Most Discussed Questions

A consistent theme at the booth was the challenge of feeding minor ingredients into batches efficiently and determining how hand loading can be automated. Attendees from production facilities approached the Hapman team looking for ways to streamline these processes, minimize manual labor, and improve the consistency of their batching operations. These conversations reflected a clear industry trend: bakeries and food processors are prioritizing automation and practical, hands-on solutions for ingredient management.

Showcased Products

Helix® Flexible Screw Conveyor

The Helix® drew the most attention at the show, serving as a true conversation starter and resource for attendees interested in batching and ingredient handling automation.

• Designed for versatility, the Helix® excels in transporting powders, granules, crystals, flakes, and pellets.
• Flexible tube and helical screw design allow horizontal conveying up to 80 feet and vertical discharge heights up to 40 feet, making it suitable for diverse facility layouts and batching requirements.

LP Low Profile Vacuum Conveyor

• Compact footprint that excels in tight, space-conscious bakery environments
• Conveys up to 90 cubic feet per hour, delivering performance without sacrificing valuable production space

Commitment to the Baking Industry

Hapman’s debut at IBIE 2025 highlighted more than just advanced equipment, it demonstrated a commitment to supporting bakeries with practical solutions that tackle everyday ingredient handling and process automation challenges.

With 80 years of experience, the Hapman team remains dedicated to helping customers drive productivity, enhance product quality, and maintain safety across any material handling application. For facilities facing their own batching or conveying challenges, Hapman invites industry professionals to connect and explore how tailored equipment and expert guidance can make a lasting impact on baking operations.

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A leading dairy cooperative in Ontario, Canada processes milk from its member farmers to produce butter, cheese, yogurt, milk powder, and other dairy products. These products are supplied to retail, food service, and industrial markets. To enhance product consistency and texture, the facility incorporates cellulose powder and plant fibers in its dairy formulations.

Understanding the Challenges of Conveying Cellulose Powder

Cellulose powder is a fine, fibrous material commonly used in food processing for its ability to improve texture and stability. However, its lightweight nature and tendency to generate dust create unique challenges in pneumatic conveying systems. The material’s low bulk density makes it prone to becoming airborne, increasing the risk of dust accumulation and explosion hazards. Additionally, cellulose powder is electrostatically charged, which can lead to material sticking to equipment surfaces, causing flow disruptions and maintenance concerns.

Moisture absorption is another key issue. As a hygroscopic material, cellulose powder can clump and build up inside conveying lines, potentially leading to blockages and inconsistent material flow. Because of these factors, effective dust containment, explosion protection, and careful material handling are critical for maintaining system efficiency and compliance with industry safety standards.

Customer Challenge: NFPA Compliance & Dust Containment

The facility had been relying on Hapman filter/receivers installed in 2010 as part of its pneumatic conveying system. However, evolving NFPA safety standards required an upgrade to improve dust containment and explosion mitigation. The customer needed a replacement solution that would integrate seamlessly into their existing vacuum conveying system while meeting the latest safety regulations.

Hapman’s Solution: E-Line Model 24R with Flameless Vent

To address the customer’s needs, Hapman supplied a Model 24R E-Line filter/receiver with a flameless vent. This unit was selected due to its compliance with current NFPA standards, ability to handle fine powder materials efficiently, and compatibility with the customer’s pneumatic conveyor system. Made of stainless steel with a food-grade finish, the E-Line unit ensures hygienic processing. If an explosion occurs, flames and dust discharge into the device and are extinguished as they pass through multiple layers of heat-absorbing stainless steel mesh, thus protecting the people and the equipment.

Why the Customer Chose Hapman

Proven Performance – The facility had successfully used Hapman equipment for over a decade.

Seamless Integration – The new unit fits into the existing process with minimal disruption.

Enhanced Safety – The flameless vent ensures compliance with modern NFPA standards for dust mitigation.

Results & Future Outlook

With this upgrade, the dairy cooperative will enhance workplace safety, improve dust containment, and ensure compliance with updated NFPA standards. By integrating a flameless vent, the system offers superior explosion protection while maintaining efficiency in pneumatic conveying. This investment supports the company’s long-term commitment to safe and effective bulk material handling.

