Food processors are experts at producing food products, chemical manufacturers are experts at developing chemicals, pharmaceutical companies are experts at making drugs, and pneumatic conveying manufacturers are experts at moving bulk solids. Just as it is not necessary to become an expert on how to build a vehicle when purchasing one, it is also not necessary for users of pneumatic conveyors to become experts at vacuum conveying to incorporate them into their processing line. While it is a good idea to have a broad understanding of how pneumatic conveying systems work, no pneumatic conveyor manufacturer will ever ask a customer if they need a dense phase or a dilute phase system. There are however a host of other questions a conveyor manufacturer will ask about a process, and the materials used in that process, that will aid them in designing a system with the necessary components to provide a solution that integrates into a customer’s process. 

Most people are familiar with how vacuum systems work because most have used some sort of vacuum system to clean their homes—put a pipe here, put a pipe there, suck it up and get on with the day.  Because of this familiarity, there is a common misconception that designing a vacuum conveying system is a matter of just connecting some components together.  While it is true that pneumatic conveying systems are simple in terms of their design, there is a world of difference between transferring bulk materials and sucking up dust from the living room floor; and, there is a distinct difference between conveying relatively unproblematic materials, such as plastic pellets or rice, and challenging powders such as iron oxide, zinc oxide, calcium carbonate, or toner.

When it comes to pneumatically conveying difficult powders, the difficulty does not lie so much with the conveying of materials through the material line because, generally speaking, once material is entrained in the line it is fluidized and moves freely.  Occasionally there are problems in the tube, even with free flowing materials.  When difficult material, Titanium Dioxide for instance, builds up in the line, agitator devices easily break materials free.

The primary challenge with conveying difficult powder is more commonly getting material to feed at a constant rate into the material line from the pick-up point and then again getting powder to discharge from the material receiver. 

For materials with poor flow properties that don’t want to move, extra attention is focused on  specially devised flow promotion devices, suitable filters and filter placement, and vacuum receiver design.  Proper vacuum pump selection is critical in any pneumatic conveying solution, and therefore does not necessarily stand out in this particular discussion of special equipment needed for difficult powders. 

Much like tuning a carburetor on a high performance race car, science can only go so far before testing and fine tuning are needed to bring about peak performance.  Designing and testing pneumatic conveying systems is much the same.  Even with 60 years of conveyor design experience, application knowledge, and two seemingly identical materials, testing is a necessary step to ensure the system will work as promised when installed in the client’s facility.  Pneumatic conveying manufacturers should always provide testing with user’s material at no charge. 

Cohesive and lightweight powders are prone to sticking and can cause choking and bridging.  Steady product flow into the material line and a proper solids to air ratio are critical with sticky materials.  If the solids to air ratio is too high, the line will plug and if it is too low, you are just sucking air and not transporting much material.  Feed devices assist getting material into the line at a constant rate. 

Feed Devices

The pick-up point is where material feeds into the tubing network that leads to the vacuum receiver.  The pick-up point could be a bulk bag unloader, bag dump station or wand that an operator inserts into a drum.  With difficult powders, specially designed flow promotion devices feed devices regulate flow.  These devices are most often some type of vibratory device but rotary or screw feeders are sometimes used where applicable.

Zinc Oxide and Iron Oxide are particularly nasty materials to convey due to their very poor flow properties—one could even liken them to conveying mud.  In one application, Iron Oxide was being transferred from 50 lb bags using a bag dump station to a mixer reactor.  With a bag dump station the operator places a bag on the shelf of the station, cuts the bag open, and the powder falls into collection hopper where it is vacuumed from the bottom of the collection hopper into the conveying line.  In this particular application the flow properties of the material was so bad that the material didn’t want to move from there.  To get product into the line, a specially devised live bin agitator, a hopper on rubber isolators with an oscillating vibrator that shakes the bin, facilitated material flow into a pick up adapter into the airflow stream. 

In addition, the bag dump station includes a unit that draws outside air inward to prevent dust from entering the environment around the operator.  In this case, the filters within that unit had to be suitable for zinc oxide.  Improper filters can become coated with dust, hindering airflow and choke the machine.  

Filters

The material of the filter, the number of filters, placement and cleaning cycle is extremely important for difficult materials.  At the top of the material receiver housing, filters separate the product from the clean air traveling back to the vacuum producer.  With ultra fine powders, filters can clog and choke the entire conveying process.

Carbon Black is an ultra fine powder, so fine that the running joke is that it gets into the wrinkles of your wrinkles.  In one application the task was recover residual Carbon Black out of the bottom of rail cars and discharge it into super sacks.  However, during the discharge cycle only 2-3 lbs would drop into the super sacks.  After testing with flow promotion, vibration and various other tricks of the trade, it was discovered that the material was getting hung up between the filter socks even with the automatic pulse filter cleaning.  The solution was to supply a new filter plate with fewer filters, but just as much filter area, to prevent the material from hanging up between the filters.

For applications where there is not enough space above the receiver, such as direct charge loader blending or low clearance areas, vacuum receivers without filters are available and the filters placed further down the line a safe distance from the vacuum pump.

Receiver Design

Angular surfaces provide areas where difficult materials can bridge or hang up.  Supplying a straight walled vacuum receiver eliminates sloped surfaces allowing positive discharge without requiring auxiliary vibration or agitation.  The straight wall configuration terminates in an automatic discharge valve the same size as the tube, permitting rapid passage of even the most difficult to handle non-free flowing material.

