VIBCO Vibrators offers affordable, effective and reliable air cannons to suit many industrial or construction applications. hopper that gives mass flow with one powder may give core flow with another. (USP 1-May-2024) Changes in flow rate as the container empties can also be. It may lead to injury and hazardous plant environments, and compromise product safety. Valves & Actuators. Ratholing, and Poor Material Flow . 31+0. Figure 1: Manufacturing pharmaceutical tablets and capsules involves several powder handling steps. Flow agents are used to enhance the flow behavior of solids by reducing the inter-particle adhesion force. There are many consequences of flow problems. 4. In ratholing, a vertical flow channel develops above the hopper outlet and, once emptied, remains stable. Ratholing definition: Present participle of rathole . 2. their manufacture are in powder form. When bulk solids build up into an arch or dome-like shape over the hopper’s outlet and block the flow, it’s called arching or bridging. Some of these conditions include:. These behaviours are related to the cohesive strength of the powder, which is a function of the applied consolidation pressure. • Easy to clean due to detachable components. It is critical to understand the type of hang-up that you may be experiencing. Arching and Ratholing does not occur. An arching flow p Figure 3. Ratholing: can occur in a bin when the powder empties through a central flow channel, but the material at the bin walls remains stagnant and leaves an empty hole (rathole) through the material, starting at the bin outlet (Fig. Ratholing occurs when only a flow channel located above an outlet discharges product. In this study, we showed that the major principal stress (σ1) at the bin outlet is required for. Where less desirable properties are present, poor powder flow can: lead to challenges during blending (no discharge or ratholing), 4 difficulties when discharging the powder into the hopper 5 or issues regarding weight uniformity in the tablet. The purposes of this investigation were to develop a method to evaluate flow properties of powders from avalanching tests and to detect similarities and relationships between these data and conventional powder flow properties. Powder-container design affects discharge rate, cleanability, and powder flow. In a silo, hopper or bin, the powder is exposed to various pressure. Mass flow eliminates ratholing and maximizes the pers with planar geometries (e. Occurs for small outlet size =< 6-10 * max particle size (D 90 ) b. Some products like dry cell battery. Minor powder flow issues during R&D can turn into major headaches once scale-up to production begins. : Fine Powder Flow Phenomena in Bins, Hoppers and Processing Vessels. Our pneumatic and electric chute and pipe vibrators and vibratory equipment will: Unload dry or semi dry bulk material. Pumps, Motors & Drives. Segregation Ratholing (Fig. Solimar Fluidisers create twice as much aeration action as many lookalikes. Valves & Actuators. 3. Powder Rheology. Buildup in the Silo is an Indication of Ratholing. They all have one thing in common: none will predict whether or not a powder will flow in a hopper. 0”. Equipment for powdered metals, ceramic powders, pigments, chemicals, super-abrasives. You would think after all these years that our industry would realize that there is a scientific approach to solids handling and therefore silo design. 2. Our pneumatic and electric bin and hopper vibrators will: Promote the consistent and controlled material flow of dry or semi-dry bulk materials. flow channel empties, flow stoppages will occur when powder along the walls remains stagnant. Ratholing is a flow obstruction is a no-flow condition obstruction that can cause erratic that prevents material discharge discharge from a bin, as well as from a bin. 1. Larger particles are more likely to penetrate the surface than fine particles. 1016/0009-2509 (96)00250-3. In practice, this group of bulk materials is the most common. 2 pcf Spring Back Index (SBI) 1. include modifying the hopper, adding a bin insert, using a flow. :4167–4181. Tired of hammering on equipment, engineers thus began the development of flow aids for bulk solids. 10a or M-cell that is. These problems lead to losses worth thousands of dollars at. Motor with gear suitable for running at 30 rpm. Comparison of the flow properties of eight commercial dairy powders5. The unique design can feed sticky, fluffy, lumpy, flaky, and fibrous materials without issues of bridging and ratholing in the hopper. The advantages for handling powders and bulk solids via fluidization instead of traditional deaerated gravity flow include: Elimination or reduction of arching (bridging) or ratholing problems Powder Cone Valve System. On the other hand, NP0 produced mass flow behaviour even for the narrowest orifice diameter of 2 mm. 93+0. Figure 10. This creates a non-flow regime whereby a discharge aid is needed to re-initiate powder flow from the silo. The key to feeding cohesive materials in a screw feeder is with the use of Flow Aids. the powder flows at the place of the smallest flow resistance. A superb discharge device, it overcomes all the typical powder handling and flow problems of bridging, blockages, mix segregation, flushing and core flow that are commonly associated with butterfly valves. When the flow channel empties and material flow ceases, it can form a stable rathole that may collapse and block the opening. Typical powder flow issues found in the hopper are ratholing, bridging, and segregation. Problems associated with ratholing are flooding, substantial variation of density in product, and eventually no-flow. • Prevent ratholing, bridging and damage to the material. Magnetism is often overlooked for metal powders. 