Hapman continues to provide customized conveyor solutions for the food and dairy industry, delivering equipment that meets both regulatory requirements and operational efficiency goals.

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Key Features of Hapman Vacuum Conveyors

1. Regenerative Blower Technology: The core of Hapman’s Vacuum Conveyors is the regenerative blower technology. This innovative approach allows for effective material transport without relying on plant air, significantly reducing operational costs. By minimizing the need for external air sources, these conveyors offer a more sustainable and cost-efficient solution.
   
2. Reverse-Pulse Filter Cleaning System: The conveyors feature a reverse-pulse filter cleaning system, which ensures maximum filter efficiency and minimizes downtime. This system helps maintain optimal performance by keeping filters clean and functional, reducing the need for frequent maintenance.
   
3. Diverse Models for Specific Needs: Hapman offers three distinct models of Vacuum Conveyors, each tailored to meet specific operational requirements:

• MiniVac: Utilizes dilute phase vacuum technology, allowing for flexible installation and operation. The pipe can be routed around obstacles, making it ideal for complex layouts. MiniVac is available in painted carbon or stainless steel, offering durability and resistance to corrosion.
  • LP Series: Designed for tight spaces, this model is perfect for applications where space is limited.
  • E-Line: Emphasizes safety by protecting people and equipment from dust explosions. The E-Line is rated for pressures up to 14.5 psi, ensuring a secure environment for handling potentially hazardous materials.

Benefits of Hapman Vacuum Conveyors

• Enhanced Efficiency: By leveraging advanced technology, these conveyors optimize material movement, leading to increased productivity across various industries.
  
• Cost Savings: The use of regenerative blower technology reduces operational costs by minimizing the need for plant air.
  
• Flexibility and Safety: With models designed for different operational needs, Hapman Vacuum Conveyors offer flexibility and safety features that cater to diverse applications.

Conclusion

Hapman Vacuum Conveyors represent a significant advancement in bulk material handling, combining efficiency, versatility, and cost-effectiveness. With their advanced design and tailored models, these conveyors are poised to enhance productivity and efficiency across multiple sectors. Whether you’re looking to optimize material movement in tight spaces or ensure safety in hazardous environments, Hapman’s Vacuum Conveyors offer a reliable and innovative solution.

For more information on how Hapman Vacuum Conveyors can enhance your bulk material handling processes, visit our Vacuum page or contact our sales team at sales@hapman.com.

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A leading pharmaceutical manufacturer needed a vacuum conveying system to transfer finished product from a dryer to a mobile, scale-mounted bulk bag filler for precise batching. The primary challenge was ensuring complete cleanability to eliminate any risk of cross-contamination during product changeovers — a critical requirement in pharmaceutical processing.

Solution

Hapman engineered a Vacuum Conveyor equipped with individually controlled spray wash ports strategically located throughout the interior. This feature enabled automated, thorough cleaning and sanitization without external disassembly.
To further simplify maintenance, the system included a side access door for fast filter cartridge replacement and a clean-in-place rotary valve that could be disassembled, cleaned, and reassembled within minutes.
The entire sanitary assembly was built from 304 Stainless Steel with sealed motors and controls rated for explosive and wash-down environments, ensuring compliance with stringent pharmaceutical standards.

Results

The custom vacuum system met all performance and cleanliness requirements, enabling faster product changeovers, reduced downtime, and improved process efficiency while maintaining the highest standards of product purity.

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Understanding how dust forms, recognizing its potential hazards, and implementing effective control measures are essential steps in maintaining a safe and productive plant environment.

The Real Dangers of Industrial Dusting

Even a small accumulation of dust can present a hazard in processing environments. The Occupational Safety and Health Administration (OSHA) may cite facilities for combustible dust hazards under the General Duty Clause (Section 5(a)(1)), which requires employers to maintain a workplace free from recognized dangers.

While OSHA does not define a specific dust depth limit, it references NFPA guidelines suggesting that dust layers thicker than 1/32 inch (about the thickness of a paper clip) covering more than 5% of a room’s surface area can pose a significant explosion risk. This includes dust on beams, joists, ducts, and equipment surfaces.

