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Metalworking fluids are used in many industries, especially those with metalworking processes. Despite their widespread use, these compounds have harmful effects on human health. Therefore, this study aimed to assess the semi-quantitative health risks of oil mists in the automotive industry. In this study, ACGIH, IARC indexes, LD50, and the risk of corrosion were used to determine the hazard rate, with the biggest index serving as the hazard rate's base. The actual exposure level was used to compute the exposure rate. Sampling and determination of oil mists were performed according to NIOSH 5026 method and using a membrane filter (37-mm). All risk rates of oil mists were in the high-risk range (H). The hazard rate level for all oil mists was equal to 4. The exposure rate for all oil mists except one of them was equal to 4. Considering the health risks identified in this study, it can be concluded that lathe workers in the automotive industries have a high risk in terms of metalworking fluids exposure. [ABSTRACT FROM AUTHOR]

Oil mist coalescence and filtering are extensively used in the fields of natural gas purification and chemical production. However, it remains technically challenging to capture high-concentration, small-sized, oil mist droplets under complex industrial field conditions. To solve this problem, three novel high-efficiency coalescence filter cartridges are proposed, which have improved filter material arrangements. The filtering performance of the cartridges was evaluated in the laboratory and at a natural gas pipeline pressure station under different working conditions to understand the mechanism by which high-concentration small-sized droplets are captured. According to the laboratory results, the filtration efficiency for droplets> 0.2 µm can reach 99.99% if the first layer in the cartridge has a small pore size (1.5 µm). The use of a filtering material with a large pore size can reduce the pressure drop. An arrangement of layers with increasing pore sizes can significantly improve the quality factor of the cartridges and decrease secondary entrainment. In the field test, the size distributions of the oil mist under compressor "hot standby" and operating conditions were gained for the first time. The median size of oil mist droplets was 1.2 µm during hot standby and 0.5 µm during operation. Under both compressor modes, the downstream oil mist concentrations of the proposed cartridges were> 95% lower than that of an existing commercial cartridge once filtering reached a steady state. In a long-cycle test under field conditions, the proposed cartridges showed more stable filtering performance than the existing product, with the filtration efficiency being about 40% higher after 15 days. Moreover, the oil mist coalescence mechanism was determined by microscopic characterization of liquid channels. • An improved filter cartridge for oil mist separators was proposed. • An arrangement of layers with increasing pore sizes can significantly improve the quality factor and decrease secondary entrainment. • The proposed cartridges showed more stable filtering performance than the existing product. • The oil mist coalescence mechanism was determined by microscopic characterization of liquid channels. [ABSTRACT FROM AUTHOR]

Oil mist adversely affects the health of workplace workers, and for this reason, regulations on the limitation of the oil-mist exposure of workers are becoming stricter. In order to reduce the amount of the exposure of workers to oil mist, it is important to effectively remove oil mist from machine tools. In this study, the collection efficiency according to the geometry of the oil-mist-collection cyclone consisting of several disks and the output power and rotation speed of the motor were evaluated. Most of the generated oil mists were less than 10 μm, and the mist removal was assessed using an optical particle counter. The cyclone airflow rate increased linearly with the rotational speed, and the rate was affected more by the cyclone geometry than by the power consumption. The mist-removal performance was significantly enhanced when plate- and cone-type disks were added to the rotating blades. The removal efficiencies of PM10 and PM2.5 under the maximum operational conditions of 5000 rpm and a flow rate of 3.73 m3/min were 93.4% and 78.4%, respectively. The removal capacity was more affected by the cyclone geometry than the rotational speed. The experimental results were similar to those predicted by the modified Lapple theory when an appropriate slope parameter (β) was used. [ABSTRACT FROM AUTHOR]

The electrostatic precipitator (ESP) is widely used in the purification of oil mist particles in the industrial workshops. Different from the solid particles, the deposition of oil mist particles in the ESP can reach a steady state and form a saturated oil film on the electrode plate. Based on the deposition experiment data, this paper has established the oil film flow model in ESP coupled with the corona discharge, the gas flow and the oil mist particle deposition model. The characteristics of oil mist particles deposition and the oil film flow were studied. The results show that the oil film is thin in the electrode plate where the current density is high. The oil film is thick at the inlet of ESP and the corresponding collection plate in the middle of the adjacent electrode wires. The peak value appears at the corresponding plate in the middle of the first two electrode wires, which is more than 50 µm. The average oil film thickness is about 9 µm in the current study. As the inlet velocity increases or the applied voltage decreases, the oil film distribution becomes more uniform, and the oil holding capacity of the electrode plate increases. [ABSTRACT FROM AUTHOR]

A large number of metalworking fluids in industrial manufacturing processes generate high-concentrations of oil mist pollution, which is a typical semi-volatile aerosol and is generally composed of liquid particles and volatile gas components. Long-term exposure to oil mist pollution brings a series of occupational diseases to workers. For the semi-volatile aerosol, the traditional filter sampling method will lead to particle volatilization, which underestimates the concentration of particles and overestimates the concentration of gas. Therefore, this study combined the advantages of the electrostatic method and the Tenax tube adsorption method, to develop a more accurate measurement technology. First, a dichotomous sampler that could efficiently separate the gas and liquid phases of aerosols was optimized through a numerical model, which was validated by literature results. Next, a test table for oil mist sampling was built with a sampler which was fabricated by 3D printing, and the performance of the sampler was evaluated. The results show that the sampling technique can separate the gas and particulate phases of the oil mist efficiently and accurately. Compared with the traditional single sampling methods, the new sampler can better determine the true concentration of oil mist. [ABSTRACT FROM AUTHOR]

• Increase of treated area ratio leads to a variation on the wettability from oleophilic to oleophobic. • Treated filter medium under the optimal spraying time has the highest quality factor. • Optimal spraying time varies with filter media due to different structures. • Quality factors of dual-layer filters with overlapped strips are higher than those with staggered ones. Fibrous coalescence filters are widely used to remove oil mists from air and gas streams in industrial applications. The wettability of filter media significantly affects the filtration performance. Although some efforts have been made to improve the filtration performance based on the modification of filter media wettability by surface treatment method, of which the influence on liquid transport mechanism in the filters and the filtration performance is still needed to elucidate. In this paper, oleophilic filter media were treated by fluorocarbon copolymer solution using a spraying method. The effects of the treated area ratio, spraying time and combinations of patterned filter media on the filtration performance were investigated experimentally. The results show that the increase of the treated area ratio contributes to a variation on the wettability from oleophilic to oleophobic, resulting in a decrease in the jump pressure drop and an increase in the filtration efficiency. The treated filter medium under the optimal spraying time has the highest quality factor, which is 2 ∼ 3 times the untreated one. For the dual-layer patterned filters with alternative oleophobic and oleophilic strips, when the number of oleophobic strips patterned in the first layer filter medium is the same, the pressure drop and filtration efficiency of the overlapped arrangement are lower than those of the staggered arrangement. In all configurations, the highest quality factor is found in the dual-layer filter with the overlapped arrangement and four oleophobic strips patterned in the first layer, resulting from the lowest steady pressure drop and relatively high filtration efficiency. [ABSTRACT FROM AUTHOR]

