, parallel push-pull ventilation was taken as the research object in this paper. The push-pull ventilation studied consists of a square uniform supply hood and a square uniform exhaust hood, and the side length of pull hood and pull hood was same. A workbench was set between the push hood and pull hood, and the source of toluene pollutions was set in the center of the worktable surface. The optimal k values for different distances between push hood and pull hood were studied by numerical simulation using Ansys Fluent, which were obtained base on the distribution of wind speed and toluene concentration. The results showed that parallel push-pull ventilation is not suitable for applications when L/a ≥ 6. The changing patterns of k value with L/a is proposed in the range of 1.5 ≤ L/a ≤ 5 for the parallel square push-pull ventilation, which can be used to estimate k value relatively accurately under the condition that L/a is known, so as to guide the determination of the exhaust air volume of the parallel push-pull ventilation system.

Reducing environmental impacts of marine biotoxin monitoring: A laboratory report

Laboratories globally contribute significantly to consumption of resources, greenhouse gas emissions, and generation of waste. Shellfish destined for human consumption are required to be tested for the presence of regulated marine biotoxins, that can be harmful to human health. Whilst running the national monitoring program for the detection of biotoxins in shellfish, efforts were made to increase resource efficiencies by reducing waste and energy consumption leading to reduced environmental and financial costs. Methods were verified to allow transitions to more sustainable and environmentally-friendly consumables, replacing plastics with paperboard and glass alternatives, leading to a reduction in the consumption of single-use plastics by 69%. A shift to polystyrene recycling and composting non-toxic shellfish waste led to an overall reduction in non-chemical waste of &gt;95%. Adoption of green analytical chemistry principles to procurement and preparation of chemical solutions led to a reduction in hazardous chemical waste by ~23%. A further reduction in printing (~81%) was achieved by transitioning to digital document control. Strategies to reduce energy consumption through ‘switch off’ campaigns and improved fume hood and cold storage equipment management were also implemented. Fume hood and cold storage equipment energy consumption was reduced by 30%. The strategies implemented could be adopted by other laboratories e.g., monitoring and research laboratories dealing with pharmaceutical, biological, and environmental samples.

Energy-guzzling fume hoods put on a diet

Energy-guzzling fume hoods put on a diet

Energy-guzzling fume hoods put on a diet

Energy-guzzling fume hoods put on a diet

Chemical fingerprinting and characterization of spilled oils and burnt soot particles – A case study on the Sanchi oil tanker collision in the East China Sea

The condensate spill accident from the Sanchi oil tanker collision in the East China Sea is unique in world history. To date, the spilled and burnt amounts of condensate remain unknown. The present study demonstrates the chemical fingerprints of a surrogate condensate (SC) from the same source, and of the carried heavy fuel oil (HFO) of the Sanchi accident. The evaporative features of the condensate are demonstrated by allowing the SC to naturally volatilize in a dark fume hood. In addition, the combustion emission of the SC is characterized by conducting a laboratory-scale combustion experiment. The evaporation experiment suggests that the volatilization process plays a significant role in the weathering of the condensate. The results show that the SC and HFO can be clearly distinguished based on their chemical fingerprints of C27–C35 hopanes and C9–C36 n-alkanes, along with priority polycyclic aromatic hydrocarbons (PAHs) and their alkylated derivatives. The compositional data reveal that the lighter component is predominant in the SC, thereby supporting its high volatility and flammability. The greater amounts of heavier components in the HFO indicate its long-term degradation and potential ecological risks to the environment. Further, the trisnorhopane thermal indicator (Ts/Tm) and C29/C30 ratio of hopanes are validated for identification of the SC and the HFO. More importantly, the changes in the hopane ratios of the soot particles are analyzed for the first time in this study, and the results demonstrate the validity of using hopane ratios to fingerprint the condensate soot particles. The diagnostic ratios of 2-MP/1-MP, 9/4-MP/1-MP, and InP/(InP+BghiP) also show decent performance on source identification after the condensate evaporation and combustion processes.