The National Fire Protection Association (NFPA) recently consolidated several combustible dust standards into NFPA 660: Standard for Combustible Dusts (2024). This unified standard replaces NFPA 654 and provides updated guidance for preventing fires and explosions related to combustible particulate solids. It also emphasizes reducing secondary dust explosions, which are often responsible for the most severe damage and injuries.

In addition to explosion risks, uncontrolled dust can:

• Create slip-and-fall hazards on coated surfaces.
• Impair visibility in work areas.
• Increase respiratory health risks for employees.

The message is clear: effective dust control is critical to ensuring safety, compliance, and reliable operations.

How Hapman Helps You Control Dust at the Source

The most effective way to minimize dust is to control it where it originates. Hapman offers a range of engineered dust mitigation solutions designed to capture and contain material before it becomes airborne.

Conveyors

Hapman’s Tubular Drag, Flexible Screw, and Vacuum conveyors feature sealed designs that confine materials throughout transport. When paired with dust hoods or collection systems at inlet and discharge points, these conveyors significantly reduce airborne dust and improve overall plant cleanliness.

Central Dust Collection Systems

Central dust collection systems are highly effective for large-scale processes, capturing and removing dust from the plant environment. However, they are typically best suited for extensive operations since they remove material from the process stream and can be more costly for smaller applications.

Point-of-Use Dust Collectors

Point-of-use dust collectors capture particulates directly at the source—where dust is most likely to form. Common applications include:

• Bag dumping stations for 20–50 lb. ingredient bags.
• Bulk bag unloaders handling 2,000-lb. bags.

These systems use cartridge filters and timed pulse-cleaning valves to return captured material to the process. By keeping dust localized and contained, they help maintain cleaner air, safer work conditions, and greater material efficiency.

A Smarter Approach to Safety and Profitability

Effective dust control is about more than compliance—it’s about creating a safer, more efficient operation. With Hapman’s engineered solutions, processors can reduce airborne dust, protect employees, and maintain consistent productivity across every shift.

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By Steve Grant, Product Specialist

Pneumatic conveying systems are frequently an excellent choice for moving large quantities of powdered, granulated or pelletized material. And among the many different approaches to pneumatic conveying, regenerative blower-driven vacuum systems can provide ideal cost effciencies, compactness and simplicity where vacuum requirements and transfer distances are modest.

Many other types of pneumatic conveying systems like pressure-driven systems are designed for moving heavier materials over longer distances; they require fairly robust pressure, large capital equipment investments, more operating energy and higher maintenance costs. Downscaling this kind of pressure-driven technology to meet the needs of smaller-volume, shorter-distance transfer isn’t always a practical or economical approach. Fortunately, regenerative blower-driven vacuum systems like those produced by Hapman give processors the right combination of design and operating characteristics for excellent economics in lighter-duty situations.

Operating principles of vacuum conveying systems

Vacuum conveyors are relatively simple systems that include a pick-up inlet, a conveying tubing line, a receiver and a vacuum generator, which is the power source. The vacuum generator creates the required negative pressure to pull the material through the conveying line and into the receiver. Internal filters separate the material from the air to remove any dust and protect the vacuum generator. A number of different gating systems may be used for removal of product from the receiver, including simple sliding valves, pneumatically-operated dump gates or air lock rotary valves.

Power source options for vacuum systems include regenerative blowers, compressed air driven eductor (venturi) units, plant central vacuum using liquid ring vacuum pumps or low-pressure blowers or positive displacement vacuum pumps. With the exception of regenerative blowers, all of these vacuum power sources are external to the conveying equipment itself.

Vacuum systems are preferred for transporting materials that tend to pack or plug in a pressure system. And they are excellent choices where space is at a premium. With many lightweight materials, their conveying velocities can be quite high, between 3,600 and 5,000 feet per minute. One notable limitation is reach; they’re not typically used for conveying distances above 200 feet, or where vertical distances are above about 50 feet.

Integral vacuum generator

Unlike almost any other pneumatic conveying technology, regenerative blower equipped conveying systems like Hapman’s are unique in that the vacuum generator is integral to the system; no external plant air or vacuum is required.

