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Airlocks and Pneumatic Conveying

Airlocks and Pneumatic Conveying

by Dan Fried and Devon DeJong

Does your mind go straight to the scene of your favorite Syfy movie when someone mentions airlocks – where the hero (or villain) is trapped between safety and being sucked out into deep space at the press of a button? We like a good science fiction movie, too, but airlocks in pneumatic conveying get us just as excited!  

An airlock is a compartment with doors that can be sealed against pressure which permits the passage of people and objects between environments of differing pressure or atmospheric composition while minimizing the change of pressure in the adjoining spaces and mixing of environments. The airlock consists of a relatively small chamber with two airtight doors in series which do not open simultaneously. (Source) 

In pneumatic conveying, airlocks are the passageways that bulk materials use to move between environments consisting of different pressures, gases, or both, with the goal being to minimize pressure loss and to prevent the gases from mixing. (In pneumatic conveying, airlocks are used for passage between various environments of different materials like gases, or different pressures, or both, to minimize pressure loss or prevent the gases from mixing). Airlocks are a critical component of pneumatic conveying designs. When applied to conveying, the objective is to move bulk material across a pressure differential; low to high (Pressure Conveying) or high to low (Vacuum Conveying). 

How airlocks work can sound complex; however, the design is simple. When a product drops into a pocket on the top, the rotor spins and drops the product out the bottom. The rotor has VERY tight tolerances with the housing to prevent air or the product from blowing past the rotor tips. (A typical airlock will come with a rotor tip-to-housing clearance of between .004” and .007”; Once that clearance is above .0079″ it is no longer NFPA compliant). An airlock prevents air leakage across the pressure differential.

Airlocks Used in Bulk Material Handling

Drop-through airlock. What is beneficial about this airlock is that the cost is lower because it is more widely available. The downfall to the drop-through airlock is the head height. 

Drop-through airlock with rails. Customers appreciate this airlock because it is operator and maintenance-friendly. The drawback to this airlock is the cost on the application’s front end. 

Blow-through airlock. Compared to the drop-through airlock, the blow-through lock is preferred because of its head height and the feature that no pick-up shoe is needed. The blow-through airlock is avoided at times because of the cost and the few options it provides.

Airlocks and NFPA Compliance

Airlocks are one of the most important components of an equipment’s success. Knowing the application will determine whether the airlocks need to be NFPA Compliant.

The National Fire Protection Association is an organization that is devoted to eliminating death, injury, property, and economic loss due to fire, electrical and related hazards. The NFPA Codes & Standards states that the airlock has a minimum of 8 vanes. At least two vanes must always stay in contact with each side of the housing, and the vanes must be at least 3mm thick. This helps keep flames contained to the rotor pocket if there is an explosion. Plastic or rubber tips are not NFPA compliant, as they will not hold up to the heat of an explosion. It’s also important to know that rotor-to-housing clearance must stay below .0079″ (0.2mm).

SELECTING AN AIRLOCK

Many factors go into selecting the right airlock for a project. Knowing the environment to which the airlock will be exposed is a vital consideration.

  • Temperature is a key factor, so it is important to know if the airlock will be indoor or outdoor, and the temperature of the material being conveyed.
  • Pressure above or below the throughput needs makes a difference.
  • Product details surrounding the airlock need to be considered to select the proper airlock; i.e. bulk density, angle of repose, flowability, abrasiveness and explosiveness are all product characteristics that can affect the airlock.

When questioning which airlock is best suited for a project, consider the airlock itself; body type, body material, rotor style/material, inboard vs. outboard bearings, and gland vs. air purge shaft seal play into what airlock will perform the best.

There are many options to rotary airlocks.

  • The shallow pocket types reduce the volume per requirement and are generally used on filters, cyclones and silos.
  • A staggered pocket rotor has a continuous and uniform flow to provide a more accurate rate of material flow.
  • Fine Dosing rotors are beneficial when feeding or discharging fine powders, materials or granules that are contained in hoppers and silos.
  • A scalloped rotor is best suited for sticky materials or food-grade applications.
  • Flexible tip rotors are helpful when trying to avoid jams in the valve and are more suited for dust filters than food-grade applications.
  • Consider an adjustable rotor when handling more abrasive material.

Airlocks can also offer a variety of features.

A low-cost feature with a high reward is a shaft seal air purge. A shaft seal air purge will prevent material from entering the seals and bearings.

