The exhaust fan provides the motive force for the dust collection system. The exhaust fan has a performance curve that defines how much airflow it will pull at a certain static pressure. When you turn on a fan, it will ramp up and increase the airflow until reaching the maximum static pressure it can provide.

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.

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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.

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.  Air, like water, travels the path of least resistance.  By using a damper, you are changing the resistance to the air.  Every dust collection system should have a manual damper near each hood/pickup point to balance the system.  This makes sure that the system is properly operating.  An unbalanced system could cause too much air to be pulled from one area (causing loss of product) while in another area not enough airflow is available to capture dust.  Other times, a soft connect (space between flanges) is used to control airflow at a pickup point.  However, this isn’t very efficient.  This keeps the airflow in that area constant, but it’s picking up air from an area where it isn’t required.  A damper would work much better, since you are only moving the air in the area you need.  Soft connects are only advantageous when you are looking to cool down an airflow using outside air.  Dampers can also be used to shut off portions of the system that are not being used, thereby allowing a smaller system.

So when you are looking at your dust collector system, don’t forget dampers.  They allow you to optimize your system.

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

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

A few things can be done to address this, such as changing fan speed, adding dampers, modifying ductwork, etc.  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.

So when you are looking at changing your dust collector system, review the system parameters or hire someone to review so that you do not cause additional issues.

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