Ultimately, after all the science and spreadsheets, peak performance when pneumatically conveying difficult powders comes from fine tuning with a client’s material and knowing which components will move the material most gently, reducing wear and degradation.

            Celebrating its 60^th year designing and manufacturing innovative pneumatic conveyor systems and support equipment for the conveying, weighing, and batching of dry materials, Ahmedabad, India-based VAC-U-MAX is a pioneer with many industry firsts including air-powered venturi power units, direct-loading of vacuum-tolerant process equipment, and vertical-wall Tube Hopper material receivers.  The primary technology for conveying is vacuum, but positive pressure pneumatic systems, as well as mechanical conveyors, are also used as the specific applications dictate.  An equally important activity is the design and manufacture of heavy-duty industrial vacuum cleaners, which range from small air- and electric-powered drum-styled units to large electric- and diesel-powered units.

For more information about handling difficult or adhesive materials, or VAC-U-MAX pneumatic material handling or industrial vacuum cleaning solutions, write to us at info@vac-u-max.co.in

Every manufacturing process is unique and a multitude of factors come into play when designing a pneumatic conveying system, many of which are hidden from the greenhorn.  Although, two manufacturers might use the same material as one another, and even share some common equipment, factors unique to each manufacturing process will require tweaks distinctive to that process.  Even between twin plants, where equipment configuration is identical, factors such as humidity can alter the manner in which a system operates and slight adjustments may be necessary to ensure optimum performance.

Knowledge of material characteristics and a firm grasp of the fine points of pneumatic conveying can make or break a system that functions flawlessly 24/7 with minimal attention, which is what plant managers, maintenance managers, and engineers are seeking when considering implementing pneumatic conveying equipment. 

When it comes to pneumatically conveying difficult powders, the difficulty does not lie with conveying materials through the material line. Typically, once material is entrained in the line it is fluidized and moves freely. Occasionally there are problems in the tube even with free-flowing and difficult materials like Titanium Dioxide which build up in the line, with agitator devices easily breaking these materials free. The primary challenge with conveying difficult powder is getting the material to feed at a constant rate into the material line from the pick-up point and then again getting powder to discharge from the material receiver.  For materials with poor flow properties, extra attention is focused on specially devised flow promotion devices, suitable filters and filter placement, and vacuum receiver design. 

Feed Devices
The pick-up point is where material feeds into the tubing network that leads to the vacuum receiver. This could be a bulk bag unloader, bag dump station, or wand. With difficult powders like Zinc Oxide and Iron Oxide which have very poor flow properties, specially designed flow promotion feed devices regulate flow. These devices are most often a vibratory device or rotary screw discharger. In one application, Iron Oxide was transferred from 50 lb bags using a bag dump station to a mixer reactor. The flow properties of the material were very poor. To get product into the line, a specially devised live bin agitator, a hopper on rubber isolators with an oscillating vibrator that shakes the bin, facilitated material flow into a pickup adapter into the airflow stream.   

Filters
The material of the filter, the number of filters, placement, and cleaning cycle is extremely important for difficult materials. At the top of the material receiver housing, filters separate the product from the clean air traveling back to the vacuum producer.  With ultra-fine powders, filters can clog and choke the entire conveying process. In one application the task was to recover residual Carbon Black, an ultra-fine powder, out of the bottom of rail cars and discharge it into super sacks. During the discharge cycle only 2-3 lbs would drop into the super sacks. After testing flow promotion with vibration, it was discovered that the material was getting hung up between the filter socks even with the automatic pulse filter cleaning. The solution was to supply a new filter plate with fewer filters but with the same filter area. For applications with low headroom, such as direct charge blender loading, vacuum receivers without filters are available with filters placed further down the line. 

Receiver Design
Angular surfaces provide areas where difficult materials can bridge or hang up. Supplying a straight-walled vacuum receiver eliminates sloped surfaces allowing positive discharge without requiring auxiliary vibration or agitation. The straight-wall configuration terminates in an automatic discharge valve the same size as the tube, permitting rapid passage of even the most difficult to handle non-free flowing material. Peak performance comes from fine-tuning and knowing which components will move the material most gently, reducing wear and degradation. All equipment must complement each other. Vacuum receivers must be able to handle the airflow provided by the vacuum source and balancing the air-to-cloth ratio of filters must occur, so filters don’t shred or blind. 

Whether the application requires customized components or more economical plug-and-play solutions, pneumatic conveying solves safety hazards, production slowdowns, and material loss while moving product gently and quickly from point to point with nothing in the way to impede the efficiency of movement. 

In its draft Guidance Quality Considerations for Continuous Manufacturing: Guidance for Industry, the FDA stated that “adopting continuous manufacturing for pharmaceutical production will reduce drug product quality issues, lower manufacturing costs, and improve the availability of quality medicines to patients [1].” The widespread use and demonstrated success of vacuum conveying systems in many other industries that employ continuous manufacturing methods may have contributed to these expectations.
 
The Guidance defines continuous manufacturing (CM), as “an integrated process that consists of a series of two or more unit operations (the system) [2].” In such a process, “the input material(s) are continuously fed into and transformed within the process, and the processed output materials are continuously removed from the system [2].”
 
The definition of continuous systems in the Guidance also distinguishes between an end-to-end approach, where “the drug substance and the drug product process steps are fully integrated into a single continuous process and there is no isolated drug substance or intermediate,” and a hybrid approach where a “combination of batch and continuous process steps are used for drug substance or drug product manufacture [2].”
 
