Dust collectors can have issues with material bridging in the hopper. 

Round or Square Airlocks

A standard collector uses round or square flanged airlocks instead of a rectangular design better suited where bridging persists.These designs are great for standard dust that doesn’t bridge.  They are easy to fabricate, thereby keeping cost low.  However, the uniform dimensions of the flange allow the dust to be equally supported on all sides, creating a more stable environment for a dust bridge to form.  One way to counteract this is by over-sizing your airlock. An example would be using a 12” rotary valve instead of an 8” valves.  While oversizing the airlock lowers the chance of bridge forming.  A bridge can still form due to shape of the flange. 

Better Airlocks: Rectangular Rotary Valve

A better way would be to use a rectangular rotary valve.  Since the rotary valve has a rectangular flange, dust trying to bridge over the opening isn’t equally supported.  And any bridge trying to form across the long axis will be unstable and begin to bow down into the valve opening, where the rotors will grab them and destroy the bridge, allowing the free flow of dust out of the hopper.

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Bridging Dust?

Try the Aerodyne Mighty Whopper.

Aerodyne’s Mighty Whopper rotary valve has over-sized rectangular inlet and outlet. 

 

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5 Signs Your Dust Collection System Needs Maintenance

Is your dust collection system working at peak efficiency? A quick, do-it-yourself examination may identify symptoms that your system needs a check-up.

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To learn more about which dust collector, please contact our experts at 440-543-7400 or visit our website: www.dustcollectorhq.com

Do the rotary valves under your dust collectors cause maintenance headaches?  Are they clogging?  Are you having to drop everything and assign extra labor to fix them?

The disadvantages of Rotary Valve

Most dust collectors are equipped with a motor-driven rotary airlock valve that empties contents from the hoppers. Rotary valves have been used for many years and are probably the most widely used airlock design. However, maintaining rotary valves is difficult and time consuming. These valves run continuously, regardless if dust is present, which leads to wasted electricity. In addition, the valves can wear out rapidly, resulting in costly repairs and replacements.

Best Alternative: Aerodyne Vacu-Valve ^®

A highly cost-effective alternative is Aerodyne’s Vacu-Valve ^®  Trickle Valve System. The Vacu-Valve relies on the negative pressure of the material handling system to hold the duckbill sleeve closed. As the dust or material builds up, the sleeve is forced open, allowing the contents to discharge. Once emptied, the negative pressure then immediately closes the duckbill again. This trickle valve system requires no lubrication, power, or controls. Materials that would normally jam or wear out a rotary airlock valve, the Vacu-Valve handles with ease. There is a variety of duckbill sleeve options designed for specific applications; and the Aerodyne Vacu-Valve ^® is available in an open or closed design, to further accommodate the particular application.

Aerodyne’s Vacu-Valve ^® is the solution! Have a look at this infographic and to learn how the Vacu-valve solves these issues and improves the discharge efficiency of your baghouse, filters and cyclones.

 

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How Do Vacu-Valve Dust Valves Work?

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To learn more about which dust collector, please contact our experts at 440-543-7400 or visit our website: www.dustcollectorhq.com.

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To improve efficiency and safety, there is no substitute for an on-site inspection by an experienced expert. Click below to start with a free 20-minute phone consultation by clicking the button.

We all know that getting the oil change in our car regularly is important to the car being able to get you around when you need it.  However, your dust collector needs regular maintenance too.  The dust collector system consists of hoods, ductwork, air-material separators (cyclones, baghouse, cartridge collectors, wet scrubbers, etc.), explosion protection equipment, airlocks, instrumentation, and exhaust fans. 

All of these items should be checked at least once a year to make sure they are operating correctly.  The following points briefly describe what each piece of equipment needs:

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1. Hoods

• Visual inspection to make sure they haven’t been damaged during the year.
• Measure airflow velocity to make sure they are collecting the design airflow.
• If a local damper is located by hood for balancing, make sure it is operable and in the correct position.

2. Ductwork

• Visual inspection to make sure no holes have developed.
• Measure air velocity through ductwork to make sure designed airflow is correct.
• If possible, visual inspection of duct internal to make sure dust isn’t building up.

3. Air Material Separators

• Measure pressure drop across the separator to see if it is within parameters.
• Inspect cleaning process (baghouses and cartridge collectors) that they are operating properly (timing, valves opening, air pressure, etc.). See operations and maintenance manual.  Often time, listening to the system will let you know if it is operating correctly.
• Monitor recycle line pressure and overflow in wet scrubbers.
• Visual inspection of vessel walls to be sure there are no holes.

4. Explosion Protection Equipment

• NFPA requires yearly inspection, following the manufactures manual is very important so the explosion protection equipment will protect the facility, equipment, and workers as it was designed.
• Some explosion protection equipment such as chemical suppression should be done by factory trained personnel.

5. Airlocks

• Rotary valves
  • Should be checked to see they are still spinning
  • Bearings should be greased and temperature measured to make sure they aren’t overheating
  • On explosive applications the rotor clearance should be measured to make sure it still complies with NFPA 69.
• Pneumatic valves (slide gates, double flap valves, etc.)
  • Valves should be tested to make sure they are still operating as designed.
  • Air pressure should be measured, to be sure it is still within design parameters.
• Motorized valves (rotary valve, double flap valves, etc.)
  • Bearings should be greased
  • Bearing temperature should be measured to be sure they aren’t overheating
• Trickle valves
  • The sleeve should be inspected to be sure it is still sealing
  • During operation confirm that material is still draining and material hasn’t bridged above it.