The regenerative blowers that power these systems are very simple and reliable. They have few parts, just an electric motor with sealed bearings, an impeller and a housing with a cover. There are no other moving parts or wear parts that require lubrication of maintenance.

Inner workings of a regenerative blower

Regenerative blowers work on a vortex air flow principle. Air is effectively moved between vanes as a single-stage impeller rotates in a casing. The spinning impeller and air flow create a vortex flow pattern which boosts velocity incrementally as the air moves from vane to vane inside the housing. The flow of air on the output side is very steady and smooth. Product lines like Hapman’s include blowers from 1.5 to 15 hp, which can supply suffcient vacuum for material conveying capacities up to 18,000 lb./hour.

Advantages of Stand-Alone Regenerative Blower Vacuum Conveying Systems

Lower initial costs – Regenerative blower vacuum conveying systems are self-contained, requiring only an electric power hookup. There’s no requirement for air or vacuum supply runs, or for internal studies of available capacity utilization. For facilities without plant air or vacuum supply already in place, operators avoid the expense of planning, installing and maintaining these external vacuum power systems.

Lower operating costs – Compared to externallypowered pneumatic conveying systems, onboard regenerative blower systems offer considerably higher energy effciency, typically twice that of conventional air compressor-driven systems. Maintenance costs are also much lower, especially when compared to external air compressors or positive displacement (PD) blowers, where ongoing maintenance items include lubrication and replacement or maintenance of filters, belts, regulators, coolers, muffers and plant air lines.

No competition for plant air or vacuum – These self-contained systems place no additional demand on plant air systems. It’s an advantage in terms of overall capacity planning and swing capacity availability for other users in the facility during peak demand periods.

Easy to install – Regenerative blower vacuum systems weigh less and take up less space than other pneumatic conveying systems. They’re easier to transport into manufacturing environments, and they’re simpler to install.

Easy to clean – For routine filter cleaning, regenerative blower systems like Hapman’s are designed for easy filter element access without tools. Where there’s a need for overall system cleaning, regenerative blower systems are available with provisions for central unit and tubing washdowns.

Oil-free air – Regenerative blowers don’t require internal lubrication, so they produce oil-free air.

Low noise – Noise levels for these systems are very low compared to other air or vacuum supply systems.

Comparisons to Other Air/Vacuum Supply Technologies

Table 1 provides a useful comparison of regenerative systems to two alternatives, positive displacement and air compressor technologies, that are sometimes used in similar applications.

Case Studies: Real-World Solutions to Production Challenges

Automating Material Handling System Improves Worker Safety, Economics and Production Rates

Werner G. Smith, an Ohio-based chemical manufacturer, was awarded a long-term contract for a new customer to blend a granular powder with an aqueous chemical solution. Werner was able to dedicate a large reactor to the contract manufacturing process, but the building housing the reactor presented serious logistics issues. There was no loading dock, and to get the operation up and running quickly, Werner initially relied on a team of five employees to manually carry 55 lb. bags of material into the building and up one story where an operator would manually dump material into the reactor. In the course of a week’s production the team had to handle over 800 55 lb. bags of material.

Said Jennifer Bugbee, Vice President of Operations at Werner G. Smith, “This was an enormous waste of time and manpower, and we needed to streamline the process, reduce powder hazards and reduce strain on the workforce.” Through a local industrial equipment supplier, Werner connected with Hapman.

Hapman designed a material handling system that included a Loss-in-Weight Bulk Bag Unloader that feeds a Hapman Vacuum Conveying System that delivers material to process. The vacuum conveyor system includes an integral regenerative vacuum blower, integral filtration, a reverse pulse filter cleaning mechanism and automated batch controls.

The returns for Werner G. Smith were almost immediate. Production time improved by several hours per batch, and facility housekeeping improved dramatically. The system also eliminated the need for a third-party vendor to break down and repackage material into 55 lb. bags so Werner employees could manually handle them. The five employees were assigned to duties more directly related to production.

Vacuum Conveying System Eliminates Cross-Contamination for Pharmaceutical Company

A major pharmaceutical company came to Hapman with a need for a vacuum conveyor system to take their finished product from a dryer and discharge it into a mobile bulk material handling system, which was scale mounted for precision metering and batching. The challenge was that it needed to incorporate an efficient cleaning system to eliminate any possibility of cross-contamination with product change overs.