Vacuum conveying systems
A standard vacuum conveying system consists of five pieces of equipment that work as one: a pickup point, conveying line tubing, a vacuum receiver, a vacuum producer, and a control module.
 
The most basic vacuum conveying system is a timed system, consisting of two basic cycles: a conveying cycle and a discharge cycle. The control panel, which often works in concert with some type of level control, dictates the amount of time that the system conveys material to the vacuum receiver and then how long the discharge valves are open to drop the material into other equipment or intermediate vessels.
 
Vacuum conveying lines can be routed between floors, through partitions, and around machinery and can easily accommodate process modifications through rerouting.
 
Hybrid approach
Hybrid CM systems are often pre-engineered to be integrated with a specific unit operation, such as blending, mixing, tablet compression, capsule filling, or packaging. This makes the material handling continuous within a specific unit operation, but the unit operations themselves are still separate. Turnkey pre-engineered packages offer an affordable path to eliminate open handling and manual operations that can release fugitive dust into the environment. Fugitive dusts can negatively affect workers’ health, contaminate product, and pose combustible dust hazards.
 
End-to-end approach
In end-to-end CM, vacuum conveying equipment facilitates integration between unit operations, removing materials from one operation and feeding them to the next, using modern computerized technology with pneumatic design.
 
A fully customized vacuum conveying system completely integrates the system, where the discharge point from one unit becomes the pick-up point for the next. These types of sophisticated systems, which include multi-ingredient handling systems, are custom engineered to suit customers’ unique manufacturing processes.
 
FDA approval
Recognizing that manual material handling can have negative effects on drug product quality, the FDA redefined the types of manufacturing changes that need supplemental FDA approval, making it easier for drug manufacturers to adopt newer, automated technologies by simply requiring changes to be documented in annual reports. Appendix A of CMC Post-Approval Manufacturing Changes to be Documented in Annual Reports asserts that a “decrease in the number of open handling steps or manual operation procedures, when it reduces risk to product and there is no other change to the process [3]…” has “a minimal potential to have an adverse effect on product quality [4].”
 
The same ideal also appears in Scale Up and Post Approval Changes (SUPAC)-IR, indicating that, “(a) change from nonautomated or nonmechanical equipment to automated or mechanical equipment to move ingredients [5],” is a Level 1 change “unlikely to have any detectable impact on formulation quality and performance [6].”
 
These changes make it easier for drug manufacturers to automate processes with ready-to-operate pre-engineered vacuum conveyors for pharmaceutical applications such as softgel and capsule conveyors, tablet press loading conveyors, and direct-charge blender loading.
 
Whether you require a fully automated, customized system for CM or a general-duty or application-specific pre-engineered system, an experienced and knowledgeable vacuum conveying system supplier can help ensure that your equipment design aligns with FDA guidelines for pharmaceutical manufacture.
 
References
FDA draft Guidance. Quality Considerations for Continuous Manufacturing February 2019: Background, page 2.
FDA draft Guidance, Quality Considerations for Continuous Manufacturing February 2019: Definition of continuous manufacturing, page 22.
FDA Guidance, CMC Post-Approval Manufacturing Changes to be Documented in Annual Reports: Appendix A, section 3.6, page 9.
FDA Guidance, CMC Post-Approval Manufacturing Changes to be Documented in Annual Reports: Discussion, page 3.
FDA Guidance, Scale Up and Post Approval Changes (SUPAC)-IR: Immediate Release Solid Oral Dosage Forms Scale-Up and Postapproval Changes: Chemistry, Manufacturing, and Controls, In Vitro Dissolution Testing, and In Vivo Bioequivalence Documentation Manufacturing: Equipment, Level 1 Changes, Definition of Change, page 18.
FDA Guidance, Scale Up and Post Approval Changes (SUPAC)-IR: Immediate Release Solid Oral Dosage Forms Scale-Up and Postapproval Changes: Chemistry, Manufacturing, and Controls, In Vitro Dissolution Testing, and In Vivo Bioequivalence Documentation Manufacturing: Equipment, Level 1 Changes, Definition of Change, page 6.

Modern vacuum technology has been at the forefront of manufacturing technology since the beginning of the industrial revolution. From the first manually operated vacuum pumps of the late 1800s to the first industrial use air-powered vacuum cleaner in 1953, the first vacuum conveying system designed to deliver powders for ordnance in 1962, and current twin venturi technology, vacuum conveying is the most sophisticated method of handling powders and bulk solids today.

Vacuum conveying has always been used for plant efficiency, material protection, and safety, lending to its advancement and wide-spread use across most industries including pharmaceutical, chemical, food processing, additive manufacturing, and the aerospace industry.

Today’s vacuum conveying systems employ essentially the same concepts as the first systems of the 1950s, yet with more sophisticated components and advanced knowledge gained through practical experience.

Each industry poses different problems in terms of materials, regulations, and safety. Materials in the pharma and cosmetics industries utilize materials with particles so small you can barely feel them between your fingers; yet both industries have vastly different regulations, safety concerns, and quality control challenges. Other industries work with highly abrasive powders, hygroscopic materials, or utilize powders that are incredibly heavy at 250 to 350 pounds per cubic foot, like additive manufacturing.