A Zero Speed Switch is a valuable feature where it alerts the system if the rotor stops spinning, jams, or breaks.

Although they have a high price point, Slider Rails allows access for cleaning and maintenance.

The material and the coating of an airlock is critical. Nickel plating, chrome plating, and tungsten coating all help prevent premature wear of the airlock. 

Factors, options, and features of airlocks can be overwhelming. Working with a skilled team of knowledgeable engineers in the field can help. With over 25 years of experience, HaF Equipment is that team Ready To Connect!

Summary:
HaF Equipment is here to assist you with which application would benefit from pneumatic conveying; and seeing is believing. So, contact a HaF account manager today to see what options we can provide you. 

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Pneumatic Blending – Back to the Basics

Pneumatic Blending

by: Jared Beaupre

Companies struggle with keeping their material handling equipment clean. especially the inside of the equipment.  For example, have you ever tried to clean an industrial-sized mixer, like a ribbon blender? With most industrial equipment, like mechanical mixers, it can be labor-intensive, and dangerous, to ensure the unit is effectively cleaned and that the backsides of all the mixing paddles are clean. The tiny crevices in the design are out of sight but not out of mind. But, what if we told you that you could blend your dry powders without a mechanical-oriented mixer? Imagine a blender that is just as clean and simple as an empty hopper and cone! At HaF Equipment, we have the solution: Pneumatic Blenders!

Using simple compressed air, a pneumatic blender pulses a bubble of air into the centerline of the cone. That air pushes a column of the dry material upward, like taking a core sample or cross-section of the stratified material. As the column of material moves upward, the air expands and accelerates to throw that material into the headspace of the hopper. It is this motion that creates the mixing action.

The motion of the material also creates an aeration effect that creates a fluidized state for the material. When in a fluidized state, the material is free-flowing. So, as that column of material lifts, the remaining material around the side walls freely flows down and replaces the material blown upward. The mixing of powders happens quickly, with no mechanical friction.

When Pneumatic Blending is Best

Pneumatic blending isn’t for all applications, however. It is best when an extremely quick and accurate blend is needed. Since the blending action isn’t a “folding over” or “mass cutting,” the blend is extremely homogenous in a very short period. Rather than a blend measured in tens of minutes, most pneumatic blends can be accomplished in less than a minute. All of this is, however, dependent on the material blended. Material that is easily fluidizable, such as flour, glass bubbles, or powders for ceramics, work extremely well. Materials that are large particles, such as stones or nuts, are not good candidates since the air tends to flow through the material, not allowing the column of material to lift.

Comparing Blender Types

  • RIBBON blender.

    A Ribbon Blender typically has a U-shaped horizontal trough and then a custom fabricated ribbon agitator that spins to mix powders. The pros to the ribbon blender are that it operates at a cost-effective price point and offers high capacity.  Pneumatic blending can also work with large tonnages.  Unfortunately, the ribbon blender does not fill all the way and is often left with dead space (unused space). Another downfall to the ribbon blender is that it can be dusty, especially around the mechanical seals.  Pneumatic blending is sealed tight and is a simple hopper in concept.  The ribbon blender also tends to have a larger footprint and can sometimes damage the product in production.  Pneumatic blending is essentially a simple hopper and cone with air pistons in the cone.  The pneumatic blender is gentle in regard to damaging product.  It uses compressed air, not stainless-steel agitators.

  • PADDLE blender. A mixing paddle blender uses a custom fabricated paddle, typically mounted on a shaft, which can be inserted on the shaft end into the end of a motor drive assembly.  The paddle blender offers large capacity, with reduced RPM. On the flip side, the paddle blender is not proven to be efficient, and the gearbox located on the top of the vessel can be a hindrance. 

  • TUMBLER or V blender.

    V blenders are rotary mixers, also called tumble blenders. Just like how it sounds, the shape of the machine is a “V”.  The V is formed by welding together two cylinders.  The whole unit rotates allowing the powders to mix.  This is called diffusive (or dispersion) mixing. In diffusive mixing, the particles of solids move randomly, typically rolling down when their container is rotated. The motion is driven by gravity and falling particles.  There is no mechanical agitator or ribbon.

    There are no agitators inside the V blender, all the movement of the powder comes from gravity and the rotation of the shell. Since there is no agitator, it will perform “ok” with free-flowing solids, but it is less effective with cohesive powders. 

