Aaberg ventilation

On June 3, 1998, in Rotterdam a 165-m cone roof tank containing methyl tertiary butyl ether (MTBE) exploded while being washed, causing a fatality and launching the 1.4 tonne roof a distance of 100 m. The tank was 10 m high by 4.5 m diameter. Initially the tank contained 27% MTBE vapor with the balance nitrogen. However, as washing proceeded a vacuum tmck was used to suck sludge, water, and residual MTBE out of the tank bottom. As the vacuum hose lost contact with the liquid layer, the resulting negative pressure intermittently sucked air into the tank via the top manway, which held a high pressure washing device. Turbulent mixing by the washing jets helped form a flammable mixture in the tank. The explosion occurred during the fourth cleaning cycle and the fatally injured man was blown from the roof shortly after adjusting the washing device. Two static mechanisms considered were a static discharge involving the water mist and a static discharge from an ungrounded vacuum hose. The latter would have to be ruled out before attributing this incident to a charged mist mechanism involving brush discharges or charged water slugs. The company involved had previously ventilated their tanks to the air to reduce flammable vapor concentrations to a safe level, but this approach had been abandoned owing to local emission constraints.  [c.146]

While it is relatively easy to remove volatile solvents such as ethyl ether and acetone during a drying process, less volatile solvents may persist at about 1 wt% or more in the product. The rate of evolution of solvents may be a slow process and difficult to estimate without practical testing. The worst case can be determined for a closed container at the highest anticipated temperature. For example, the temperature in a shipping container can be measured using a maximum-minimum thermometer so that the maximum transit temperature is found. This might exceed 50°C. Closed container evolution tests on a fresh powder sample can then be done to determine the maximum gas concentration that can develop. If this exceeds about 50% of the gas LFL, there is the potential for sensitized hybrid dust-gas mixtures. A separate problem would arise should the maximum gas concentration approach the LFL, which could indicate a gas ignition risk in the container. Tests have shown that powders containing upward of 0.2-0.5wt% solvent should be evaluated for these hazards. A possible solution, short of higher efficiency drying or extended powder storage in a ventilated area prior to shipment, is to use a high ventilation shipping container or ventilated hopper car. Special attention should be given to avoiding flammable gas evolution from powder packages that might be air shipped. A separate issue is powders that evolve flammable gas via ongoing reaction such as with atmospheric moisture (eg some metal alkoxides) or degradation of peroxides in the formulation. While the hybrid mixture hazards are similar to those with solvent-containing products, the source of flammable gas is in such cases renewable, and precautions need to be taken throughout the handling process. In all cases attention should be given to the possibility of gas concentrations markedly increasing with increased time and temperature. For example, a gas sample taken from a hopper car might underestimate the gas concentration that develops after shipment to a customer. Similarly, the gas concentration might increase after transfer to a powder silo heated in sunlight.  [c.173]

Comparing different areas of the building or comparing indoor to outdoor conditions in order to confirm that a control approach has the desired effect of reducing pollutant concentrations or improving ventilation. Establish baseline conditions so that they can be compared to concentrations at other times or locations, such as concentrations in outdoor air, concentrations in areas where no symptoms are reported, expected "background" range for typical buildings without perceived lAQ problems.  [c.225]

Another lAQ control strategy is to clean the air. Air cleaning is usually most effective when used in conjunction with either source control or ventilation however, it may be the only approach when the source of pollution is outside of the building. Most air cleaning in large buildings is aimed primarily at preventing contaminant buildup in HVAC equipment and enhancing equipment efficiency. Air cleaning equipment intended to provide better indoor air quality for occupants must  [c.231]

The most economical and successful solutions to lAQ problems tend to be those in which the operating principle of the correction strategy makes sense and is suited to the problem. If a specific point source of contaminants has been identified, treatment at the source (e.g., by removal, scaling, or local exhaust) is almost always a more appropriate correction strategy than dilution of the contaminant by increased general ventilation. If the lAQ problem is caused by the introduction of outdoor air that contains contaminants, increased general ventilation will only make the situation worse (unless the outdoor air is cleaned). It is important to make sure that one understands the lAQ problem well enough to select a correction strategy whose size and scope fit the job. If odors from a special use area such as a kitchen are causing complaints in a nearby office, increasing the ventilation rate in the office may not be a successful approach. The mitigation strategy should address the entire area affected.  [c.234]

Ventilation is required in buildings for many different reasons. In this section, the emphasis is on industrial environment however, the general method of approach is common to all systems for the following reasons  [c.726]