Some applications with relatively unproblematic materials like sugar, plastic pellets, rice, and coffee are more straight-forward and may not need the level of engineering that challenging powders such as iron oxide, zinc oxide, calcium carbonate, or toner demand. However, even unproblematic powders can pose unique challenges, relative to process, that require custom engineered components. Likewise, some difficult powder applications may be suitable for turnkey off-the-shelf systems.

Why Vacuum Technology? 

As vast as material behavior is, so are the reasons why manufacturers employ vacuum technology. Some users want more automation, others are seeking to improve ergonomics or create a cleaner work environment, or manage materials cost; for others, increased throughput is the primary objective. 

Seasoned vacuum conveyor manufacturers translate information, passed down through time, between industries to engineer custom, semi-custom and off-the-shelf solutions that work on start-up.

Although the process of conveying the wax chips is straightforward, similar in nature to conveying plastic pellets, the melting point of wax poses challenges. Wax that melts at very low temperatures becomes sticky and adhesive requiring provisions to ensure the wax melts in the tank and not in the equipment being used to convey.

Vacuum Technology Applications

When International Converter, a division of Novolex, the leader in foil laminates, multi-web lamination, and specialty barrier and sealant coatings for use in a wide range of high barrier consumer and industrial applications, requested a quote for a vacuum conveying system to eliminate manual transport of wax chips to a raised platforms where workers dumped 40lb bags into a hopper, its ideal solution was a completely automated system that would allow it to change from using 40lb bags to super sacks.

There are numerous ways to engineer pneumatic conveying systems and previous experience with this type of arrangement, common across most industries, as well conveyor installations with other wax applications at Candle-Lite and JB Fuller, facilitated several design choices on the path to the final design that that met the customer’s ergonomic, production and financial needs.

Although all pneumatic conveying systems require some bit of human interaction, the first system iteration proposed the ideal solution to eliminate worker effort and risk, coming as close to a fully automated system as possible, complete with automated super sack unloading equipment and dual material receivers to facilitate the delivery of both gloss and matte wax beads to their respective tanks. The cost, however, was outside of what International Converter had to work with.

Although the automated bulk bag unloader would have further reduced worker interaction in the process, and therefore worker risk, it did not add much to the package otherwise. Had International Converter, which operates three shifts five days per week, wanted to increase throughput from its average of 1500 pounds of wax beads per shift, a bulk bag unloader would have been a more viable option.

Since the volume of pellets through the system was lower capacity, rather than using a bulk bag unloader, a wand was implemented as the pick-up point. Now, workers use a wand to suck material out of the super sac rather than suspending it. Though it is more labor-intensive than using a bulk unloader, using a wand to remove material from bulk vessels eliminates the exertion, repetitive motion, and awkward positions that occurred with manual handling of 40-pound bags, and has the same outcome as using a bulk bag unloader.

In addition to backing down the automation in the system design, instead of using two receivers to deliver both matte and gloss chips to the system, the facility’s high ceilings supported the use of a gravity diverter valve that acts like a splitter valve. The gravity diverter valve has a blade inside that switches from one direction to another, allowing the material to be diverted to the appropriate tank.

To ensure heat, rising from melting tanks, didn’t make the conveying equipment hot enough to melt the wax while conveying a Sparge Ring provided some isolation from the process to the conveying equipment. Sparge Rings are transition pieces with small fittings that create positive pressure and used most often with heat-sensitive equipment or vapor control.

Still, on a mezzanine level, the pellets are transferred, via wand, from a Gaylord up 20 feet to the receiver. Where it used to take two workers per shift and require equipment to be shut down while loading, a single person can do it, eliminating the risk, which was the primary goal.

While wax and plastic pellets are free-flowing materials, hygroscopic materials are not and tend to gum up and clog the system. Additionally, fugitive dust of hygroscopic materials, when released into the plant environment, makes housekeeping a time-consuming task.

Pneumatic Conveying System Replacement

When Ramsey, Delhi-based Company, producer of premium insulated wire and cable since 1878, needed a pneumatic conveying system for their SC plant, its goal was to replace its in-house system designed to reclaim super absorbent polymer (SAP) and control the environmental end of its proprietary process.

The proprietary three-step process coats wire cable with SAP. The SAP serves as a blocking agent so water cannot run inside the conductor if the cable or wire insulation system is breached in an underground or wet environment.

While the fine powder is very responsive to moisture and effective at protecting wires, and therefore systems from shorts, in production it is prone to gumming up with exposure to moisture. Exposure of SAP to the humid air alone can cause clumping affecting efficiency and productivity.

The process at one of the plant runs between 400 and 600 feet of cable per minute through a four-foot-long atomizer chamber that blows the SAP around in a cloud which coats the wires. The original system used a single filter housing to capture product for reuse; however, each time the filter needed cleaning, the chamber would switch from negative pressure to positive pressure and powder would escape into the plant atmosphere through the openings where the cable entered and exited the chamber.

Based on previous applications with hygroscopic materials, and SAP in particular, information about how much powder they were moving, the CFM, and the amount of powder wasted on overspray is what led to the design of a dual conveyor system with automatic changeover and a filter large enough to recover material.

Dual-Conveyor System

The dual conveyor system works essentially like that of a pumping heart. First, the cable enters a chamber at about 400-600 feet per minute while an atomizer simultaneously injects positive air and SAP into the chamber wherein it coats the cable fibers. At that same time, the dual conveyor system sucks the air out of the chamber at a faster rate than enters into the coating chamber, creating the negative pressure system wherein SAP cannot escape into the air external to the coating chamber.