Hapman engineered a pneumatic vacuum conveying system with individually controlled spray wash ports placed throughout the interior of this material handling conveyor. This self-contained design allowed the customer the ability to reliably clean and sanitize the conveyor’s interior without the need for time-consuming external procedures. Further time saving enhancements included a side access door for quick filter cartridge change outs, and a cleanin- place rotary valve which allowed disassembly, cleaning and reassembly within minutes. The entire sanitary finish assembly was 304 stainless steel with sealed motors and controls rated for explosive atmosphere and wash down applications.

The completed system delivered on all design goals. Effciency and processing rates were subsequently increased.

Conclusion: The Ideal Choice for Modest Production Requirements

Regenerative blower-driven vacuum conveying systems certainly aren’t for every application. They aren’t a viable alternative to the more powerful systems needed for longer transfer distances and heavier materials. But as described here, they deliver an outstanding suite of advantages for smaller, shorter-run conveying systems that operate at lower vacuum or air consumption rates. Their effciency, simplicity of operation, small footprint and low maintenance requirements mean they can deliver a unique combination of economics and practicality.

Advantages of Pneumatic Conveying

Whether pressure- or vacuum-powered, pneumatic conveying systems offer processors many advantages, including:

• Simple; essentially tubing, receiver and vacuum source
• Fully enclosed, no dusting, contamination, ignition spark generation
• No large, heavy conveyors with numerous wear parts and maintenance
• Good-to-excellent energy-effciency
• Can run horizontally and vertically
• Quiet

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Choosing a Pneumatic Conveying System: Pressure or Vacuum

Because they are efficient and inherently dust-tight, pneumatic conveying systems provide the most practical method for moving large quantities of dry materials, whether powdered, granulated, or pelletized. Pneumatic conveyor systems, which use an air stream to move materials through horizontal and/or vertical piping, come in two forms: pressure or vacuum.

The Differences and Similarities in Pneumatic Conveyors

Pneumatic conveyors can utilize either a pressure system that introduces compressed air at the system inlet in order to push the material through the piping or a vacuum at the delivery end in order to pull the material through the piping. Pressure and vacuum systems can be used for dense (high pressure/ low velocity) or dilute (low pressure/high velocity) phase operation.

Dense phase conveying systems have a low air-to-material ratio. Velocities are below the saltation level, the critical velocity at which particles fall from suspension in the pipe. Dense phase systems, therefore, move the material through the piping in batches, with discrete dunes or plugs of material separated by pockets of air. Valving systems can be adjusted to reduce the air pockets.

Dillute phase conveying systems have a high air-tomaterial ratio. In this type of system, the material is most often fluidized, or suspended in the air flow, and moves at relatively high velocities depending on the particle size and density. Dilute phase systems usually deliver the material continuously. Material is constantly supplied at the pickup point and is conveyed to the receiver without interruption.

Pressure Systems

The basic components of a pressure system are a rotary air lock feeder valve, a high pressure air compressor system or a low-pressure positive displacement blower or fan to serve as the power source. A pressure vessel, the conveying line, and the receiver make-up the balance of the system. Systems using high-pressure compressed air, operate with pressures above 15 psig, usually with a beginning pressure of about 45 psig and an ending pressure near atmospheric pressure. Low-pressure displacement blowers or fans supply a beginning pressure below 15 psig and an ending pressure near atmospheric pressure.

First, the materials is charged into the pressure vessel through the rotary air lock. Once the pressure vessel is filled, the inlet and vent valves close and seal, and highpressure air is gradually introduced into the pressure vessel. The high-pressure air conveys the material to the receiver, where the air and the material are separated by a filter or other system. Valves and sensors control the air pressures and velocities. When the predetermined low pressure setting is reached at the end of the conveying cycle, the air supply is turned off and the residual air volume purges the pressure vessel and the conveying line.

Pressure pneumatic conveying systems are generally preferable when transporting heavier materials longer distances. Pressure pneumatic conveyors can be fairly costly, however, since they require special equipment, like a rotary valve to introduce material into the air stream at the inlet and extra components to remove the air at the discharge end through a vent system.