• Contact angle and surface tension of oil/refrigerant mixture were measured. • The contact angle of the PAG/CO 2 mixture decreased with refrigerant concentration. • PAG and PAG/CO 2 mixture showed complete wetting on metal plates. • The wetting progressed according to Tanner's law. Separation of oil from refrigerant is important to reduce the oil circulation rate in a refrigeration cycle. Since the oil separation depends on the droplet size of oil mist in a compressor and the condition of the oil film on the inner surface of the compressor shell, this study examined the wettability of a metal surface with the oil/refrigerant mixture and surface tension. The wettability of metal surfaces with PAG/CO 2 mixture was evaluated by measuring the contact angle of droplets on the metal surface. The surface tension of the mixture was measured using a pendant drop method. It was found that the wetting of the metal surface with the oil/refrigerant mixture showed a complete wetting, and the contact angle decreased with the refrigerant concentration. Taking the Ohnesorge number into account, the initial spreading of oil mist on the metal surface under discharge conditions should immediately become a viscus-dominant condition. [ABSTRACT FROM AUTHOR]

• Slow increase of Δp (creep) during steady state is caused by accumulation of oil. • Creep is most pronounced for highly efficient filter media. • Different steady states for pre-saturated and initially dry filters. • Temporarily reduced air flows might result in pre-saturated steady states. This paper addresses the phenomenon of a slow Δ p increase ("creep") sometimes observed in mist filters during their so-called steady-state operation, especially at relatively high flow rates and aerosol loads (Kolb et al., 2017). This creep phenomenon draws into question the concept of steady state and awaits a physical explanation on the basis of more systematic data. The present study was performed with conventional glass microfiber filter media at filter face velocities in the range of 1–70 cm/s, using submicron oil aerosol at loading rates up to 1.1 g/(m2 s). Experiments started either with a dry filter (designated as S 0 = 0, where S stands for the liquid saturation level), or with a completely pre-saturated filter (designated as S 0 = 1). The S 0 = 0 runs reached "steady state" (defined here as the onset of drainage) after approximately 0.3 h and were then loaded continually for another 100 h. Runs starting at S 0 = 1 reached a steady state very quickly. With regard to Δ p, all filters featured Δ p creep when starting from S 0 = 0. For coarse filter grades, Δ p creep effectively ended in less than 40 h at moderate flow velocities; finer grades crept further and did not stop creeping within any reasonable loading time. When starting from S 0 = 1, a steady Δ p endpoint was reached rapidly, but was considerably higher than the level attained by creep. It was further shown that creep is associated with a slow increase in the saturation level and that S approached the (higher) level of pre-saturated filters. The increase in S during creep was associated with the formation of additional fine oil channels. Conversely, oil channels were completely absent in pre-saturated filters and the liquid was uniformly dispersed. Using simple theoretical considerations for flow in porous media, the observed differences in Δ p are explained in part by the difference in S between S 0 = 0 and S 0 = 1 filters, and in additionally also by taking into account the different liquid distribution patterns. We conclude that the onset of drainage under steady external conditions – the stage conventionally viewed as the beginning of steady-state operation – does not automatically represent an internal steady state with regard to saturation levels or pressure drop; and presumably also not for the oil distribution pattern. The internal saturation reaches a stable endpoint sooner than the pressure drop, which may continue to creep for the lifetime of the filter. Of and when a transition from channel patterns to homogeneous oil distribution occurs during steady operation is not known. However, the transition can be forced rather quickly by operating the filter intermittently at a very low flow velocity. [ABSTRACT FROM AUTHOR]

Building on work by Kampa et al. (2014) about the liquid distribution in multi-layer oil mist filters, a mesoscale empirical model is proposed for their efficiency. It decomposes the total penetration into a product of independent ‘building blocks’ that are aligned with the mesoscale liquid distribution in steady state, essentially in the form of an oil film and a channel region. The film (typically one very thin region per sandwich) is associated with a film penetration P film and the channel region (consisting typically of multiple layers) with a channel penetration P channe l . The first layer of wettable media also represents a separate contribution P 1st layer . A method is described to derive these unit penetrations from a set of measurements. Experiments are then carried out with filters composed of conventional glass microfiber media, both wettable and non-wettable to compressor oil, in which the fractional penetration of the entire sandwich was measured by SMPS between about 30 and 700 nm. It is shown that the film penetration is substantially reduced for particles above about 100 nm in comparison to that of the dry media due to enhanced inertial deposition, while the channel penetration is generally higher across the board, probably because of a loss of active fiber in the partially saturated media. The last part of the paper is dedicated to practical consequences of this efficiency model. It is shown that the fractional efficiency for an arbitrary number of (identical) layers can be predicted quite accurately from the unit penetrations. Additional measurements of the total downstream concentration as a function of time are used to discuss and explain changes from start-up until steady state. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to assess short-term changes in pulmonary function in drill floor workers currently exposed to airborne contaminants generated as a result of drilling offshore. We also aimed to study the prevalence of pulmonary fibrosis using high-resolution computed tomography (HRCT) scans of another group of previously exposed drill floor workers.Methods: Pulmonary function was measured before and after a 14-day work period in a follow-up study of 65 drill floor workers and 65 referents. Additionally, 57 other drill floor workers exposed to drilling fluids during the 1980s were examined with HRCT of the lungs in a cross-sectional study.Results: The drill floor workers had a statistically significant decline in forced expiratory volume in 1 s (FEV1) across the 14-day work period after adjustment for diurnal variations in pulmonary function (mean 90 mL, range 30-140 mL), while the small decline among the referents (mean 20 mL, range − 30 to 70 mL) was not of statistical significance. Larger declines in FEV1 among drill workers were associated with the fewer number of days of active drilling. There were no signs of pulmonary fibrosis related to oil mist exposure among the other previously exposed drill floor workers.Conclusion: After 14 days offshore, a statistically significant decline in FEV1 was observed in the drill floor workers, which may not be related to oil mist exposure. No pulmonary fibrosis related to oil mist exposure was observed. [ABSTRACT FROM AUTHOR]