2. Predicting powder flow behavior is important to successful solids-handling processes. Lack of discharge in theFlow-rate limitation and flooding: problems specific to fine powders. Ratholing occurs when material in the center discharges completely while material nearer the walls of the hopper. Process Control & Automation. Powder flow obstruction during hopper/bin discharge, such as arching or ratholing, remains an outstanding risk and cannot be reliably diagnosed using the existing flow function coefficient-based method. Basic silo shapes: a conical; b wedge-shaped; c asymmetric wedge-shaped; d. Hoppers. A key variable that will have an impact on the flow is its cohesive strength. This can disrupt your production line. The simplest way of explaining the flow function is with the uniaxial unconfined failure test shown in Figure 4, which measures the. The most common and serious problem is no-flow, due to arching or ratholing [6], [7]. Why are my powders are not flowing efficiently?Ratholing occurs when discharge takes place only in a flow channel located above the outlet. For example, testing on a Flodex™ may show that a neat API powder has flowability of 26 mm, with a round tabletDischarge of powder from a hopper or bin is a common operation in solid dosage form manufacture. was used to control the flow of powder. Once the central flow channel has emptied, all flow from the silo stops. Geometry modifications are. Jenike, who pioneered the theory of bulk solids flow at the University of Utah in Salt. Erratic flow results when ratholes collapse, causing the powder to arch as it impacts the out-let. As the silo empties, side material flows into the middle channel. The flow channel drains material in the middle first. Robert Sedlock. Bridges of powder can form in your containers preventing flow. More than 70% of all products contain ingredients that are handled in bulk solid form at some point during the production process. Avoid silo problems, such as bridging, funnel flow, ratholing, arching, segregation and product decay. May be formed by 1. This article describes a study scientists conducted to resolve a powder-binding problem that developed during the scale-up—from proof-of-concept scale to pilot. Ratholes develop most often in conical hoppers that are not steep enough to produce flow at the walls. 3. Aside from funnel flow, powder bridging is another undesirable flow issue which can occur in the hopper (Fig. Bridging is the inverse of ratholing—instead of a void, a bridge of material forms and refuses to flow or move. Powder flow can also vary from lot-to-lot, which needs to be understood during R&D. 46+0. Options for explosion proof and pneumatic vibrators for hazardous. Mixing & Blending. Jenike shear testing has determined the following. The flow of powder out of a silo is stopping primarily for 2 reasons ; either formation of arches (arching, bridging) or ratholes. This was attributed to the fact that the poor flowability of APAP could cause ratholing and high flow variations, especially when the powder. "ratholing" can occur, that is, the diameter at which. Matcon designs and manufactures powder handling equipment that can be used to improve manufacturing processes across a range of applications. 2002). The corresponding control schemes at different levels for the feeding-blending system are provided in Table 6. a cohesive arch when particles bond together ii. include arching (when the powder forms a cohesive bridge over the outlet) and ratholing (when the powder flows out only from the. Why Battery Manufacturers Choose the Circle Feeder. Test results allow a formulator to determine required hopper outlet dimensions that will prevent flow stoppages, hopper angles necessary to prevent ratholing, and outlet sizes required to achieve. Schematic representations of challenges arising on the storage (ratholing during silo storage - a), handling (build up on powder conveying line - b) and applications of high-protein dairy powders requiring rehydration (powder clumping. m. , will present "Solids Flow Properties That Affect Your Feeder Design" as part. This occurs when particles are conveyed in the gas stream at a velocity that is less than the saltation velocity. Ratholing: can occur in a bin when the powder empties through a central flow channel, but the material at the bin walls remains stagnant and leaves an empty hole (“rathole”) through the material, starting at the bin outlet (Figure 28. Because of this flow pattern, funnel flow silos that are not emptied. UK-based powder flow solutions firm Freeman Technology offers this video on how particulate materials react when aerated, loosely packed or. ) but it. Powder Mix Segregation. Flow occurs in most powder-based processes, opposed by various cohesive forces. rathole, bridging and segregation to occur. Santos et al. Powder flow obstruction during hopper/bin discharge, such as arching or ratholing, remains an outstanding risk and cannot be reliably diagnosed using the existing flow function coefficient-based method. The training set Y data included the observed flow patterns of mass flow, funnel flow, ratholing, and bridging (4. Ratholing occurs when discharge takes place only in a flow channel located above the outlet. 