Vacuum Systems

The basic components of a vacuum conveyor system are the pick-up nozzle, the conveying line, the receiver, and the vacuum generator, which is the power source. The vacuum generator creates the required negative pressure to pull the material through the conveying line and into the receiver. A number of devices, including a regenerative blower, a compressed air driven eductor (Venturi) unit, a plant central vacuum using liquid ring vacuum pumps or low-pressure blowers, or a positive displacement vacuum pump, can serve as the vacuum generator. The maximum negative pressure generated and the overall capability of the system, as well as the system efficiency and general operating characteristics, are determined by the type of vacuum generator used.

The air flow created by the vacuum generator moves the material through the conveying piping and into the receiver. There, gravity causes the material to drop into the receiver hopper. Internal filters separate the material from the air to remove any dust and protect the vacuum generator. Delivery of the material from the receiver to its final destination (e.g., process vessels or a packaging line) may be accomplished using a number of methods dependent on application suitability, including a dumpgate simple slide valves, pneumatically operated dump gates, or air lock rotary valves.

Vacuum conveying systems are usually preferred for transporting materials that may tend to pack or plug in a pressure system. They are also a good choice when space is at a premium; for example, attaching a pressure system rotary valve in the limited space below a hopper rail car may be impractical. However, vacuum conveyors are not a good option if you need to transport materials long distances. Because they operate with pressures at or below atmospheric pressure (14.7 psig), vacuum conveyors are limited to a maximum horizontal distance of 50 feet and a maximum horizontal distance of 200 feet. The effective horizontal distance is also reduced by vertical distances and piping bends.

Which Pneumatic Conveyor Best Suits Your Needs?

You will want to consult with one or more pneumatic conveying system specialists before making your decision. However, you should prepare for your discussion by answering the following questions:

• What kind of material is being transported through the pneumatic conveyor? Is material or piping degradation a concern?
• What is the purpose of transferring your materials in a pneumatic conveying system? Do you simply want to move material? Do you want to transfer more material than your current system can handle? Are you more concerned with reliability and efficiency, or gentleness of transport?

To answer these questions, you need to consider a number of material handling characteristics, including conveyability, optimum air-to-material ratios, buildup tendencies, flowability, and degradation. Figure 1 provides some guidelines to assist you in choosing the right system for the material you need to convey.

Pneumatic Conveying Systems Summary

Pneumatic conveying systems, whether pressure or vacuum, are an excellent choice for providing efficient and dust-free conveying. And while pressure systems are preferred for conveying heavier materials longer distances, vacuum systems are the conveyor of choice for materials that have a tendency to pack or where physical space within the plant is limited. Because of the seemingly limitless variability in system requirements and diverse material bulk densities, designing an optimized system must first begin with identifying these elements with a qualified conveying expert. Taking into account the physical needs of the plant environment, the availability of plant air, and characteristics of the materials being conveyed will ensure that your pneumatic conveying system is the best, most efficient and economical choice for your current and future needs.

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CHALLENGE

A major pharmaceutical company came to Hapman for assistance in providing them with a vacuum conveyor system to meet their specific requirements. It was to take their finished product from a dryer and discharge it into a mobile bulk material handling system, which was scale mounted for precision metering and batching. The problem was that it needed to incorporate an efficient cleaning system which totally eliminated any possibility of cross-contamination with product change overs.

SOLUTION

Hapman engineered its pneumatic vacuum conveying system with individually controlled spray wash ports placed throughout the interior of this material handling conveyor. This self-contained design allowed the customer the ability to reliably clean and sanitize the conveyor’s interior without the need for timely external procedures. Further time saving enhancements included a side access door for quick filter cartridge change outs, and a clean-in-place rotary valve which allowed disassembly, cleaning and reassembly within minutes. The entire sanitary finish assembly was 304 stainless steel with sealed motors and controls rated for explosive atmosphere and wash down applications.

RESULT

All of the companies requirements were met – their efficiency and processing rates were subsequently increased.