The aim of this experimental study is to investigate the separation performances of a new set of small cyclones. The diameter of these cyclones spans the range of 20–45 mm, which is the typical size of these devices when they are used for separating oil mist from blow-by gases in internal combustion engines. To reproduce the flow rates and oil load of combustion engines, we developed a flow bench, with a polydisperse aerosol generator producing engine oil droplets with diameter in a 0.3–10 µm range. Measurements of the aerosol particle concentrations upstream and downstream of the cyclone permitted the determination of the particle collection efficiency, for the six devices that were tested, with flow rates ranging from 20 to 200 Nl/min which are typical operating conditions. For the six cyclones, the geometry is normalized and all internal dimensions within the cyclone are proportional to its diameter. With the operating conditions of this study, the annular Reynolds number varied in the range 1.27×10 3 to 12.2×10 3 . From the measured fractional collection efficiency curves, dimensionless cut-off aerodynamic diameters were determined. These measurements have been compared with available correlations for the determination of this dimensionless diameter as a function of the annular Reynolds number. Different correlations are proposed in this study, for the evaluation of the cut-off diameter and for the shape of the collection efficiency. We were able to establish that the collection efficiency curve dimensionless slope is correlated to a Reynolds number. [ABSTRACT FROM AUTHOR]

The dependence of the differential pressure drop Δ p and the level of internal oil saturation S on the flow velocity of the air were investigated experimentally for a typical oil mist filter composed of oleophilic glass microfiber layers. Over a wide range of filter face velocities ( v = 5–70 cm/s) and liquid loading rates ( R = 15–125 mg / ( m 2 s ) ), and within the accuracy of the measurements, the “wet” pressure drop of the filter Δ p - Δ p 0 (i.e. the increase in Δ p over the “dry” pressure drop Δ p 0 ) was constant and did not show a systematic dependence on v . When decomposing the wet pressure drop into its components Δ p -jump and channel- Δ p , the Δ p -jump was also independent of the oil loading rate. The level of internal liquid saturation S was inversely proportional to v , with an empirical fit function S = 1 / ( 1 + v / v ∗ ) . The characteristic velocity v ∗ was found to depend on the oil loading rate, and presumably also depends on the media structure which was not varied here. This filter behavior is consistent with the “jump-and-channel” model proposed recently by Kampa et al. (2014). The experiments further showed that the “steady-state” pressure drop under constant filter operating conditions underwent a gradual increase with time (termed “ Δ p -creep”) that depends on operating conditions. This Δ p -creep diminishes gradually and was found to become stronger with increasing loading rate and filter face velocity. At the highest rate of increase (i.e. v = 70 cm/s, R = 125 mg / ( m 2 s ) ), an experiment lasting for 1100 h did not suffice to attain an asymptotic level for Δ p . Creep was found to be associated with a gradual increase in saturation and must therefore be classified as an(other) instability phenomenon in oil mist filters. [ABSTRACT FROM AUTHOR]

A comparative investigation was conducted on bubble formation and drop entrainment rates from oil mist filters in steady state operation, in order to establish a firm link between the two mechanisms. Rates were measured as a function of key filter operating parameters at different points of the filter surface, using wettable glass microfiber media as typical representatives of this application. Also, data for the thickness of the drainage film were obtained along the rear filter surface. For a given set of operating conditions, the bubble formation rate, the entrainment rate and the thickness of the oil film were found to increase roughly in proportion between the top and the bottom of the (vertically installed) filter. Bubble formation rates increased roughly tenfold along that path, from typically about 500–5000 bubbles per s and cm 2 , while entrainment rose from about 1000–3000 small drops per s and cm 2 . The drop size was narrowly confined to between about 1 and 2 µm, regardless of vertical position on filter surface and operating conditions. Both rates increased systematically with oil loading rate, but were relatively independent of the airflow velocity. The average number of fragment drops per bubble was on the order of 1, independent of oil loading rate. Independent measurements of bubble fragmentation on a free oil surface also gave an average fragment-to-bubble ratio close to unity for small bubbles (≤3 mm), but showed an increase ∼d 2 for larger bubbles. Overall, these measurements lend strong support to the contention that bubbling is the dominant mechanism of entrainment from the type of oil mist filter media investigated. [ABSTRACT FROM AUTHOR]

Lubrication oil used in refrigerant compressors forms oil mist in the compressor shell. Some of the oil mist is discharged into a refrigeration cycle with refrigerant and causes degradation of heat transfer in heat exchangers. Since the generation of the oil mist is related to the Weber number, it is necessary to measure the surface tension of the oil/refrigerant mixture before discussing the oil mist generation in the compressor. In this study, the maximum bubble pressure method was adapted to measure the surface tension of PAG (polyalkylene glycol) oil/CO 2 mixture. The density of the mixture needed for the measurement was also carried out. It was found that the surface tension of PAG/CO 2 mixture sharply decreases with an increase in the concentration of the refrigerant in the mixture. The surface tension of the mixture under 10 MPa and 100 °C is estimated to be 14.6 mN m −1 by an extrapolation. [ABSTRACT FROM AUTHOR]

Purpose: To study longitudinal changes in lung function in asphalt pavers and a reference group of road maintenance workers, and to detect possible signs of lung disease by high-resolution computed tomography (HRCT) scans. Methods: Seventy-five asphalt pavers and 71 road maintenance workers were followed up with questionnaires and measurements of lung function. Not every worker was tested every year, but most of them had four or more measurement points. The 75 asphalt pavers were also invited to have HRCT scans of the lungs at the end of the follow-up period. Results: Mean annual decline in forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV) of the asphalt pavers was 58 and 35 ml, respectively. Adjusted for age at baseline, packyears of smoking and BMI, the asphalt pavers had a significant excess annual decline in FVC and FEV compared to the references. The screedmen, the most exposed group of the asphalt pavers, showed a significantly larger decline in FVC than the other asphalt pavers ( P = 0.029). Fine intralobular fibrosis without evident cysts was identified with HRCT in three subjects (4 %). Conclusion: We conclude that our findings may indicate an excess annual decline in FVC and FEV related to exposure to asphalt fumes. The screedmen, who carry out their work behind and close to the paving machine, had the largest decline in lung function. The finding of adverse pulmonary effects in asphalt pavers calls for better technological solutions to prevent exposure. [ABSTRACT FROM AUTHOR]