From there, material enters the first of two valve chambers for a programmed amount of time. After that, the first valve closes while opening the second valve and chamber. When the first valve closes, air is blasted into the filter to release particulates to the bottom of the system where another routing system returns the SAP back into the hopper for reuse. This filtration cleaning process is repeated for a few seconds until the first filter is entirely clean, and then the second valve closes for its own identical process.

Where the company was losing about 7 percent of its material per shift with its original system, the dual conveyor system has brought loss to nearly zero.

In addition to the dual conveying system, a bag unloading station with enough negative pressure to remove the SAP before it has a chance to enter the air around the operator and plant environment further eradicates moisture from the system and reduces housekeeping.

Ready-to-Operate Systems

Automation does not always require complicated or custom-designed solutions. In many industries, even those with difficult powders like the pharmaceutical industry, long-term experience has led to the development of complete ready-to-operate systems.

Pharmaceutical materials tend to be very fine and prone to segregation, especially during manual transfer of materials in containers and from machine to machine throughout the production process. The vibration, caused by moving containers, promotes segregation, threatening batch quality. It is this reason that pharmaceutical manufacturers primarily use mass flow methods that move all particles at the same velocity, minimizing segregation.

Blenders, mixers and reactors are common types of equipment used in pharmaceutical processing facilities; and, just like many other types of equipment, require a mezzanine level for manual loading or specialized equipment like drum loaders or vacuum conveying equipment.

Although drum loaders are better than manual loading, limitations, such as the ability to load only one drum at a time, make the delivery of materials to the blender or reactor time-consuming. In some circumstances, it may also be necessary to load multiple ingredients into drums prior to loading blenders and reactors, further slowing the process by increasing processing steps.

Packaged Conveying Systems

One of the most efficient advances in loading blenders, mixers, reactors, or any vessel capable of withstanding vacuum, is packaged conveying systems designed specifically for the direct charge loading of blenders. With a drug processer’s blender or mixer as the primary receiver, the conveyor manufacturer provides the rest of the system: power source, filters, controls, and adapters.

Configured specifically to each application with standard equipment, direct charge blender loading systems come with the option of either floor standing, or suspended blender loaders designed to significantly reduce the amount of carryover, eliminating product loss and ensuring batch integrity.

Standing units are readily accessible for cleaning and can be equipped with casters, allowing them to service more than one blender. In addition, once the blender is loaded and equalized, carry over releases into an airtight vessel that preserves product integrity allowing for reuse or safe disposal.

With suspended units, once the blender is loaded and equalized, material automatically discharges back into the blender eliminating the need to handle product manually.

Because the units are easy to take apart without tools, clean up between batches and products takes only 30-45 minutes to wash down equipment and change out bags, filters, and hoses (when using different hoses for every product).

Summary

From fully automated custom systems to more economical plug and play solutions pneumatic conveying solves safety hazards, production slowdowns, and material loss while moving product gently and quickly from point to point, with nothing in the way to impede the efficiency of movement.

Celebrating its 65^th year of designing and manufacturing innovative pneumatic conveyor systems and support equipment for the conveying, weighing, and batching of dry materials, Ahmedabad-based VACUMAX is a pioneer with many industry firsts including air-powered venturi power units, direct-loading of vacuum-tolerant process equipment, and vertical-wall Tube Hopper material receivers. 

In an ongoing project to improve processes whenever and wherever it can, a global manufacturer of private label retail, foodservice, and specialty brand teas, purchased an extension conveyor system to improve efficiency and ergonomics.

Prior to implementing the extension conveyor, a vacuum conveyor system transferred raw materials into portable silos that workers rolled from one production machine to the next. Finished product was then transferred from silos to packaging machines using a VAC-U-MAX packaging vacuum conveyor.

The new extension conveyor system, from another vendor, transported raw materials from large bags that workers cut and introduced into the conveying line. Once in the conveying line, material moved through the production process and the finished product conveyed to mobile silos. The packaging conveyor, in use for 10 years, then transported the final product from mobile silos to packaging machines.

The tea manufacturer produces multiple grades of teas and the new extension conveyor system generated a higher volume of fine particles in the final product of its high-grade whole leaf tea products, resulting in a quality control issue.

Although the extension system vendor appropriately sized the system to gently move the whole leaf tea through the system, smaller particles (introduced into the system as result of breakage during transportation of raw materials from suppliers) further degraded while traveling through the extension system, creating a fine dust.

In addition, purging filters in vacuum conveying systems forces some dust back into the receivers and therefore the product, which in most industries isn’t an issue.

After unsuccessful attempts to remedy the problem with the vendor of the extension conveyor system, the tea producer contacted VAC-U-MAX for a solution.

After consultation, it was clear that the other vendor’s system wasn’t pulling off the fine dust the process was creating, so all entrained dust remained in the product and carried along the entire process.

The fine tea dust, up to 200 microns in size, is very receptive to static charge and was clinging to the inside of the cellophane packaging that wrapped around the boxes resulting in quality control issues and increased costs through lost product, cleaning times, and wasted production time.

The dust is just part of the product, but the company did not want to introduce it to the packaging machine because it makes cleaning and sanitation difficult.

The inherent nature of fully enclosed vacuum conveying systems prevents loose powder and dust from becoming airborne contributing to a cleaner and safer environment all around.