5). They are most often used in storage bins and chutes to promote flow of stored material, but they can also be used in continuous flow process vessels and. Unload and produce good faster in your production process. How to prevent ratholingAuthors: Dietmar Schulze. The API AeroFlow® automated flowability analyzer was tested using 6 pharmaceutical excipients. W. Silos and hoppers are particularly prone to this issue if the. a more practical non-invasive method to visualize dynamic powder flow is needed that can help to quantify the efficacy of a given unit operation (such as in silos/bins) used in. Ratholing. 26. A better approach to predicting flow behavior is to take the characteristics of wall friction (φ w ). Two modes of flow can result in dense phase, namely piston/plug flow and. Arching, ratholing, caking, segregation and flooding are some of the commonly encountered flow problems in the handling of fine powders. Leading Powder Handling Equipment. 9b, although the variation of the blend flow was larger compared to the total powder flow in case study 1. Ratholing occurs when discharge takes place only in a flow channel located above the outlet. the powder blend exhibit ‘Funnel Flow’. If the coarser particles stick to the sides of the hopper they can get rancid and contaminate the next batch. 3. Referring now to another embodiment shown in FIGS. Figure 3: Stagnant, cohesive powders can form a stable rathole in funnel flow. Flow problems related to food powders, such as arching, ratholing and erratic flow are thoroughly described and reviewed by Marinelli (2005). Powder bridging occurs when the pressure actually locks the powder granuals together because they simply can not pass though the neck of the case and pressure increases dramatically. critical pressure at the abutment of the dome ê $) in hopper design principles, is the stress that facilitates powder flow Pharmaceutical powder discharge from a hopper Buildup in the silo is an indication of ratholing and potentially asymmetric flow, which can increase pressure loads inside silo walls. Powder has a natural ability to move and fall when it is stored in a silo or a hopper. Differences in densities and flow rate cause the materials to separate on a vibrating conveyor belt, upon free-fall into a bin, or when flowing horizontally into a container. Material Flow Solutions, Inc. Ratholing: can occur in a bin when the powder empties through a central flow channel, but the material at the bin walls remains stagnant and leaves an empty hole (rathole) through the material, starting at the bin outlet (Fig. Learn in this page what are the root causes of both arches and ratholes and how to avoid them. Solution: Reduce Movement. Includes supplementary material: sn. An extreme case of funnel flow is referred to as “ratholing”. Many of these flow issues can be traced back to improper discharger or feeder designs. 25”; vibrator with 2. Kozicki and Mehos found that when potash powder was agglomerated. The core flow pattern can also be described as funnel flow where mainly the core is in movement and the powder pattern resembles that of a funnel. Thus, it will not be separated. This method may be used for all powders, dairy and non-dairy products. g = gravity constant. 5D Bunker: A shallow bin, where H < 1. Powder Hand Process 4:293–299. The depth of the trough into which the powder is filled is 12 mm and. The goal of the design process is the determination of the hopper wall inclination necessary for mass flow and the minimum outlet size to prevent flow problems due to arching or ratholing. powder flow is uncontrolled due to randomly collapsing of rathole (Royal and Carson. The design of a silo is based on the most economical case: gravity flow. Why are my powders are not flowing efficiently? In ratholing, a vertical flow channel develops above the hopper outlet and, once emptied, remains stable. forms. Bulk solids problems such as bridging, ratholing and demixing are proactively prevented. Its unique construction fulfills allows for quantitative dosing steadily and evenly. For example, a Flodex may show a neat API powder has flowability of 26mm, with a round tablet design of 12mm in diameter. Funnel flow silos are usually more cost effective to construct, costing between 20-30% less than mass flow silos, but are not suitable for all materials. Schulze RST which is equipped with either S-cell that is shown in fig. The gyrators also reduce particle segregation to make sure each bag is completely. Bridges of powder can form in your containers preventing flow. flowsonic supports the flow of powders in silos, pipes, feeders, conveyors and other bulk material handling applications. Of course the outlet of the hopper has to be large enough to prevent bridging above the feeder. If the object is to maintain material flow only, fewer vibrators may be used. powder addition easier. Fluidization is commonly used with pulverized fuel handling, drying operations, reaction processes, and fine powder hopper discharge systems. Roller compaction is often used in solid dosage manufacturing because the resulting granules have better flow properties than the original powder for tableting or capsule filling. m. Discharge of powder from a hopper or bin is a common operation in solid dosage form manufacture. 