Internal gas velocity fluctuations and their effects on the mist diffusion process were examined in a long horizontal pipe to understand oil mist transportation, particularly in the laminar-to-turbulent flow transition region. Three hot-wire anemometers and aerosol concentration monitors were used to deduce these effects as the two-phase mist flow gradually developed in the stream-wise direction. We found significant axial mist diffusion at Reynolds numbers ( Re ) < 1000 because of passive scalar transport by Poiseuille flow. However, this diffusion was restricted by the non-zero inertia of the mist at a Stokes number, O (10 −5 ), relying on the Brownian motion of the mist. At Re > 2400, a sharp mist waveform was maintained by a turbulent flow with active radial mixing. New data were obtained within the range of 1000 < Re < 2400, which cannot be explained by interpolation between the above-mentioned two states. The mist concentration displays multiple temporal peaks at Re < 2000 owing to perturbations of localized turbulence as well as radial anisotropy as being conveyed more than 2000-diameters in distance. This behavior is caused by intermittent disturbances induced by the pipe wall roughness, which sharply distorts the wall-aligned laminar mist layer left by parabolic axial stretching of local laminar flow. [ABSTRACT FROM AUTHOR]

[Display omitted] • A method for preparing glass fibre media with good oleophobic properties and mechanical strength was developed. • Trends in pressure drop and droplet penetration ratio of combined filters over time were investigated systematically. • Filter with decreasing pore size gradient had low pressure drop and best comprehensive performance for submicron droplets. • A mechanism of filter with increasing pore size gradient to improve filtration efficiency for submicron droplets was proposed. • A drainage layer was conducive to capturing re-entrained micron droplets. Pore size is a key factor that influences the removal of oil mist droplets by a coalescence filter. However, the influence of the pore size distribution among different filter layers on filtration performance has not been thoroughly explored. In this work, a method for preparing glass fibre filtration media with a specific structure as well as good oleophobic properties and mechanical strength was developed by combining the wet-spinning method and immersive modification. The prepared single-layer media were combined in various three-layer structures with increasing pore size gradient, decreasing pore size gradient and uniform pore size distribution. The trends in the pressure drop and droplet penetration ratio of the resulting combined filters over time were analysed systematically. The results demonstrated that in the combined filter, the first layer material had a significant influence on the filtration process and steady-state performance. Throughout filtration, the pressure drop of the filter with a decreasing pore size gradient had layering characteristics, which was conducive to capturing droplets within different particle size intervals in different stages and thereby relieving the operational pressure on different layers. Hence, the filter with a decreasing pore size gradient had a relatively low steady-state pressure drop and the best comprehensive filtration performance for submicron droplets. However, the filter with an increasing pore size gradient had the highest separation efficiency for submicron droplets and its concentration of steady-state downstream droplets was 19% lower than that in the filter composed of three layers of minimum pore size materials. The proposed mechanism by which the filter with the increasing pore size gradient improved the coalescence filtration efficiency for submicron droplets was based on capillary theory. [ABSTRACT FROM AUTHOR]

Grinding is a precision machining process which is widely used in the manufacture of components requiring fine tolerances and smooth finishes. Grinding is recognized as one of the most environmentally unfriendly manufacturing processes. The use of Minimum Quantity Lubrication (MQL) is of great significance in conjunction between large cutting fluids application and dry machining. It can reduce the amount of frictional heat generation and provide some cooling in the tool-workpiece interface and hence keep the workpiece temperatures lower than those in a completely dry machining. The ability to predict surface roughness and grinding force is important to many aspects of grinding process optimization, monitoring, and control. This paper presents the predictive modeling of surface roughness and grinding force based on a new semi-analytical model, and design and analyses of experiment, as a function of the grinding parameters, wheel types and coolant-lubricant properties. In addition, MQL oil flow rate, air pressure and nozzle distance to the grinding zone are adopted for evaluation by full factorial design of experiments. In this case, a 2 2 × 4 1 mixed full factorial design has been selected considering the number of factors used in the present study. The main effects of factors and interactions were considered in this paper, and regression equations were derived using response surface methodology (RSM). [ABSTRACT FROM AUTHOR]

A comparative investigation was conducted on wettable and non-wettable glass-fiber filters to clarify the mechanism(s) leading to flow induced entrainment of oil and to determine the influence of oil concentration and filtration velocity on the rate of secondary droplet production. Entrainment rates from a wettable and a non-wettable glass-fiber filter were measured over prolonged periods of time and with high time resolution by two optical techniques covering the drop size regions of about 0.5–10 μm and 150–2000 μm. The rates were compared with oil drainage patterns recorded over time, and with estimates of the forces required to detach drops by blow-off as compared to drop run-off (drainage) or to form air bubbles in a drainage film. It was found that initially oleophobic (i.e. non-wettable) media underwent a one-time transition in apparent wettability during normal operation, due to a change in drainage behavior from individual drops to a film-like flow pattern of oil. The transition was associated with a temporary increase (“burst”) in entrainment rate. After that, both types of media had steady-state entrainment rates that were comparable within a factor of two and depended mostly on the loading rate of the filter (which in turn determines the drainage rate), but showed little or no at all on filtration velocity. In conclusion, blow-off was ruled out as a mechanism contributing significantly to oil entrainment under the prevailing operating conditions, regardless of media wettability. Secondary droplets are due to fragments from bursting air bubbles, which are formed within the liquid film on the downstream face of the media. The entrainment burst of an initially non-wettable medium is also due to bubbles formed on draining oil drops. [ABSTRACT FROM AUTHOR]

A dielectric barrier discharge (DBD) reactor was fabricated and operated in two steps. In the first step (oil mist collection) oil mist aerosols were collected and in the second step (oil mist-to-gas conversion), without supplying oil mist particles but with supplying only clean air flow, collected oil mist particles were converted to gas species. An aerodynamic particle sizer, a scanning mobility particle sizer system, and a real-time gas analyzer were used to measure particle and gas concentrations at the inlet and outlet of the DBD reactor. The oil mist collection efficiency decreased from 78% to 21% but the oil mist-to-gas conversion efficiency increased from 6% to 95%, with increasing frequency from 1 kHz to 10 kHz. Low frequency caused higher amplitude of oscillating particle movement between the electrodes, resulting in higher collection efficiency. At a higher frequency, more electrons were generated, which resulted in the formation of more reactive oxygen species and thus increased subsequent oxidation. Increased surface temperature of the DBD reactor with higher frequency also contributed to higher oil mist-to-gas conversion efficiency. The DBD reactor can be applied to reduce oil mists generated in metal working and cooking processes. [ABSTRACT FROM AUTHOR]