    The benefit of the V blender is that is has smooth internal surfaces that results in a more sanitary design.  But this is the same with pneumatic blending where the inside of the vessel is sanitary smooth.

    You get the clean vessel with the pneumatic blender as needed in pharmaceuticals, and the pneumatic blender is ultra-sanitary. The tumble blender tends to be more expensive, offers low capacity, and does an “ok” job with mixing.

Pneumatic Blender

Pneumatic Blender Flexibility – Powders & Liquids

The applications and variations of the Pneumatic Blender are vast and can be used for varying applications depending on the industry. Coatings or flavor additions are a great way to use pneumatic blending with liquids.  Pneumatic blenders can also be used for fluidizing silos and aid in silo discharge of ingredient powders.

When the pneumatic blender is put at the bottom of a dense phase conveyor vessel, it can receive the powders in, blend, and dense phase convey the powders long distances.  This is extremely helpful when you want to blend powders in a powder dedicated room, and then send the blended batch of powders to a production line elsewhere in the manufacturing facility.  This set up is very flexible.

Lastly, this system can utilize inert gas to blend combustible powders.

Pneumatic Blender - HaF Equipment

Summary:
HaF Equipment is here to assist you with which application would benefit from pneumatic blending; and seeing is believing. So, contact a HaF account manager today to see what options we can provide to test the blender. We can do this in our facility with your material, or directly at your facility to give real-time results with as many in-plant conditions as possible. At HaF, we are Ready to Connect!

CONTACT US today to discuss your pneumatic blending equipment needs. 

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About HaF Equipment

HaF is a Minnesota-based company with employees spread out across the USA and capabilities world-wide. We’re ready to support your manufacturing industry needs no matter where you live or what type of industry – we’ve got our finger on the pulse Ready to Connect. 

For more information about how we can help you meet your goals, don’t hesitate to call us at (651) 653-5098, or complete the Contact Form on our website.

So, Who Wants to be an Engineering Intern?

Engineering Intern Opportunity

You have brains in your head. You have feet in your shoes. You can steer yourself in any direction you choose. You’re on your own. And you know what you know. And YOU are the who’ll decide where to go!

Every year, high school seniors face the question, “What do I want to do with my future?” Some people never decide on an educational path by the time they graduate and head off to college without knowing where their journey will take them next. Others are more focused than ever before – having every class picked out or at least knowing which ones might be right for them (and why).

Internships are a great way for college students to get real-world experience and learn about careers. They offer hands-on opportunities and help build networks with professionals, which can lead to opportunities later down a chosen career path!

"Being an Engineer Intern at HaF has allowed me to experience many different facets of engineering. I work daily with experts who love what they do and who facilitate my growth while we work as a team on real engineering projects. I've really enjoyed working at HaF and getting to know so many amazing people driven by a common goal."
Riley
current HaF intern and University of Minnesota Engineering freshman

Engineering Intern Opportunities at HaF

At HaF Equipment, we invite engineering students to intern with us and work alongside our experts in the field. Our internship opportunities allow students to be a part of real-world experiences, from building customer relationships, listening to business challenges, and walking through steps to develop a strategic plan and design a successful project.

HaF challenges each student to jump right in, embrace their role, and take ownership of their internship success. The true goal for our interns is for the experience to be more than “just an internship” but a pivotal step in their career path.

For more information or to apply for our internship opportunities visit the Careers page on our website.

Senior Engineer Intern

“HaF gives their interns real life experiences in projects that are critical to companies’ success. I gained incredible knowledge about the engineering world and have had the chance to apply my technical background in every project. Surrounded by an amazing team that is always ready to help has been an eye-opening experience.”

Resolved! Three Steps to Position Your Operations for Success

Positioned for Success in 2022

Webster’s Dictionary defines RESOLUTION as the act of finding an answer or solution to a conflict, or problem. It is the act of resolving something, an answer, or a solution to something. 

We all have something that comes to mind when we think about a personal resolution. However, have you also stepped back and reviewed your 5-year business plan and the current projects you are working on to see if they need an overhaul? Have you analyzed whether the steps you are taking today make your overall journey the most efficient? 

Successful companies pursue forward-thinking strategies to maintain their success into the future. Are your plans based on a volatile supply chain with nothing but uncertainty around it? Think beyond today and plan for unforeseen events in 2022. 

