23.10.2020  Author: admin   Wood Gifts You Can Make
This small vacuum force cannot break the boundary layer. It is possible to retrofit a system by adding dampers or changing fan speed to restore system balance after it has been modified, but dust removal system design effect is always prudent to evaluate the potential impact to the system prior to making any changes. Designing an Efficient Dust Collection System. Each system has advantages and disadvantages. Each system will likely have requirements or characteristics that will necessitate specific design considerations that will differentiate it from other systems. Next Next post: Managing Scope Creep. This contact can be an idler roll, filter, impression roller or printing plate dust removal system design effect stay on the final product.

If possible, stay away from axial fans on your dust collector system. Consideration should also be given to the material that is used for the fan blades and housing. For example, abrasive dusts will quickly erode fan components that are made of soft metal. Incompatibilities that could lead to corrosion should also be considered. Why are differential pressure gauges used in dust collection systems? Using a differential pressure gauge to measure pressure drop through a collector is an effective method of monitoring the health of a dust collection system.

Air that flows through a newly installed system with minimal leakage, a properly functioning fan, and filters that are clean will experience a pressure drop as it travels through the collection unit. This drop is normal. System manufacturers typically provide normal pressure drop figures for their units. Regular collection of pressure drop data is recommended to track gradual or sudden changes.

Gradual changes are likely caused by filters or ductwork becoming clogged, whereas more sudden changes could be the result of system or fan damage, torn or missing filters, or leakage that is allowing water or air into the system.

In either case, pressure drop data can be used to see trends and prevent full blown problems before they result in the system having to be shut down. What is a DHA? Any industrial facility that creates dusts or uses powders is mandated by NFPA to complete a DHA to identify the presence of combustible dusts and establish a plan for eliminating or mitigating potential risks associated with these dusts in their facilities. The deadline for completion of the DHA is September The DHA should be as simple or as complex as the process and needs to be formally documented and needs to be updated as collection points are added, or new raw materials are brought into the facility.

The main purpose of the DHA is to educate the owner and operators on the true hazards and dangers they are facing with their dust, and to make sure they take the proper precautions with it. The DHA is a tool to prevent loss of life, equipment, production time, and capital.

What are dampers? Dampers are used in dust collection systems to control the airflow to specific branches of the ductwork. This is done by opening or closing the damper because air, like water, travels the path of least resistance. By using a damper, you are changing the path of least resistance for the air travelling in the system.

Every dust collection system should have a manual damper near each hood or pickup point to allow the system to be balanced. This flexibility allows airflows to be varied between collection points, depending on the changing operational needs of the entire system. Without this type of control, an unbalanced system could cause too much air to be pulled from one area causing loss of viable product while in another area not enough airflow is available to capture dust.

Soft connects, or spaces between flanges, are occasionally used to control airflow at a pickup point. Dampers are a much better solution, as they allow the ability to close off branches that are not being used. Ductwork is usually the largest component of a dust collection system and often the most overlooked. Depending on the size of your system, the ductwork can span hundreds of feet and have dozens of side streams. The ductwork is essentially a transportation network that is used to move dusty air from one place to another.

As with transportation system design, a good ductwork layout will utilize straight lines when possible and attempt to limit the overall size of the system. Larger systems requiring many elbows and transitions will experience inefficiencies due to flow and velocity losses caused by friction. Ductwork diameter is dependent upon the material being conveyed and the distance between the collector and pickup points. The correct diameter helps ensure that the required balance between velocity and flow to move the dust is maintained.

Care should be taken whenever adding or removing drops to a system after its installation, as any modification has the potential to negatively affect the flow and velocity in the system.

It is possible to retrofit a system by adding dampers or changing fan speed to restore system balance after it has been modified, but it is always prudent to evaluate the potential impact to the system prior to making any changes. A good dust collection system is reliant upon properly designed hoods to capture dust. Capture velocity is the required air speed that is necessary to overcome any surrounding air currents that would otherwise prevent the flow of dust into the hood or enclosure.

An improperly designed hood will fail to effectively collect dust or require more airflow than should be needed. Hoods usually should be placed as close to the source as possible for the best results. The best size and shape are dependent on many factors, but hoods usually incorporate tapered or conical designs improve capture velocity and reduce friction in the system. It provides recommended hood designs, airflow requirements, and sizes.

Dust collection manufacturers and designers, HVAC consultants, and manufacturer representatives can also be consulted. A sensible way to limit the capital expenditure required when installing a dust collection system is to use a used collection unit. Initial system design can proceed as it normally would, laying out collection points, calculating the required airflow, determining duct sizes, and calculating static pressure.

From this initial design work, a shopping list of requirements can be generated. If a used collector is available that can meet or exceed the requirements of the system, then it should be fully inspected and evaluated for any mechanical, electrical, or structural problems.

It may be helpful to consult the manufacturer of the used unit to help assess its condition. The availability of and cost of replacement filters and other parts should also be considered. That is why periodic system performance evaluations are vital. This list of 10 questions is certainly not an exhaustive list of questions that should be asked when evaluating your dust collection system.

Each system will likely have requirements or characteristics that will necessitate specific design considerations that will Dust Removal System Design 7th Edition differentiate it from other systems.

But, having a basis of general knowledge about system design and operation will allow you make more informed judgments of system performance. For more information, call or visit www. Dust Collection Systems: 10 Common Questions. Hide comments.

More information about text formats. Text format Comments Plain text. Web page addresses and e-mail addresses turn into links automatically. There are several technologies available today to reach that goal. For all of them it is necessary to remove the particle by using a vacuum and filter system.

An air knife may do its job to break the boundary layer, but it also distributes the particles into the nearby environment, where they get caught by the substrate again further down the production line. Dust removal systems, which are working with a geometrically simple slot in a vacuum tube are very inefficient as soon as higher web speeds are reached. This small vacuum force cannot break the boundary layer.

Only an aerodynamic nozzle, which is mounted closely above a backup roll to the substrate surface can generate a forceful enough high velocity airflow to break efficiently the boundary layer even at highest web speeds. At the same time it has to be ensured that this airflow has to have enough volume to remove all particles including the air volume arriving with the substrate due to the boundary layer. In many cases electrostatic charge on the substrate is a main factor to increase contamination and additional difficulties for its removal.

It is well known, that insulating materials such as paper, film or foil generate static charges Dust Removal System Design Keys by friction. These charges will ensure that particles, which are already on the substrate surface being attached even better to it and additional particles from the nearby environment will be collected.

The smaller the gap between particle and substrate surface, the greater is the force of the electrostatic field holding the particle down. This is why a static control system must be installed prior to the cleaning process to guarantee a neutralized substrate surface and therefore an efficient removal of all particles. The ultimate goal of the cleaning procedure is to remove all particles prior to the contamination sensitive production process.

The requirements can vary between particle sizes of bigger than 50micron for the printing and packaging applications down to particle sizes of less than 2 microns for the film, foil or clean room applications. Unfortunately is it not economical to develop a system that meets all requirements. A label printer will not invest in a non-contact cleaning system, which can clean down to 2 micron in particle size.

Today's market offers a verity of cleaning systems using different technologies and solution approaches. Each system has advantages and disadvantages. What kind of boundary layer does exist during the process? Has electrostatic charge a big influence to the application?



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