Dust Collection and Valves Blog

Un-powered Valve Saves Initial Cost and Operating Costs over Rotary Airlock Valve

Posted by Tom Hobson on Dec 13, 2018 9:30:00 AM

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.

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Topics: rotary valves, trickle valve, vacu-valve, airlocks valve, airlock, maintaining air valves

Dust Collection Systems: 5 Best Solutions of Dust Collection Airlocks

Posted by Tom Hobson on Apr 24, 2017 8:30:00 AM

When you are specifying your dust collector, don’t just settle on a rotary valve.  There are other airlocks that might be better suited for your application.  Other airlocks include the double dump (flap) valve, trickle valve, and knife gate.  Not to mention just bypassing an airlock totally and connecting a hopper directly to the bottom of the dust collector.

The following will help you figure out which is the best solution:

  1. Rotary valve – Use this if you have combustible dust. However, you will have constant air leakage across the valve.
  2. Double dump valve – Use this if you want to minimize air leakage. The Double Dump works great with big, chunky material or if you’re worried the material may wrap around a rotary valve rotor.
  3. Trickle valve – Use to save money and time. Requires a vacuum and usually a fine, free-flowing particle to work effectively.  It’s low cost and easy maintenance makes it very attractive when suitable.
  4. Knife Gates – Used for periodic emptying of the dust collector hopper into another container. Knife gates come in a variety of design (knife gate, slide gate, orifice type, etc.).  Depending on the design, they can provide an airtight seal or not.  However when open, the airlock is lost.
  5. Direct couple to a hopper – Used with low dust loading and could require the dust collector to be turned off during changing of the hopper. Also be-careful to take into account the lower hopper when used on a combustible dust application.

When you are looking for an airlock, don’t just automatically use a rotary valve.  Doing so may cause operational and maintenance issues in the future.  It could also cost you more money.  If you would like help in picking the best airlock, don’t hesitate to contact Aerodyne at 440-543-7400 or dc@dustcollectorhq.com. He is available to help you to solve your dust collection issues.

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Topics: knife gate valve, rotary valves, double dump valve, trickle valve, direct couple to hopper

Dust Collection Systems: Rotary Valves and NFPA-69

Posted by Tom Hobson on Apr 10, 2017 8:30:00 AM

When you have a combustible dust, not only does your dust collector require to be protected against a deflagration, but the airlock must contain the event.  NFPA-69 allows the use of a rotary valve as long as the following:

  1. Deflagration isolation by flame quenching (close-clearance valves) or
  2. Deflagration isolation by material blocking (product layer above the valve)

Most rotary valves use flame quenching to achieve compliance with the spec.  Basically this requires the valve to have a clearance to the housing no greater than 0.2 mm and have at least six vanes, so that two vanes are isolating the event at all times.

Many rotary valves manufacturers comply with these specifications.  When you are looking at a rotary valve for you combustible dust application, remember to confirm that the valve complies with NFPA-69. 

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

 

 

 

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Topics: dust collector, rotary valves, NFPA-69, combustible dust, deflagration

Aerodyne Environmental: Home of the Horizontal Cyclone and  Vacu-Valve® Airlock Valve

Inspired To Be Different.

At Aerodyne, we choose to take a different approach to collecting dust and handling materials. Our cyclones are unique in design to address common issues such as problematic dusts and space constraints. Our airlocks are chosen to fit your specific application instead of hastily installing traditional equipment options. We believe that when we see things differently, we can solve problems effectively. That's why so many people turn to us for help in solving their tough dust problems.

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