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Deliver measured amounts of four powdered ingredients, received in bulk bags to slurry tanks. Some materials are hygroscopic, flow poorly in humid environments and may contain small agglomerations. Whereas some materials do not mix readily into solution, the delivery must be metered so as not to exceed the mixers ability to force it into suspension. System must be automatic and fit into an existing manufacturing space with a very limited footprint. Housekeeping is a concern- provision to minimize the escape of airborne product is essential. Control system must be open architecture and comprised of commonly available, highly dependable components to minimize downtime.

IMPROVEMENTS WITH AN AUTOMATED APPROACH

The Hapman solution involved four extended height bulk bag unloaders which allowed vertical integration of various components, each aimed at addressing a specific need while making the most efficient use of available space. The hoist and trolley mechanism first moves the bags into position. The access chamber (untie box) includes an integrally filtered dust collector (see image below) which maintains ambient air quality while enabling the captured particulate to remain within the system so as to avoid generation of a separate waste stream and lost product. Pneumatically actuated bag agitators fluidize the material and cause it to flow freely from the bulk bag and through a lump breaker which continuously breaks up incidental agglomerations. The free flowing, conditioned material is then delivered to a PosiPortion loss-in-weight screw feeder to precisely measure the amount of product and regulate the rate at which it is delivered. Finally, a pneumatic conveyor was used to transfer the rate controlled batches and a system of diverters directed the batch to the appropriate slurry tank.

POSITIVE RETURNS

Hapman provided a system that addresses all material handling challenges, while consuming the least amount of available floor space. Metered delivery of powders assures efficient downstream mixing to optimize overall process performance. User friendly controls and monitoring equipment minimizes operator interface time, freeing plant personnel to address other process concerns.

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Based on the above specifications, the flexibility of an eductor system proved beneficial for several reasons. An eductor type mixing system can be used on a batch or continuous basis. A continuous process can control the concentration based on outside requirements, such as pH, conductivity, flow, pressure, temperature, and rate of reaction.

A batch system can also be adjusted from one batch to another varying the concentration of the solution or slurry (see Figure 2). The bulk bag unloader was included in the system and put on load cells to correctly measure how much material was delivered over time. To help EP Minerals design an optimal system for their application, Hapman first established a materials rate to determine the most efficient size for the feeder and the eductor. The bulk density of the diatomaceous earth was stated as 16 lbs/ ft3. The rate was determined to 22 ft3/hr to successfully achieve a concentration of 7.15%. The following steps were used to determine feeder and eductor size:

1. Determine the feed rate required (22 ft3/ hr) and select the feed rate, (see Table 1).
2. Select the maximum discharge pressure required (5 psig). NOTE: Using the standard educator, the maximum pressure drop allowed is 5 psig.
3. If the feed rate is in excess of 24 ft3/ hr, or the maximum discharge pressure is not acceptable, then find the appropriate multiplier and divide that multiplier by the actual rate, (see Table 2).
4. Use the multiplier to find the required liquid flow rate.

The data from the EP Minerals application is shown in tables 1-3. The selected eductor is 1”, to meet a feed rate of 10 gpm, with a not-to-exceed 5 psig back pressure on the discharge of the eductor. Because of the abrasiveness of diatomaceous earth, stainless steel construction was selected for the system.

Next, the auger size of the feeder was determined, based on feed/dosing rate, (see Table 3.). An appropriate nozzle was then selected to match the screw.

The final step was to determine if the system should be controlled by volume or by weight. Because of the application’s need for accuracy, a weight-based system was selected. Though more expensive and complex than standard volumetric controls, a weight-based system allows for ± 0.5% accuracy. A volumetric control has an accuracy margin of between ± 2% to 5%, and would not have worked with this application’s process specifications.

SUMMARY

This case study demonstrates how an eductor-based mixing system can effectively handle a wide range of materials, and how overall process optimization can be achieved. In addition, the eductor mixing system offers increased efficiencies over a conventional system of mixing by allowing solutions and slurries to be made on demand – as opposed to pre-mixed in large holding tanks. Another important benefit is the system limits exposure to operators, and mitigates issues of delivering solid material in a large vapor space.

The design flexibility of an educator-based mixing system offers a high level of customized configurations. This allows process design engineers the opportunity to efficiently and effectively meet the demands of a facility’s many different raw material handling needs.

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