Liquid entrainment from coalescence filter media—i.e. flow induced “blow-off” of previously deposited oil—in the form of droplets is poorly understood, for one because the generated spectrum is very wide and difficult to characterize with temporal and size resolution, especially for very large drops which carry most of the mass. Such filters operate at much lower flow rates than classical demisters, often in vertical orientation, with much finer geometries, and gravity plays no direct role for entrainment. We present a novel combination of four measurement techniques used to capture the entrained oil drop spectrum from filters during operation in the size range of 0.01–2400 µm. The diameter range below 10 μm combines two established real-time methods including an electrical mobility particle spectrometer (EMPS; <1 μm) and an optical particle counter (OPC; 0.3 to 10 μm). The diameter range above 170 μm is covered by a newly developed “large drop detection system” (LDDS) based on single particle light scattering. OPC and LDDS continuously count and classify all drops originating from the entire filter coupon with a time resolution of 1 min. The EMPS was operated intermittently, following brief switches from aerosol to clear air flow. Drops in the size range between OPC and LDDS were collected and sized by an off-line method. This measuring system was applied to two representative types of glass microfiber media operated with oil mist generated from compressor oil, in order to characterize time resolved drop formation rates and spectra in the range of nanometers to millimeters. Wettable and non-wettable filter media were found to show similar entrainment characteristics, each with multi-modal drop spectra having two pronounced peaks in the ranges of 1–2 μm and 200–300 μm, respectively. During steady-state operation both modes were generated quasi-continually, the large drops at the rate of a few drops per hour and cm 2 of filter surface, the micron size drops 10 3 –10 4 times more frequently. Available indirect evidence suggests the same underlying entrainment mechanism for both types of fibrous media, namely the break-up of air bubbles formed periodically on the oil that drains on the downstream filter face. Direct detachment (blow-off) of large drops is unlikely at the prevailing operating conditions. [ABSTRACT FROM AUTHOR]

The “wet pressure drop” of oil mist filters (i.e. the increase in differential pressure of the air flow due to loading of the filter with liquid) is presented as a function of two mechanisms by which coalesced oil is transported through the filter. These mechanisms operate in separate regions of the filter and make separate (and separately measurable) contributions to the overall wet pressure drop. This new concept, which was first formulated qualitatively in a phenomenological model by Kampa et al. (2014) , leads to semi-quantitative predictions regarding the dependence of pressure drop Δ p and saturation S on filter operating conditions, filter properties and liquid properties. These predictions are first formulated and then validated for a range of wettable and non-wettable filter media in combination with 4 mineral oils of different viscosity. The key findings, summarized below, are consistent with the model and apply to both wettable and non-wettable media. Oil transport across media interfaces (i.e. transitions between regions of different porosity and/or wettability) was associated with a relatively sharp increase in pressure drop ∆ p and oil saturation S over a very thin layer of the filter (a “∆ p jump”). The magnitude of this ∆ p jump was determined by the media properties. It correlated well with the respective static break-through pressures for oil or air, but did not depend on the oil viscosity and loading rate of the filter (at constant air velocity). Oil transport through channel regions of the filter (i.e. the regions connecting interfaces) was associated with a linear increase in ∆ p with channel length and liquid throughput. The corresponding saturation level S was relatively flat throughout the channel region and lower than at an interface. (Both quantities are media dependent, of course.) An increase in oil viscosity μ (at constant oil throughput) led to different responses depending on filter wettability. [ABSTRACT FROM AUTHOR]

Highlights: [•] Two distinct transport mechanisms for coalesced liquid govern the “wet” pressure drop. [•] Transport across capillary interfaces causes Δp jumps associated with film formation. [•] Internal transport occurs via multiple parallel channels with constant Δp/length. [Copyright &y& Elsevier]

In this study, a method is developed to determine the oil mist characteristics for the minimal quantity lubricant process. The oil mist is characterized by the size, velocity, and volume flow rate of its particles. In each case, a specific measurement process is used: the laser diffraction granulometry method, the particle image velocimetry, and the gravimetric method. These methods are used in the case of static and simple models with different inner channels. Experimental tests have been done with the same inner channel as the existing spindle inner channel. Different output models with different inner canalizations have been tested, using these experimental processes. The main goal is to control the characteristics of output oil mist as a function of the input oil mist device parameters. [ABSTRACT FROM AUTHOR]

Abstract: One of the problems that encounter most biogas plants is the fouling that takes place due to the poor quality of biogas utilised for energy purposes. In such a situation it is necessary to measure and control concentrations of main and hazardous components in a biogas. Indeed, the purification systems become a crucial elements of operational plants. In the presented work the analytical procedures and standardisation of analytical methods for determination of main biogas components: trimethylsilanol, volatile methylsiloxanes, volatile organic compounds, oil mist, and halogenated components originating in biogas were developed. For this, gas chromatography has been coupled with various kinds of detection methods i.e. electron capture, thermal conductivity, flame ionization, and mass spectrometry. Furthermore, the sampling procedure based on direct biogas absorption allowed to exclude the extraction process. Consequently, the time of analysis was significantly reduced. The field study showed clearly, that concentration of siloxanes in analysed samples was determined in the range from 20.6 to 361.8mg/Nm3. Therefore, the impact of biogas silica-contaminants on a running gas-motor was explained and extensively discussed. VMSs and TMSOH concentrations were recalculated and expressed in toluene equivalent, as well as the interpretation of obtained data was provided. Although, we have successfully proven, that the toluene equivalent (T eq) is not an appropriate differentiating factor for siloxanes concentration, although the content of TMSOH might be expressed as T eq. The promising results obtained in this study indicate that this novel sampling procedure, and the standardisation of analytical routines can become a promising approach to accomplish the procedure of biofuel analysis. [Copyright &y& Elsevier]

Objectives: There are no recognized analytical methods for measuring oil mist and vapours arising from drilling fluids used in offshore petroleum drilling industry. To inform the future development of improved methods of analysis for oil mist and vapours this study assessed the inter- and intra-laboratory variability in oil mist and vapour analysis. In addition, sample losses during transportation and storage were assessed. Methods: Replicate samples for oil mist and vapour were collected using the 37-mm Millipore closed cassette and charcoal tube assembly. Sampling was conducted in a simulated shale shaker room, similar to that found offshore for processing drilling fluids. Samples were analysed at two different laboratories, one in Norway and one in the UK. Oil mist samples were analysed using Fourier transform infrared spectroscopy (FTIR), while oil vapour samples were analysed by gas chromatography (GC). Results: The comparison of replicate samples showed substantial within- and between-laboratory variability in reported oil mist concentrations. The variability in oil vapour results was considerably reduced compared to oil mist, provided that a common method of calibration and quantification was adopted. The study also showed that losses can occur during transportation and storage of samples. Conclusions: There is a need to develop a harmonized method for the quantification of oil mist on filter and oil vapour on charcoal supported by a suitable proficiency testing scheme for laboratories involved in the analysis of occupational hygiene samples for the petroleum industry. The uncertainties in oil mist and vapour measurement have substantial implications in relation to compliance with occupational exposure limits and also in the reliability of any exposure–response information reported in epidemiological studies. [ABSTRACT FROM AUTHOR]