Vacuum conveying systems are fairly simple, consisting of five basic parts, a pick-point where material enters into the conveying system, convey tubing which transfers material between equipment, a vacuum receiver (typically equipped with a filter, and therefore often referred to as a filter receiver) which is an intermediate holding vessel for materials, a vacuum source that powers the system, and a control panel that tells the system how to operate.

In essence, larger more sophisticated vacuum conveyor systems that connect multiple processes consist of several conveying systems (without the need for multiple power sources or control systems) and therefore require multiple vacuum receivers.

Vacuum receivers are the second most modified component in a conveying system, after pick-up points, and are an integral part of conveyor performance.

When dealing with dust, system design requires interpretive consideration of multiple factors to reduce exposure and those factors change with each material, application, and process.

In industries where equipment is taken apart and cleaned on an hourly, daily, or weekly basis, like food and pharmaceutical processing, the use of filterless receivers, or cyclones (a specific design of filterless receiver that operates in a different manner), in combination with a filter separator can reduce housekeeping times, improve product quality, reduce the possibility of cross-contamination and help with allergen control.

The most common reason for including filterless cyclones in conjunction with filter separators is to eliminate the need to clean, maintain, and replace six or eight filters from receivers that sit above equipment. Filter separator is located remotely on the ground for easy cleaning and located away from areas where dust can pose problems.

In those types of situations, there is an extra unit sitting on the ground and each of the units on the silos have airlocks instead of filters. It can be done without the expense of additional equipment but there is still dust in the product, which for many industries is not an issue.

In fact, most companies want to minimize the amount of carry-over of materials, but this application required maximizing the amount of dust captured.

Carryover is the amount of product collected in the filter separator to separate the air from solids (dust) inside a vessel to prevent solids from reaching the vacuum pump.

The retrofit to the other vendors extension system included design principles similar to the 10-year old packaging system that uses two filterless receivers that share a common filter separator to pull off the fines–except for the magnitude of scale.

During the testing phase for the retrofit, the raw samples looked pretty clean before going through the system and the veteran conveyor experts knew that only full-scale testing could prove the reduction in fine particle dust. A visual inspection of the raw samples before conveying and the after samples showed a marked difference in how much nicer the end product looked.

After factory acceptance testing, a pre-engineered system arrived at the tea manufacturer with several retrofitted filter separators to integrate with the extension system to remotely maximize the amount of carry-over of tea dust drawn away from the extension system.

The retrofit eliminated 70-80 percent of the fine dust from the product and the customer gained throughput because there is better product going to the packaging machines, less clean up needed, and no wasted production time.

Enclosed vacuum conveyors prevent loose powder from becoming airborne. If a leak occurs in a vacuum conveying system, the leak will be inward preventing fugitive dust from escaping into the environment, making them the preferred method of transfer for sanitary environments where prevention of combustible dust conditions and cross-contamination is essential.

There are different threshholds of hygienic design based on specific industry guidelines required of food, pharmaceuticals, nutraceuticals, or cosmetics manufacturers. Although the FDA does not specifically address Hemp processing, the CBD extracted from it classifies as a drug and should follow pharmaceutical guidelines.

Sanitary and hygienic vacuum conveying systems have the same five basic components as standard conveying systems that come together to work as one – a pick up point, convey tubing, a vacuum receiver, a vacuum producer and a control module.

From the pick-up point, material flows through stainless steel convey tubes to the vacuum receiver which discharges powders through valves on the bottom of the receiver. The vacuum producer is the heart of pneumatic conveying systems and works with the control panel to manage the flow of material through the convey tubes to the vacuum filter receivers.

What makes sanitary vacuum conveyors unique is that all parts and components must be sanitary—meaning, easy to clean, and constructed with materials and fabrication techniques that meet Current Good Manufacturing Practices (cGMP). cGMPs for food and drug manufacturing specify general regulations for the design, construction, and fabrication of sanitary equipment.

In the realm of vacuum conveying, there are certain baseline standards that set the trajectory of building out a sanitary design system and every component must comply with the standards.

Filters, gaskets, vacuum hoses and valves, constructed of FDA-approved materials, should include certificates of conformance with project documentation.

While all components included in systems comply with FDA regulations, more sophisticated valves, such as rotary valves and butterfly valves, are specialty designs unique to sanitation. For instance, rotary valves incorporate slide-out rotors and wafer, or butterfly valves, feature split-valve construction for easy sanitizing.

Stainless steel convey tubing is the standard in sanitary design. In order to facilitate quick take apart design and support ergonomic standards, manufacturers design systems that limit convey tubing to 10-foot lengths (3000mm) which weigh approximately 50 pounds. The easy to take apart ferrules that connect the 10-foot sections comply with cGMP standards and require no tools and no loose parts for disassembly and re-assembly.

Surface finishes are important in sanitary design to limit places where materials or bacteria can cling to miniscule pockets. The surface finish of product contact surfaces in a sanitary design will involve some level of interior and exterior polishing and mandatory grinding down of welds. Most customers call for maximum roughness measurements of RA25-34, but the best sanitary design practices bring the roughness down to an RA between 10-15 as measured by a profilometer.

Continuous welds and sleeved holes in hollow members should be standard.

Well-designed sanitary conveying components include passivation after fabrication. Passivation with nitric or citric acid removes free iron from the surface of components providing a protective oxide layer that is less likely to allow moisture to stick to surfaces.