6. Instrumentation

• Level gages, pressure gages, VFDs, pH meters, zero speed switches, etc. all have different maintenance requirements.
• Follow the manual of the specific model for maintenance and inspection.

7. Exhaust Fans

• The fan housing should be inspected to make sure no holes are present.
• The voltage and amps should be measured to make sure it is operating at its design condition.
• The bearings should be greased and temperature checked to be sure they aren’t overheating.
• The fan’s vibration should be checked along with checking to see if any abnormal noise is emanating from the fan.

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To learn more about which dust collector, please contact our experts at 440-543-7400 or visit our website: www.dustcollectorhq.com.

To improve efficiency and safety, there is no substitute for an on-site inspection by an experienced expert. Click below to start with a free 20-minute phone consultation by clicking the button.

 

Click below and watch our video to identify five signs that may diagnose a sluggish system so that you can return your system to full efficiency.

Look under almost any dust collector and you will see a rotary airlock valve spinning its rotor and emptying the collected contents from the hopper. These valves have long been used to maintain a seal in vacuum dust collection systems while simultaneously providing an escape route for the dust. The advantages of a rotary airlock for dust collectors include, automatic hopper emptying, minimal vacuum pressure loss, and the many options available to meet specific application needs. Rotary valves can be custom fit to handle high temperatures, harsh chemical environments, and abrasive materials. Rotary valves do however, have a few major drawbacks.

Because rotary airlocks are sealed tight to the atmosphere they can be very difficult to clean. Cleaning a rotary valve often involves removing the drive assembly, end plate, and finally the rotor. This process can take hours to perform. Rotary valves are also expensive to operate. Typically, these valves are left running continuously, even when there is no dust present in the hopper. This not only wastes electricity but puts undo wear on the valve. Repair and replacement parts for rotary airlock valves can be quite costly as well. Even with these shortcomings, the rotary airlock remains the industry standard for most dust discharge applications.

One alternative which has been gaining popularity is a non-powered automatic dust discharge valve. These valves, like the Armadillo and Platypus Vacu-Valves from Aerodyne, rely on the negative pressure (max -18" W.C.) of a dust collector to hold a rubber sleeve closed to maintain an airlock. As the weight of the dust in the hopper builds up, the sleeve is forced open and dust is discharged from the valve. Leaf springs inserted into the valves sleeve also help to counterbalance the vacuum. A video demonstration of how this works is available here. The valves are available with a variety of sleeve materials for different applications. While these valves can not be used in every dust collection system they are a very economical alternative to expensive rotary valves.

The Vacu-Valves from Aerodyne are priced at a fraction of the cost of standard rotary airlock valves and require no electricity to operate. These valves have no controls and require no lubrication. They easily handle abrasive materials that would jam or wear out a rotary valve.

To learn more about which dust collector valve is right for you, please contact our experts at 440-543-7400 or click on the button below to get our infographic, Vacu-Valve is a Simpler Solution.

 

When your dust collectors are having issues, one of the first places to look is the airlock valve.  Often times, dust is hygroscopic and when outside air leaks into the system, humidity follows.  This can cause the dust to absorb the humidity and become sticky or harden like cement.  This can lead to plugged filters, hoppers and damage to rotary valves.  While rotary valves are the industry standard airlock, they constantly allow air leakage.  A low leakage valve is required. Double dump valves however are very low leakage, since there is no direct connection to the outside atmosphere.  The valve always isolates the conditions above it from the conditions below it.  This minimizes air leakage, thereby minimizing humidity from affecting the dust.

So if you have a non-explosive application that is hygroscopic, look into a double dump (flap) valve.

Find out more information now.

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

In order for a dust collector to operate at its peak performance, the hopper has to be isolated from the outside.  This means either the dust bin/receptacle is “hard connected”, meaning there are no air leaks or an airlock is used.  An airlock isolates the dust collector hopper from the outside, while allowing the collected dust to exit the system.  Common airlocks are rotary valves, trickle valves, double dump valves, and knife gates.  Some airlocks are low leakage (double dump valve and trickle valves) while others have continuous leakage (rotary valves). 

Airlocks are important because without them air will enter (system under vacuum) or leave (pressurized system) through the dust discharge valve.  If the system is under vacuum, the air entering the system from the dust discharge will re-entrain the dust back into the clean air, thereby lowering removal efficiency.  If the system is under pressure, air will blow out of the bottom, spreading dust everywhere, creating unnecessary maintenance cost for the facility.

If the system is dealing with an explosive dust, an airlock should be used to prevent an explosion from propagating from the dust discharge flange.  Specially designed rotary valves are used to prevent this.

Furthermore, airlocks allow you to change the dust bin without shutting off the system.  If you don’t have an airlock, when you need to change your dust bin, you either have to turn off the system, or operate the unit without any isolation. 

So when you are spending money to capture your dust in a dust collector, don’t forget to put an airlock on it, so you will have the best performance possible.

Read our article on what type of airlock valves to use in particular applications.

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