As most exhaust fans are centrifugal fans, the curves show that the lower the airflow, the higher the static pressure. This means that as the airflow increases the static pressure decreases. When the airflow in a system changes, this means the static pressure required in the system has changed, so the system performance has changed per the exhaust fan curve.

When The Airflow Is Higher

With higher airflow, the operating point will move further right on the fan curve. Generally, this won’t affect the fan much. The efficiency of the fan could change, but the overall affect would be minimal. If this change takes the fan off its curve, then you could develop operational issues with the fan. However, this isn’t a common occurrence.

When The Airflow Drops

A much greater issue is when the airflow drops. This moves the operational point to the left of the curve. Most centrifugal curves have the static pressure of the fan level out as the airflow decreases. If you get to this flat part of the curve, the fan could provide unstable performance, where the airflow jumps around. For example, the fan curve can show that between 0 ACFM and 800 ACFM the fan provides 12” W.C. This means when you get into this area your airflow can fluctuate anywhere from 0 to 800 ACFM. This can cause issues throughout your system and isn’t a good place on the curve for the fan to operate.

When you are operating a dust collection system it is imperative that you maintain the airflow in the system within design criteria. If it increases too much it can cause added expenses, maintenance, and product loss. If it decreases too much it will let dust escape, lower removal efficiency, and possibly create dangerous environments. So, we highly recommend regular, if not continuous, monitoring of your process airflows to be sure you’re operating within design parameter.

To improve efficiency and safety, there is no substitute for an on-site inspection by an experienced expert. Click here to connect with a member of our engineering team about fan best practices in your dust collection system. 

The post Exhaust Fans: The Motive Force of a Dust Collection System first appeared on Aerodyne Environmental.]]> https://www.dustcollectorhq.com/what-are-the-benefits-of-using-a-vfd-on-a-dust-collection-exhaust-fan/ Wed, 26 Jul 2017 19:11:00 +0000 https://www.dustcollectorhq.com/what-are-the-benefits-of-using-a-vfd-on-a-dust-collection-exhaust-fan/ The VFD allows you to control the airflow thru your sys. by changing the fan speed.It also allows you to dial the system to the most efficient operating point.

Variable Frequency Drives allows for you to control the airflow through your system by changing the fan speed without breaking the bank.  Without VFDs, one has to manually open or close dampers, creating high manual labor cost. Furthermore, if there are multiple dampers on the system, then tampering with the opening and closing of any one damper, can cause the airflow balance to be off and can increase the static pressure of the system.  

The VFD allows you to control the airflow of the fan, rather than allowing a constant high air output, as would be the case when dampers are being used. VFDs give the system the airflow that is required while lowering electrical costs.  VFDs can further lower costs by replacing motor starter control panels. All in all, using a VFD is the smart way to control your airflow.

If you are having operational issues on your dust collection system contact Aerodyne at 440-543-7400 or dc@dustcollectorhq.com to help you problem solve your dust collection problems.

The post The Benefits of Using a VFD On a Dust Collection Exhaust Fan first appeared on Aerodyne Environmental.]]>

Dust collection systems consist of four major components. All of them are important and can cause a dust collection system to underperform. The major components are the exhaust fan, dust collector, ductwork, and hoods/pickup points. While the exhaust fan provides the motive power to collect dusty air, its performance is affected by each of the other components. This means that if one of these components isn’t operating as designed, the whole dust collection system will be affected.

Dust collection ductwork is usually by far the largest component and often the most overlooked. Depending on the size of your industrial dust collection system, the ductwork can span hundreds of feet and have dozens of branch lines. The ductwork is like railroad tracks—it moves the dusty air from one place to another.

Often times, additional lines will be added to a dust collector system after installation. Without proper evaluation of the system, this could negatively affect the performance of the whole system. This means that just because the dust collector system was operating correctly before, it might not after an additional pickup point or hood is added. What happens is that when you add additional pickup points, you change the balancing of the system. This could change the airflow to each and every hood and pickup point in the system, so while the system was originally adequately venting an area, it might not after a change.