Abstract: The aims of the present study were set out to measure size distributions and estimate workers’ exposure concentrations of oil mist nanoparticles in three selected workplaces of the forming, threading, and heat treating areas in a fastener manufacturing plant by using a modified electrical aerosol detector (MEAD). The results were further compared with those simultaneously obtained from a nanoparticle surface area monitor (NSAM) and a scanning mobility particle sizer (SMPS) for the validation purpose. Results show that oil mist nanoparticles in the three selected process areas were formed mainly through the evaporation and condensation processes. The measured size distributions of nanoparticles were consistently in the form of uni-modal. The estimated fraction of nanoparticles deposited on the alveolar (AV) region was consistently much higher than that on the head airway (HD) and tracheobronchial (TB) regions in both number and surface area concentration bases. However, a significant difference was found in the estimated fraction of nanoparticles deposited on each individual region while different exposure metrics were used. Comparable results were found between results obtained from both NSAM and MEAD. After normalization, no significant difference can be found between the results obtained from SMPS and MEAD. It is concluded that the obtained MEAD results are suitable for assessing oil mist nanoparticle exposures. [Copyright &y& Elsevier]

Abstract: In medium to heavy duty diesel engines, ever increasing power densities are threatening piston''s structural integrity at high engine loads and speeds. This investigation presents the computational results of the heat transfer between piston and an impinging oil jet, typically used to keep the pistons cool. Appropriate boundary conditions are applied and using numerical modeling, heat transfer coefficient (h) at the underside of the piston is predicted. This predicted value of heat transfer coefficient significantly helps in selecting right oil (essentially right oil grade), oil jet velocity, nozzle diameter (essentially nozzle design) and distance of the nozzle from the underside of the piston. It also predicts whether the selected grade of oil will contribute to oil fumes/mist generation. Using numerical simulation (finite element method), transient temperature profiles are evaluated for varying heat flux (simulating varying engine loads) to demonstrate the effect of oil jet cooling. The model, after experimental validation, has been used to understand the transient temperature behavior of the piston and the time taken in achieving steady state. High speed CCD camera is used to investigate the oil jet breakup, localized pool boiling and mist generation due to impinging jet on the piston''s underside. [Copyright &y& Elsevier]

Workers in the drilling section of the offshore petroleum industry are exposed to air pollutants generated by drilling fluids. Oil mist and oil vapour concentrations have been measured in the drilling fluid processing areas for decades; however, little work has been carried out to investigate exposure determinants such as drilling fluid viscosity and temperature. A study was undertaken to investigate the effect of two different oil-based drilling fluid systems and their temperature on oil mist, oil vapour, and total volatile organic compounds (TVOC) levels in a simulated shale shaker room at a purpose-built test centre. Oil mist and oil vapour concentrations were sampled simultaneously using a sampling arrangement consisting of a Millipore closed cassette loaded with glass fibre and cellulose acetate filters attached to a backup charcoal tube. TVOCs were measured by a PhoCheck photo-ionization detector direct reading instrument. Concentrations of oil mist, oil vapour, and TVOC in the atmosphere surrounding the shale shaker were assessed during three separate test periods. Two oil-based drilling fluids, denoted ‘System 2.0’ and ‘System 3.5’, containing base oils with a viscosity of 2.0 and 3.3–3.7 mm2 s−1 at 40°C, respectively, were used at temperatures ranging from 40 to 75°C. In general, the System 2.0 yielded low oil mist levels, but high oil vapour concentrations, while the opposite was found for the System 3.5. Statistical significant differences between the drilling fluid systems were found for oil mist (P = 0.025),vapour (P < 0.001), and TVOC (P = 0.011). Increasing temperature increased the oil mist, oil vapour, and TVOC levels. Oil vapour levels at the test facility exceeded the Norwegian oil vapour occupational exposure limit (OEL) of 30 mg m−3 when the drilling fluid temperature was ≥50°C. The practice of testing compliance of oil vapour exposure from drilling fluids systems containing base oils with viscosity of ≤2.0 mm2 s−1 at 40°C against the Norwegian oil vapour OEL is questioned since these base oils are very similar to white spirit. To reduce exposures, relevant technical control measures in this area are to cool the drilling fluid <50°C before it enters the shale shaker units, enclose shale shakers and related equipment, in addition to careful consideration of which fluid system to use. [ABSTRACT FROM PUBLISHER]

Respiratory problems are observed in machinists using soluble metalworking fluid (MWF). Evidences suggest that these problems could be related to the aerosolized microorganisms and their byproducts from MWF. To establish MWF aerosol exposure thresholds and to better understand their effect on human health, these aerosols must be fully characterized. This article evaluates airborne microorganisms and aerosols from soluble MWF in the working environment. Air quality parameters (endotoxin levels, culturable airborne microorganisms, fluid mist, inhalable dust and air exchange rates) were evaluated at 44 sites, in 25 shops in Quebec, Canada. Microorganism concentrations were also measured in MWF. Culturable airborne bacteria concentrations were low, ranging from 1.2 × 101 to 1.5 × 103 CFU (colony forming units) m- 3, even for metalworking fluid highly contaminated by bacteria (up to 2.4 × 109 CFU mL- 1). Inhalable dust varied between < 0.1 to 2.6 mg m- 3, while air exchange rates were mostly below the standard (4 h- 1) for this type of workplace, between 0.6 to 14.2 h- 1. Only nine of 44 sites respected the suggested minimum value for air exchange rates. Fluid mist ranged from 0.02 to 0.89 mg m- 3, which is below the threshold limit value (TLV) (ACGIH) of 5 mg m- 3. Airborne endotoxin concentrations ranged from undetectable to 183 EU m- 3 (endotoxin units), showing no correlation with airborne microorganisms or inhalable dust. Most workstations respected the suggested minimum values for fluid mist and showed low concentrations of airborne endotoxin, culturable microorganisms and inhalable dust despite fluid contamination, even when air exchange rates were below the recommendations. Airborne Pseudomonas pseudoalcaligenes was recovered from many sites at significant concentrations. Health-associated risks following exposure to this microorganism should be further investigated. [ABSTRACT FROM AUTHOR]