If there are any control elements located in a wash-down environment, stainless steel electrical enclosures are standard and have a water-shedding type of design with a sloped top, sloped door edges and rated for NEMA 4X.

While most processers establish engineering standards for sanitary design unique to their facility, product and sanitation process, they may lack the knowledge on how to most efficiently clean the equipment. Working with a seasoned conveyor manufacturer with decades of experience designing sanitary equipment with efficient design can significantly reduce cleaning downtime.

One of the most important factors in sanitary design is the ability to clean equipment thoroughly and quickly. Processors looking at purchasing sanitary equipment should know how easy it is to take apart and wash.

Vacuum conveyors are often permanently installed above other process machinery; and, therefore more time consuming to clean to the extent required for sanitary applications.

Mobile and column lift conveyors are complete conveying systems that raise and lower the receiver in order to load mixers, reactors, and other processing equipment and then bring the vacuum receivers back down to ground level for easy cleaning or sanitizing eliminating slip and fall hazards while cleaning. Mobile conveyors allow processors to move the equipment to another area for cleaning when necessary.

Clean-in-Place

Cleaning downtime can be devastating to a company—sometimes taking one to two days to tear everything down and clean it. When production throughput demands a high level of cleanliness with minimal labor and time, clean-in-place (CIP) equipment can eliminate hours of downtime.

CIP is a procedure designed to clean all or parts of a process system without needing to completely disassemble or move equipment. CIP is the strategic placement of spray balls, or nozzles, within vessels that circulate water and cleaning solutions. It is automatic and has consistent performance.

Although CIP has been around for a while, it is still a leading-edge technology, and is gaining traction in the food, pharma, nutraceutical, and cosmetics industries—so much so that the acronym is being used as a verb these days with customers saying they need “CIPable equipment.”

In CIP vacuum conveying systems, filter elements can be removed and replaced with insertable spray ball assemblies during cleaning. During the cleaning cycle, the pressure from the water or cleaning solutions extends the retractable balls outward for cleaning and then self-retract after the cleaning cycle, so they don’t interfere with the conveying process.

When a nutraceutical beverage producer landed a large contract, it needed to increase throughput and reduce the 8-hour cleaning cycle that occurred between batches in order to meet demand.

To achieve this, the beverage producer replaced its 90 cubic foot mixer with a 160 cubic foot CIP mixer, a CIP vacuum receiver, and CIP bag dump station. These changes reduced sanitation from 8 hours to 1.75 hours—gaining 6.25 hours of production and reduced labor costs every day.

The CIP system also averted the need to develop a confined space plan with the new larger equipment since the sanitation team didn’t need to enter the process vessel for cleaning.

Good sanitary vacuum conveyor design includes a package of simulated spray ball positioning and surface coverage documentation.

Time saving strategies

To save time some processors have two sets of convey lines and/or two sets of filters so they can quickly switch out dirty components with clean components, cleaning the other while the next process runs.

Other processors, particularly those that run different flavors or colors, might have filters dedicated to certain ingredients (like cherry or licorice for instance).

The practice of extra filters and tubing can be employed with CIP or traditional sanitary systems, increasing the speed at which processors get systems up and running again.

Sanitary design is a specialized field and expert conveyor manufacturers that have worked with over 10,000 materials and have decades of experience building hygienic vacuum conveyor systems understand the different requirements for food, beverage, pharmaceuticals, nutraceuticals, and cosmetic applications, and know what has to be done to provide processors with the most efficient sanitary powder and bulk solids transfer systems.

In an ongoing project to improve processes whenever and wherever it can, a global manufacturer of private label retail, foodservice, and specialty brand teas, purchased an extension conveyor system to improve efficiency and ergonomics.

Prior to implementing the extension conveyor, a vacuum conveyor system transferred raw materials into portable silos that workers rolled from one production machine to the next. The finished product was then transferred from silos to packaging machines using a VAC-U-MAX packaging vacuum conveyor.

The new extension conveyor system, from another vendor, transported raw materials from large bags that workers cut and introduced into the conveying line. Once in the conveying line, material moved through the production process and the finished product conveyed to mobile silos. The packaging conveyor, in use for 10 years, then transported the final product from mobile silos to packaging machines.

The tea manufacturer produces multiple grades of teas and the new extension conveyor system generated a higher volume of fine particles in the final product of its high-grade whole leaf tea products, resulting in a quality control issue.

Although the extension system vendor appropriately sized the system to gently move the whole leaf tea through the system, smaller particles (introduced into the system as a result of breakage during transportation of raw materials from suppliers) further degraded while traveling through the extension system, creating fine dust.

In addition, purging filters in vacuum conveying systems forces some dust back into the receivers and therefore the product, which in most industries isn’t an issue.  After unsuccessful attempts to remedy the problem with the vendor of the extension conveyor system, the tea producer contacted VAC-U-MAX for a solution. After consultation, it was clear that the other vendor’s system wasn’t pulling off the fine dust the process was creating, so all entrained dust remained in the product and carried along the entire process.

The fine tea dust, up to 200 microns in size, is very receptive to static charge and was clinging to the inside of the cellophane packaging that wrapped around the boxes resulting in quality control issues and increased costs through lost product, cleaning times, and wasted production time. The dust is just part of the product, but the company did not want to introduce it to the packaging machine because it makes cleaning and sanitation difficult. The inherent nature of fully enclosed vacuum conveying systems prevents loose powder and dust from becoming airborne contributing to a cleaner and safer environment all around.