This is the usual method of ventilation in domestic dwellings and many small office buildings and workshops. New standards, however, require buildings to have set ventilation rates, which require mechanical ventilation systems. However, as covered later, use is made of natural ventilation to control the air-change rate, regardless of the external conditions. This approach is not practical for industrial applications.  [c.727]

Demand-controlled ventilation (DCV) is one approach to reduce energy consumption due to ventilation, that is gaining popularity in both industrial and nonindustrial applications. It is used in cases where ventilation requirements vary with time, regularly or irregularly. The control is based on a specified level of indoor air quality by means of continuous measurement of the parameters, that are expected to primarily determine the lAQ, such as the concentration of the main contaminant liberated from the production process. The principle is thus similar to the one in some better-known nonindustrial applications, e.g., CO2 levels in rooms with dense human occupancy (theaters, classrooms, etc.) or nicotine concentration in smoking rooms. See also Section 9.6.  [c.802]

The most popular approach to solve these problems is to use experience and good engineering judgment. A quick experiment may be another solution. A computer simulation is a third option. All those approaches may eventually lead to success. This chapter presents various methods of computer simulation for industrial ventilation design.  [c.1026]

Multizone airflow models are based on a network approach. The building is subdivided into zones or nodes, representing spaces of perfectly mixed air. Each zone is characterized by its zone node temperature and pressure and possibly its contaminant concentrations. The zone nodes are linked by conductances (airflow elements), modeling the airflow paths (cracks, openings, ducts, etc.). Pressure coefficients, relating local wind pressure at the building fac ade to the reference wind pressure, can be attributed to external nodes. Not only wind effects but also buoyancy effects resulting from air density differences are taken into account. In addition, pressure and flows induced by components of a mechanical ventilation system (fans, ducts) are also considered. EIs-ing air mass conservation, a system of nonlinear equations is built and iteratively solved for the zone pressures, providing airflow rates through all conductances. From these, zone-related flows are determined.  [c.1083]

The study is performed for a representative section of the hall. A network model was established for COMB, considering doors, openings ar floor level, and rhe large openable ventilation hoods on the roof. Relationships are established for the air-exchange rate as a function of the temperature difference be tween inside and outside for different opening configurations. The effect of a temperature gradient in the hall is evaluated additionally. As a conservative approach, wind effects are neglected.  [c.1099]

The carrying out of visualization techniques or measurements is one approach to obtain answers to these questions. Computer simulation is another method that is now becoming a more exact science. A third, essential approach is to depend on experience and good engineering judgment. All the above methods may eventually lead to success however, the effort and cost of the work may differ considerably. This chapter describes the measurement and visualization techniques that can be applied in industrial ventilation problems.  [c.1106]

Several tools can be used to evaluate the environmental consequences of an industrial ventilation project. Some of the most common methods used are covered in this chapter. The life cycle assessment tool is considered in detail, as it is a comprehensive and product-oriented approach that is covered by international standardization. Other tools, such as risk assessment, cost-benefit  [c.1357]

Using formalized risk assessment techniques for industrial ventilation projects may complicate the issue more than necessary. The work environment and its exposure conditions are the focus. However, when evaluating new technology, including waste management, the risk assessment approach may be valuable.  [c.1369]

The primary goal of the Industrial Ventilation Design Guidebook is to develop a systematic approach to the design of air technology systems based on current scientific research and engineering knowledge on a global basis. There is no internationally accepted handbook available that describes the basic theories and science behind the technical solutions for industrial air technology. Our objective has been to develop a much-needed scientific reference book that covers the whole field of industrial air technology based on validated and updated technology from leading scientists, engineers, and researchers worldwide. This preface outlines why there is a need for a reference handbook, how this goal has been achieved, what has been achieved, and the intended audience for this book.  [c.1551]

Each aspect of energy use in a home influences the comfort, health, and safety of the occupants as well as their utility bills. An energy-efficient home properly utilizes systems solutions to effectively reduce energy use while improving the quality of life for its occupants. A systems solutions approach examines the interactive effects of all of the components within the house. Wliile there is no definitive set of features, the building science community is converging on eight common elements to reduce home energy use when properly incorporated into the systems solution air scaling, insulation, windows, duct scaling, heating and cooling, lighting and appliances, mechanical ventilation, and diagnostic testing.  [c.204]

An increasingly popular strategy is to give individuals control over their workplace conditions. The benefits of this approach were documented at West Bend Mutual Insurance Company s 150,000-square-foot building headquarters m West Bend, Wisconsin. The design used a host of energy-saving design features, including efficient lighting, windows, shell insulation, and IIVAC (heating, ventilation, and air conditioning).  [c.670]

FIGURE 10.80 A typical Aaberg ventilator unit. v[c.959]