As technology advances, automation is becoming an integral part of operations, and success is finding that balance between it and humans. The current labor shortage has required companies to accommodate and innovate to respond to this problem. HaF Equipment has listened to the issues the manufacturing industry has faced and responded. We are at the forefront of the bulk material handling industry in designing, engineering, and developing innovations and automation to drive companies to their next level of success, and we welcome 2022 positioned for success.  

Positioned for Success in 2022

Steps to Success

HaF knows that every decision made today impacts tomorrow’s success, and we’re walking the same unknowns as you. However, we are committed to helping our clients make the best decisions for their future! Below we outline three steps to help.

 

  1. Stop. Stop for five minutes and answer these two questions – What’s Working? What’s Not? It is simple. Write down what works well in your operations, and then list what is not working.
  2. Contact. Contact HaF Equipment and let’s connect. We want to hear your answer to “What’s Not Working?”. Together, we will determine solutions to fill or eliminate weak spots and implement the solutions.
    • If equipment maintenance slows down production due to lack of parts, then set up your maintenance department with backup parts to prepare for the unexpected. Planning ahead will save time and potentially higher costs.
  3. In-Person Audit. Improve. Analyze your process
    • Is there a skip in the beat, and you’re not exactly sure where the problem is? We will perform an in person audit of your operations and our expert engineer will meet with you and develop a written report of best next steps, using industry best practices. Your steps today can lead to success tomorrow.

Successful companies pursue forward-thinking strategies to maintain their success into the future.

At HaF Equipment, we are constantly looking at the next phase of innovation. The success of our customers drives our success. Contact us today to discuss how we can help you welcome a successful 2022.

Keep It Clean: HaF’s Gravity Divert Valve

Gravity Divert Valve

HaF Equipment’s latest gravity divert valve is an ideal solution for those who need to upgrade their aging system with modern technology. This product will increase efficiency and help prevent expensive downtime due to inefficient and outdated systems. The gravity divert valve is built for sanitary applications and is fully accepted by the United States Department of Agriculture (USDA).

The focus for the gravity divert valve is on sanitary design and to provide an easy to clean divert valve positioned in the vertical orientation so that powder can flow and drop into either of two locations.

Using proven HaF design methods developed over 25 years, the gravity divert valve is part of our tool-free-quick-take-apart® designs developed for ease of cleaning. The main body can be disassembled and wiped down because there are no hidden crevices. The sanitary ferrule connections allow for a clamp to easily be removed, gaining access to clean the connections and easily remove the gravity divert valve for cleaning.

Gravity Divert Valve for article

Custom Gravity Divert Valve

Although the most recent Gravity Divert Valve that HaF configured has 6-inch diameter chutes, our team is innovative. HaF can design custom down chutes for whatever application the customer needs. Its framework is solid and is structured with a heavy-duty actuator. The valve has a “Y” Divert Split Configuration with a 60-degree offset. Precisely designed, the gravity divert valve is built with a dual coil solenoid and has a Proximity Limit Switch with a Cable.

Gravity Divert Valves are available in different sizes to mix and match components depending on the customer’s needs and specifications.

About HaF

HaF is a Minnesota-based company with employees spread out across the USA and capabilities world-wide. We’re ready to support your manufacturing industry needs no matter where you live or what type of industry – we’ve got our finger on the pulse Ready to Connect. 

For more information about how we can help you meet your goals, don’t hesitate to call us at (651) 653-5098, or complete the Contact Form on our website.

A Simple Way to Deliver Pre-weighed Batches to a Mixer: Dense Phase Conveyor Case Study

Dense Phase Conveyor

A great way to speed up your batch production is to add a gain-in-weight dense phase conveyor. A recent customer used HaF Equipment to pre-weigh powdered limestone under a silo.  The dense phase conveying vessel also served as a weigh hopper.  When the mixer called for a new batch, the dense phase vessel transferred the pre-weighed batch of material.

The great part of dense phase conveying is that the batch can send long distances!  No matter where you locate your mixer, the Gain-In-Weight Dense Phase Conveyor, can deliver, and do so very quickly!

Dense Phase Conveyor Case Study

About HaF Equipment

HaF is a Minnesota-based company with employees spread out across the USA and capabilities world-wide. We’re ready to support your manufacturing industry needs no matter where you live or what type of industry – we’ve got our finger on the pulse Ready to Connect. 

For more information about how we can help you meet your goals, don’t hesitate to call us at (651) 653-5098, or complete the Contact Form on our website.

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