Vacuum conveying systems are fairly simple, consisting of five basic parts, a pick-point where material enters into the conveying system, convey tubing which transfers material between equipment, a vacuum receiver (typically equipped with a filter, and therefore often referred to as a filter receiver) which is an intermediate holding vessel for materials, a vacuum source that powers the system, and a control panel that tells the system how to operate.

In essence, larger more sophisticated vacuum conveyor systems that connect multiple processes consist of several conveying systems (without the need for multiple power sources or control systems) and therefore require multiple vacuum receivers. Vacuum receivers are the second most modified component in a conveying system, after pick-up points, and are an integral part of conveyor performance.

When dealing with dust, system design requires interpretive consideration of multiple factors to reduce exposure and those factors change with each material, application, and process. In industries where equipment is taken apart and cleaned on an hourly, daily, or weekly basis, like food and pharmaceutical processing, the use of filterless receivers, or cyclones (a specific design of filterless receiver that operates in a different manner), in combination with a filter separator can reduce housekeeping times, improve product quality, reduce the possibility of cross-contamination and help with allergen control.

The most common reason for including filterless cyclones in conjunction with filter separators is to eliminate the need to clean, maintain and replace six or eight filters from receivers that sit above equipment. The filter separator is located remotely on the ground for easy cleaning and located away from areas where dust can pose problems.

In those types of situations, there is an extra unit sitting on the ground and each of the units on the silos have airlocks instead of filters. It can be done without the expense of additional equipment but there is still dust in the product, which for many industries is not an issue. In fact, most companies want to minimize the amount of carry-over of materials, but this application required maximizing the amount of dust captured. Carryover is the amount of product collected in the filter separator to separate the air from solids (dust) inside a vessel to prevent solids from reaching the vacuum pump.

The retrofit to the other vendor’s extension system included design principles similar to the 10-year old packaging system that uses two filterless receivers that share a common filter separator to pull off the fines–except for the magnitude of scale. During the testing phase for the retrofit, the raw samples looked pretty clean before going through the system and the veteran conveyor experts knew that only full-scale testing could prove the reduction in fine particle dust. A visual inspection of the raw samples before conveying and the after samples showed a marked difference in how much nicer the end product looked.

After factory acceptance testing, a pre-engineered system arrived at the tea manufacturer with several retrofitted filter separators to integrate with the extension system to remotely maximize the amount of carry-over of tea dust drawn away from the extension system. The retrofit eliminated 70-80 percent of the fine dust from the product and the customer gained throughput because there is the better product going to the packaging machines, less clean up needed, and no wasted production time.

To learn more about how VACUMAX’s pneumatic conveyors for food applications can improve efficiency, and ergonomics, preserve product integrity, or reduce costs, write to info@vacumax.in 

With over 34 years in the herbal supplement arena, Traditional Medicinals has combined the  ancient art of traditional formulating with the most modern scientific methods of quality assurance and production, and remains dedicated to preserving earth’s natural resources, both human and natural.

Already a leader in sustainability, operating 70 percent from solar power, the company continues its commitment to preserving human resources by continually improving the work environment for its employees, striving for the most desirable and safe workplace.

At the facility that operates 20 hours a day, four days per week to produce 2 million teabags per week, raw materials are brought in from around the world in already tea cut form, reinspected and repackaged into barrel containers to feed into the blenders via a hopper system.  Once the formulas are blended, they are transferred to the packaging area where they are gravity fed from a mezzanine level to IMA machines that process between 135 and 185 teabags per minute.

While working on a major efficiency project that culminated in the building of new rooms for the blending area Mary Goff, Plant Manager, says that the company also wanted “to cut down the amount of lifting that the operators were doing manually in our production department.”

Previously, the operators were weighing individual hundred pound batches into barrels, taking those barrels up to the top level, and then dumping them into hoppers manually by hand.  In search of a better method, the VP of Quality Control and the Site Manager researched open conveyor systems as an ergonomic solution for transferring the raw materials.

Traditional Medicinals uses pharmacopoeial grade herbs and one of its biggest concerns was how to transfer the herbs and blends from one area to another without breaking down the product or losing any of it.

“We did a lot of studies up front,” says Goff of choosing the right systems to transfer ingredients. “We spoke with some of our raw materials vendors about the systems they used to transfer materials and a gentleman from the consulting firm we were working with on the efficiency project told us about Vac-U-Max.”

A pioneer in vacuum pneumatic conveying, Belleville, NJ-based Vac-U-Max specializes in the design and manufacture of pneumatic systems and support equipment for the conveying, weighing, and batching of dry materials in the pharmaceutical, chemical, and food industries. 

Although the company’s herb suppliers warned against pneumatically conveying the herbs thinking that it would damage the ingredients, the information Traditional Medicinals pulled from the conveyor manufacturer’s website convinced the company the method was worthy of investigation.

Pneumatic conveying systems have many advantages over open conveying systems such as belt or bucket conveyors.   Ease of cleaning and the smaller footprint of pneumatic conveying systems are two of its biggest advantages. 

In addition, pneumatic conveying systems are fully enclosed, protecting materials from air, dirt and waste.  Because product does not escape from a pneumatic conveying system, particulates that can endanger or jam expensive equipment are prevented from entering the environment.

Although the advantages of the pneumatic system in theory seemed to outweigh the open systems, Traditional Medicinals needed assurance that the vacuum system would perform reliably without breaking down the product.