The vapors of the organic solvents used in the preparation of cellulose ester solutions represent a potential fire, explosion, or health ha2ard. Care should be taken to provide adequate ventilation to keep solvent vapor concentrations below the explosive limits. Mixing equipment should be designed to ensure that solvent temperatures do not approach their flash point during the mixing cycle. All equipment must be electrically grounded to prevent static discharge, and appropriate precautions should be followed as recommended by the manufacturer of the solvents.  [c.259]

Pest control activities that depend upon the use of pesticides involve the storage, handling, and application of materials that can have serious health effects. Common construction, maintenance practices, and occupant activities provide pests with air, moisture, food, warmth, and shelter. Caulking or plastering cracks, crevices, or holes to prevent harborage behind walls can often be more effective than pesticide application at reducing pest populations to a practical minimum. Integrated Pest Management (IPM) is a low-cost approach to pest control based upon knowledge of the biology and behavior of pests. Adoption of an DPM program can significantly reduce the need for pesticides by eliminating conditions that provide attractive habitats for pests. If an outside contractor is used for pest control, it is advisable to review the terms of the contract and include IPM principles where possible. The following items deserve particular attention. Schedule pesticide applications for unoccupied periods, if possible, so that the affected area can be flushed with ventilation air before occupants return. Pesticides should only be applied in targeted locations, with minimum treatment of exposed surfaces. They should be used in strict conformance with manufacturers instructions and EPA labels. General periodic spraying may not be necessary. If occupants are to be present, they should be notified prior to the pesticide application. Particularly susceptible individuals could develop serious illness even though they are only minimally exposed. Select  [c.212]

Ventilation modification is often used to correct or prevent indoor air quality problems. This approach can be effective either where buildings are underventilated or where a specific contaminant source cannot be identified. Ventilation can be used to control indoor air contaminants by  [c.229]

COMPBRN in is a single-room zone fire model for probabilities risk as.sessment calculations. It models fires in an open or closed compartment using a 2-layer zone model approach. Thermal radiation and flame propagation are included. It requires a large amount of input room geometry ventilation, doorway information, fuel bed geometry, orientation, thermal and combustion properties, ignition fuel location and properties, ignition temperatures of fuel, burning rate as a function of incident heat flux (surface-controlled burning) or ventilation (ventilation-controlled burning), and a definition of which fuel elements exchange thermal radiation with each other and with ceiling and walls. It outputs total mass burning rate, total heat release rate, hot gas layer temperature and depth, indication of fuel cell damage and burning, radiative and total heat fluxes to targets, fuel cellmass, flame height over each fuel cell, flame temperature over each fuel cell, fuel cell temperature, and heat transfer coefficient (convective) for each cell. It only is applicable to single-room, pre-flashover fire compartments. Quasi-steady state assumptions are made it is highly  [c.367]

The epidemiological data have the advantage of being based on human exposures, However, the results of epidemiological studies often remain inconclusive because of various confounding factors and poor exposure assessments. In addition, epidemiological data are available for only a small number of agents. The target level approach, presented in chapter 6 of this book, uses inherently large safety margins in relation to OELs. Unfortunately, it is also applicable only for the most common exposures. Since zero exposure is the best, the. 3LARA (As Low As Reasonably Achievable) principle, adopted in radiation protection, is, in principle, also a good approach for other exposures.7 0 However, even then the question, how low is low enough, may remain unanswered. This chapter has been written with the intention of lowering the threshold for a ventilation engineer to seek a toxicological consultation and to provide the fundamental background information needed to utilize the available toxicological literature. Occupational hygienists may also find the text to be a useful compact overview of the essential concepts of toxicology.  [c.241]

Commercial products do exist that integrate shrouded and ventilated grinding wheels and other hand-held tools. It may be possible to find an existing LVHV-type product that will work well for some applications, requiring only to be connected to an appropriate air handling system. However, it is also sometimes necessary to make custom-fabricated LVHV nozzles for some hand-held tools and for essentially all fixed-machine dust-generating tools. I he best approach is to consider the following  [c.863]

Among these is COST Action G3 on industrial ventilation. Thi,s action was launched in 1996 and comprises to date more than 60 experts from fourteen COST countries and from institutions of four nonmember countries, its main nh(ective, a.s stipulated in the Memorandum of Understanding of the action. is to produce a basis for a Design Guidebook by a multidisciplinary approach based on gathering rhe expert knowledge which exists internationally, further developing it and making it available for the designers,  [c.1547]

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Industrial ventilation design guidebook (2001) -- [ c.852 , c.853 , c.854 , c.855 , c.856 , c.857 , c.858 , c.859 , c.860 , c.861 , c.862 , c.863 , c.864 ]