Dust control systems

The health and safety issues outlined herein for particleboard also apply to MDE. A special note should be made of the fact that, because the MDF raw material is of dry fiber base, there exists in MDF a large component of very small, broken, dust-like wood fibers. These contribute to the dust concerns in the manufacturing areas, requiring exceUent dust-control systems, good housekeeping, and personal protection. 

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Exhauster and Motor Air movers for LVHV systems are not conventional fans. The low static pressures needed to operate LVHV systems can be generated by multiple-stage centrifugal (turbine-type) exhausters. These utilize high-precision rotating blades that can be damaged by dust. Consequently, it is always necessary to have an air cleaner in an LVHV dust control system to protect the fan. The low static pressures also require air volume flow rates to be corrected to standard conditions for exhauster selection. 

The correct application of either sizing technique will result in a duct network that works well on air. It is equally important to ensure that each air flow is adequate to transfer all the particulates from the hood/enclosure to the collection and/or cleaning device. Unfortunately, many dust control systems have been designed and/or are being operated with little or no regard for what actually has to go through the hood-duct network. This can result in ... 

Inefficient performance of the overall dust control system. 

At this stage, operators of dust control systems should at least be aware of these various issues and their relative importance, which will vary from problem to problem Hence, it is essential that the engineer or consultant responsible adopts a systematic approach to the solution of the problem in which all the relevant issues are considered and dealt with in the appropriate order. 

In its NEP, OSHA points out that for workplaces not covered by 1910.272, but where combustible dust hazards exist within dust control systems or other containers, citations under section 5(a)(1) of the OSH Act (the General Duty Clause) may generally be issued for deflagration (fire) or explosion hazards. National Fire Protection Association (NFPA) standards should be consulted to obtain evidence of hazard recognition and feasible abatement methods. Other standards are applicable to the combustible dust hazard. For example, if the workplace has a Class II location, then citations under 29 CFR 1910.307 may be issued to those employers having electrical equipment not meeting the standard s requirements. 

To develop inhouse dust control systems for livestock to improve the welfare of workers and livestock and reduce dust emission from buildings. 

The design of a suitable dust control system for a particular application requires knowledge of dust generation and air entrainment. The interaction of these two parameters with the process (e.g. solids throughput, powder properties, temperature, drop height, velocity) also must be considered for this purpose. Unfortunately, the existing techniques to... 

Many operations within the laboratory start with weighing. It is difficult to undertake precise weighing in conventional laboratory fume hoods, as the airflow and vibration inside an operating fume hood often disturb the balance. In order to accommodate the need for an engineered control at this scale of operation, dust control systems have evolved known as ventilated weighing safety enclosures or powder weighing hoods. Key characteristics of a ventilated weighing safety enclosure include ... 

Unless operated as a closed system, mixing, sifting and blending equipment should be fitted with dust control systems. 

Dust control systems usually include hoods and enclosures connected to a local exhaust ventilation system that discharges to cyclone collectors and scrubbers or a baghouse in series. The most common type of control equipment is the baghouse these are increasing in use as more stringent pollution control codes are adopted. These filters provide excellent collection efficiency with little or no visible emissions and the collected dry fines are sometimes usable in concrete mixes. However, if the exhaust gas temperature is at or near the dew point of the gas, condensation of moisture on the fabric filters is always a possibility and poses a serious fire hazard. The other type of the commonly used control equipment is the venturi wet... 

Crushers Crushers emit dust primarily from two points, the discharge and the feed. Dust control measures are not usually considered in the design of a crusher. However, the use of shrouds or enclosures for crushers can contain the dust so that a dust control system can operate more efficiently. In installing crushers, the following measures are recommended (1) a crusher feedbox with a minimum number of openings should be installed, and rubber curtains should be used to minimize dust escape and airflow and (2) the crusher should be choke-fed to reduce air entrainment and dust emission. Dust escape at the crusher discharge end can be minimized by properly designed and installed transfer chutes. 

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