Several steps can help address these issues, including changing fan speed, adding dampers, modifying ductwork, or rebalancing the dust collection system. The main thing you need to keep in mind is that if you slow the airflow through ductwork too much, you begin to build up dust within the line.  This will further restrict your airflow and become a fire / explosion hazard.

Whenever you are planning to modify your dust collection system, review the system parameters or hire someone to review so that you do not cause additional issues.

Learn about the questions you should be asking to make sure you’re buying the right dust collector for your application. Get your whitepaper now.

If you are having operational issues on your dust collection system, contact Aerodyne at 440-543-7400 or dc@dustcollectorhq.com.

Today we are discussing the exhaust fan.  The exhaust fan could be the most important component in the dust collection system.  It provides the motive force for the whole system.  If it isn’t performing as required, the system will fail.  The proper fan impeller (wheel) must be used if the fan is to operate correctly.

There are three types of wheels/impellers:

• Radial wheel (Ex. open material handling and material handling) – These wheels should be used when the fan is on the dirty side of a dust collector or after a dust collector where a large amount of dust remains in the airstream (ex. after drop out box). The wheel is designed so it can handle dust in the air.  The open type wheel is used when there is a high dust loading and/or the dust is fibrous.  Its design helps prevent the dust from wrapping around the wheel.

• Air handling wheel – The air handling wheel is designed for clean airstreams or extremely light dust loading. These wheels should always be used on the clean side of and dust collector and never on the dirty side.  They are usually more efficient in air movement than the radial wheels.

• Axial wheel – These wheels are usually never used on dust collection systems. They will move a lot of air, but without much force behind them.  If possible, stay away from axial fans on your dust collector system.

If you are having issues with the fan on your dust collector, check the wheel.  Make sure you are using the proper type.    

Find out more at Dust Efficiency Clinic.

If you are having operational issues on your dust collection system, contact Aerodyne at 440-543-7400 or dc@dustcollectorhq.com.

Hoods / Pickup Points

Hoods mark the start of an industrial dust collection system. Hoods are designed for providing a specific airflow at a minimum velocity while picking up particulate in the air.  The hood type, location and number are usually specific for your application.  The Industrial Ventilation Manual, the standard for ventilation put out by the American Conference of Industrial Governmental Hygienists, provides guidelines for velocity ranges to provide the proper ventilation.  A velocity lower than suggested could cause dust to escape the hood.  Adding additional hoods to an existing system could cause the airflow (thereby pickup velocity) to drop below the minimum suggested, thereby making a notable reduction of performance.

Ductwork

If dust and airflow are blood, ductwork is the circulatory system. The ductwork of a properly designed ventilation system should be sized so that it has the lowest possible pressure drop and have a minimum velocity.  Best ductwork practices for avoiding a pressure drop include keeping the ductwork as straight as possible, minimizing turns, and keeping the duct size larger.  Since the ducts are carrying dust, a minimum velocity is required lest the dust settle in straight sections.  These accumulations will cause increased resistance and are a fire and explosive hazard.   Usually, a velocity of the air over 4,000 FPM prevents dust from accumulating.  Keeping ductwork in a standard size keeps costs down and assures availability if additional or replacement ductwork must be added.

Dust Collectors

Some dust collectors are less sensitive to added airflow than others.  A cyclone’s pressure drop will increase as airflow increases through the system, but a baghouse or cartridge collector’s removal efficiency will decrease if airflow is increased too much.  Many of these are very particulate specific; a cartridge collector for an airstream containing wood dust could handle higher airflows than one for silica dust.  Contacting the dust collector manufacturers is the best way to understand the capabilities of a collector.

Exhaust fans

The exhaust fan is the most important equipment in a dust collection system, providing the motive force to collect the air-dust mixture.  In many cases, companies will add additional pickup points and not change the fan, causing less air to be pulled from each of the existing pickup point.  When looking at the airflow in a dust collection system, make sure to calculate the total airflow and static pressure required, then check to see if the existing fan can handle it under different conditions, such as open dampers or increased speeds. If not, a new fan will be required.

For more information on how Aerodyne’s GPC line of compact, efficient dust collectors can fit into your existing industrial dust collection system and be tailored to your airflow, click the button below, call us at (440) 543-7400, or email us at dc@dustcollectorhq.com.