The objective of this study was to develop regression models to predict concentrations of oil mist and oil vapor in the workplace atmosphere in the shale shaker area of offshore drilling installations. Collection of monitoring reports of oil mist and oil vapor in the mud handling areas of offshore drilling installations was done during visits to eight oil companies and five drilling contractors. A questionnaire was sent to the rig owners requesting information about technical design of the shaker area. Linear mixed-effects models were developed using concentration of oil mist or oil vapor measured by stationary sampling as dependent variables, drilling installation as random effect, and potential determinants related to process technical parameters and technical design of the shale shaker area as fixed effects. The dataset comprised stationary measurements of oil mist (n = 464) and oil vapor (n = 462) from the period 1998 to 2004. The arithmetic mean concentrations of oil mist and oil vapor were 3.89 mg/m3 and 39.7 mg/m3, respectively. The air concentration models including significant determinants such as viscosity of base oil, mud temperature, well section, type of rig, localization of shaker, mechanical air supply, air grids in outer wall, air curtain in front of shakers, and season explained 35% and 17% of the total variance in oil vapor and oil mist, respectively. The developed models could be used to indicate what impact differences in technical design and changes in process parameters have on air concentrations of oil mist and oil vapor. Thus, the models will be helpful in planning control measures to reduce the potential for occupational exposure. [ABSTRACT FROM AUTHOR]

Abstract: Single-stage and two-stage tubular electrostatic precipitators were designed. A nitrogen stream containing very fine droplets of fogging oil was forced through the electrostatic precipitator chamber. It was found that 98.6wt% of the oil droplets present in the turbulent jet were mechanically collected on the inner walls of the test chamber. When the electrode was energized at 13kV, 92.37wt% of the droplets that had not been mechanically separated were collected in single-stage mode. The collection efficiency was increased to 93.18wt%, when the electrostatic precipitator was operated in two-stage mode. Voltage–current (V–I) characteristics of the single-stage and two-stage electrostatic precipitators were studied in detail for different test conditions. Nitrogen impurities played a major role in determining the V–I characteristics. They became less relevant with the introduction of mist in the nitrogen stream, presumably due to the presence of water vapor in the gas. The two-stage tubular electrostatic precipitator was scaled up and tested on a fluidized bed pilot plant used for the pyrolysis of biomass. A droplet collection efficiency of 95wt% was observed. Such demisters will extend, to the product recovery train, the process intensification gains of short residence time processes such as fast pyrolysis. [Copyright &y& Elsevier]

This study was set out to characterize size distributions of oil mists in three workplace atmospheres of the forming, threading, and heat treatment in a fastener manufacturing industry and to assess their exposures to workers. Particle size segregating samplings were conducted on the workplace atmospheres of the three selected industrial processes by using the modified Marple 8-stage cascade impactor (m-Marple). We found that mass median aerodynamic diameter (MMAD) of the fine mode and coarse mode fell to the range 0.309–0.501μm and 8.16–13.0μm, respectively. The fractions of inhaled particles exposed to different regions of the respiratory tracts found that the alveolar region was consistently higher than both head and tracheobronchial regions in all three studied exposure groups. Personal inhalable oil mist samplings were conducted on workers in the three selected processes revealed their exposure levels as: threading workers (2.11mg/m3)>forming workers (1.58mg/m3)>heat treatment workers (0.0801mg/m3). The estimated respirable exposure concentrations for both forming and threading workers (1.34mg/m3 and 1.40mg/m3, respectively) were higher than the level known for “increased risk of pulmonary injury” (0.20mg/m3) suggesting that appropriate control measures should be taken to reduce their exposures to the oil mists of the respirable fraction immediately. [Copyright &y& Elsevier]

In this paper, the influence of oil mist on the tool temperature in cutting is investigated experimentally. The turning of a carbon steel with oil mist applied is performed, and the temperature of the alumina tool at the tool-chip interface is measured using a two-color pyrometer. The tool temperature in dry cutting at a cutting speed of 300 m/min is ∼1060 °C, but it is ∼1000 °C when oil mist is supplied. In intermittent turning, the oil mist has more effect on the tool temperature because it is supplied more efficiently to the tool-chip interface. In end milling with the oil mist applied, the tool temperature at the flank face is ∼580 °C at a cutting ,speed of 400 m/min, though in dry cutting it is ∼660 °C. [ABSTRACT FROM AUTHOR]

The American Conference of Governmental Industrial Hygienists (ACGIH®) has recommended that the threshold limit value (TLV®) for mineral oil mists be dramatically lowered, based on epidemiological evidence of respiratory health effects among machinists exposed to various metalworking fluid mists. A review of the literature regarding respiratory health effects from either metalworking or non-metalworking fluids suggest that machinists may have experienced slightly higher prevalence of common respiratory symptoms and mild and reversible cross-shift changes in some measures of pulmonary function. However, the inconsistency and potential for both random and systematic error in this body of literature argue against drawing definitive conclusions. There is also no substantive evidence that any of these effects led to permanent disease or impairment. The most likely causal agents for respiratory effects in these workers are microbial contaminants in water-based metalworking fluids, not straight mineral oils. This is consistent with the epidemic outbreaks of hypersensitivity pneumonitis, bronchitis, and asthma reported at some work sites using water-based metalworking fluids. This highlights the importance of frequent cleaning and fluid changes for metalworking fluid reservoirs, as part of a systematic approach to managing metalworking fluid aerosol exposures. A dramatic drop in the TLV for mineral oil mists would not resolve this problem. [ABSTRACT FROM AUTHOR]

Effective, economical control of metalworking fluid mists at the source is important, because exposure to these mists may cause adverse health effects. This study investigated performance changes over time for industrial collectors that removed metalworking fluid mist in the laboratory and in a transmission plant. Aerosizers were used to measure the efficiency of each stage in several multistage collectors as a function of mist droplet diameter, for up to one year of continuous operation. Metal-mesh, first-stage filters operated at low pressure drops and were effective at removing droplets larger than 3 to 5 Θ m in diameter. Some second-stage filters worked better than others. Both ''65 percent'' and ''95 percent'' cartridge filters failed after only a few weeks; their efficiencies decreased substantially over that time. Pocket filters and cylindrical cartridges used as second-stage filters also decreased in efficiency for submicron droplets. Whereas filters for solid particles load continuously to form a dust cake that increases efficiency, mist filters form no cake and load only to the point where collection equals drainage. As a mist filter loads, the interstitial gas velocity increases, so that efficiency decreases for small droplets that collect by diffusion. Although a third-stage 95 percent DOP filter showed important decreases in efficiency over time for submicron droplets, third-stage HEPA filters operated with efficiencies that consistently approached 100 percent for droplets of all sizes, even after one year of operation. These results suggest that the performance of second-stage filters can be improved if they can be made to drain collected liquid more effectively. For high efficiency, mist collectors should use a HEPA filter as a final stage. [ABSTRACT FROM AUTHOR]

Sampling methods to determine occupational exposures to metalworking fluid mists are subject to bias. Light-scattering devices may respond differently to variations in particle size, shape, and refractive index. Gravimetric samplers are prone to evaporative losses of semi-volatile components. The performance of two light scattering devices, an electrostatic precipitator, and filters followed by gravimetric analysis was investigated when measuring metalworking fluid mist in laboratory and field settings. Laboratory tests with soluble oil and field tests with soluble oil, straight oil, and semi-synthetic fluid showed significant evaporative losses from filters. Light-scattering devices tended to overestimate mist concentrations when mass median diameters were less than about 2 mum and to underestimate mist concentrations when mass median diameters were larger. Filters will underestimate occupational exposures to metalworking fluid mists when semi-volatile components are present. conditions. [ABSTRACT FROM AUTHOR]

Oil mists can cause respiratory distress and have been linked to skin and gastrointestinal cancers in workers. Standard concentration assessment methods call for sampling these mists with fibrous or membrane filters. Previous experimental studies using glass fiber (GF) filters and polyvinyl chloride and polytetrafluoroethylene membrane filters indicate that mist sampled onto filters may volatilize. A model has been developed to predict the evaporation of mist collected on a fibrous sampling filter. Evaporation of retained fluid from membrane filters can be modeled by treating the filter as though it is a fibrous filter. Predictions from the model exhibit good agreement with experimental results. At low mist concentrations, the model indicates that evaporation of retained mineral oil occurs readily. At high mist concentrations, significant evaporation from the filters is not expected because the vapor accompanying the airborne mist is already saturated with the compounds in the oil. The findings from this study indicate that sampling mineral oil mist with filters in accordance with standard methods can lead to estimates of worker exposure to oil mist that are too low. [ABSTRACT FROM AUTHOR]

Oil mist emitted during cooking is one of the major sources of atmospheric particulate matter in urban areas. A conventional electrostatic precipitator (ESP) is used in some large restaurants; it requires regular electrode cleaning to maintain particle collection performance. However, oil mist generated during cooking is viscous and difficult to clean with water. Herein, we introduce a methodology and a device for cleaning collected oil mist using surface dielectric barrier discharge (surface-DBD) plasma. Our device uses corona discharge for the collection of oil mist. Subsequently, the oil mist collected is decomposed to gas-phase species by surface-DBD plasma. A maximum collection efficiency of 93.25% (for 230 nm di-ethyl hexyl sebacate (DEHS) particle) is obtained at a flow velocity of 1.5 m/s. The maximum oil mist decomposition efficiency is 96.4%. More than 80% of the decomposed oil mist is converted to CO 2 and CO under all test conditions. Some of the byproducts other than CO and CO 2 are released as particles. Higher frequency results in higher oil mist decomposition efficiency, but also higher byproduct formation of particles. The mechanism of oil mist decomposition by surface-DBD plasma is discussed using optical emission spectroscopy data. [Display omitted] • Oil mist is electrostatically collected by corona discharge. • Methodology of decomposing collected oil mist using surface-DBD is introduced. • Most of the decomposed oil mist is converted to CO and CO 2. • Some of the byproducts other than CO and CO 2 are released as particles. • Energy for oil mist collection is significantly lower than previous studies. [ABSTRACT FROM AUTHOR]

Electrostatic precipitators (ESPs) are widely used by machining industries to remove oil mist due to the high efficiency, low pressure drop and low energy consumption. In this paper, the effects of oil mist concentration, relative humidity and oil film thickness on the collection efficiency of ESPs were studied. The experimental results showed that discharge current and collection efficiency both decreased with increasing oil mist concentration, and the collection efficiency of fine oil droplets decreased more obviously than that of large-size oil droplets. When the oil mist concentration increased from 100 mg/m3 to 300 mg/m3, collection efficiency of oil droplets with a size of 0.33 μm dropped from 87.13% to 73.53%, while the efficiency for the droplet size of 1.25 μm only dropped from 90.7% to 84.1%. Increasing the relative humidity caused a considerable decline in discharge current due to the decrease in ion mobility, but an appropriate increase in humidity was conducive to the improvement of collection efficiency. The stable status of oil film thickness on electrode plate was obtained (about 10 μm in the current study), and the stable current density decreased almost 11% due to the oil film. Compared with the oil droplets deposited on the electrode wires, the oil droplets deposited on the plate caused more decrease of collection efficiency of ESPs. The decrease in collection efficiency effected by the electrode plate with oil film was twice that of the electrode wires with oil contamination. • The effect of wires with oil contamination on the efficiency was investigated. • The relationship between deposit morphology and current density was analyzed. • Oil film thickness on the plate was verified to reach a steady state. • The effect of oil holding capacity on the efficiency was investigated. [ABSTRACT FROM AUTHOR]

The notice of intended change for the threshold limit value (TLV®) for mineral oil mist contains a notation for human carcinogenicity. A description is provided of the current European regulatory approach used to distinguish between carcinogenic and non-carcinogenic mineral base oils on the basis of oil refining process and chemical marker information. This approach has proven effective in creating a market situation in the countries of the European Union where many customers require severely refined, non-carcinogenic oils. It is recommended that ACGIH® consolidate the distinction between poorly and severely refined base oils in the recommended TLV for mineral oil mist and use different toxicological considerations to derive exposure control guidelines. [ABSTRACT FROM AUTHOR]

Conventional aerosol filters typically have homogeneous wettability with limited filtration ability especially for small oil mists. Increasing filtration efficiency using thicker filter pad or finer fibers both result in considerable increase of pressure drop, which adversely increases energy consumption. It remains a challenge to develop effective filter materials that can effectively remove oil mists from air at a low flow resistance. Here, a novel concept about improving oil mist filtration efficiency without apparently increasing pressure drop using a fibrous filter with asymmetric wettability across the thickness is demonstrated. Dip‐coating and single‐side electrospraying are used to make fibrous filter have a homogeneous superoleophobicity or directional oil‐transport function. When the two are combined together, they show a filtration efficiency as high as 99.45% for small oil mists (size 0.01–0.8 µm) and nearly 100% for large oil mists (size 0.5–20 µm) with a pressure drop of 9.29 kPa. With the same thickness and fibrous structure, our directional oil‐transport/superoleophobic filter has higher quality factor than those with homogeneous oleophilic, superoleophobic, and asymmetric wettability of other superoleophilic/superoleophobic combinations, for both small and large oil mists. Directional oil transport‐superoleophobic filters may lead to a novel, high‐performance, low energy consumption oil mist separation technology. A novel concept about improving oil mist filtration efficiency without increasing pressure drop has been developed based on fibrous filter with asymmetric wettability across the thickness. The dual‐layer filter consisting of a directional oil‐transport layer and a superoleophobic layer shows incredible filtration performance surplus to the dual layers filters with various wettability features. [ABSTRACT FROM AUTHOR]