327. "Rotoflo is the best silo discharger!Ratholing can occur when coal flow takes place in a channel located above the silo, bunker or hopper outlet. . No flow due to arching or ratholing. All figures are courtesy of the authors. The bin activator works discharges not over the full covered area, but only in a small unpredictable area and coarse ratholing. Discharge of powder from a hopper or bin is a common operation in solid dosage form manufacture. Assessment and predictive modeling of pharmaceutical powder flow behavior in small-scale hoppersForty years ago, Jenike [Gravity Flow of Bulk Solids, Bulletin 108, Utah Engineering Station, 1961] and Johanson [Flow Indices in the Prediction of Powder Behavior, Pharmaceutical Manufacturing. Test results allow a formulator to determine required hopper outlet dimensions that will prevent flow stoppages, hopper angles necessary to prevent ratholing, and outlet sizes required to achieve. The solid dosage form (tablets and capsules) is manufactured by either dry-blending of fine powder ingredients or combining the ingredients in a wet granulation step, followed by drying. Figure 1: Manufacturing pharmaceutical tablets and capsules involves several powder handling steps. Even high viscous material can be fed through the feeder and discharger smoothly. Caking of powder can have adverse effects on solubility, mixing, and dispersion resulting in loss of products, delays in launch and consumer complaints. Before. 59 2 Effective Angle Intl Friction 53. Check out this expert article on Powder Handling in Encapsulation from Right Stuff Equipment, experts in solid dose processing & packaging machinery. When you have buildup in the silo, the loads associated with asymmetric flow can be detrimental to the structural integrity of the silo as they can lead to wall failure and total silo failure. aid, modifying the feeder, or using gas injection. The simple cure is to use Ball powder. Frequently powders that are deemed easy flowing exhibit flow problems such as bridging, ratholing, or erratic discharge. Senior Consultant responsible for developing Engineering. to 11 a. The reason for this is that when a result in a flooding condition at the outlet. Hopper and feeder design is critical to ensuring proper material flow when handling and storing powders and bulk solid materials. A mass flow screw feeder prevents preferential flow which can lead to ratholing and arching problems. Sometimes, slow mixing paddles can keep bridging and ratholes under control. Chem Eng Sci. Discharge of powder from a hopper or bin is a common operation in solid dosage form manufacture. Dimensions to Prevent Arching: Mass Flow Bin. 4. Most problems that manifest on the. Silo Blending / Segregation 3. Problems of powder flow a. Section 1 Arching and Ratholing Dimensions of the Flow Report indicates the arching and ratholing dimensions of your material as a function of time at rest, temperature, etc, as follows: Arching Dimensions Time at Rest, hours -- In our example, the material was tested to simulate 0 hours storage (continuous flow) or as if the material was put. Scope. Keep in mind that the mass-flow bin design process is iterative. One of the recommended types of flow aids is called Mechanical Agitation. Bulk solids and powder flow properties testing is considered mandatory when designing screw conveyors and screw feeders for handling difficult to manage products. Purutyan H. It is a superb discharging device overcoming all manner of powder flow problems. Powder flow obstruction during hopper/bin discharge, such as arching or ratholing, remains an outstanding risk and cannot be reliably diagnosed using the existing flow function coefficient-based method. Mass flow develops when all the material in a silo is in motion whenever any is withdrawn. Since funnel flow will result in a first-in, last-out flow sequence, any side-to-side segregation that occurred when the equipment was filled will often be exacerbated 7. The flow of powder out of a silo is stopping primarily for 2 reasons ; either formation of arches. Also in the case of funnel flow, asymmetry is of no help when ratholing has to be avoided. The powder's flow pattern has a major effect on the development of certain flow problems, especially flooding. As a general rule, extremely fine powders (<200 mesh) deaerate and pack readily (dusts, talc, etc. The principles discussed in this chapter can be applied to analyzing new or existing equipment designs. 2. Another method to improve flow is. Absolute flow factor: FLA = FLR * ρb0. When your bottom line depends on moving product efficiently through your plant, obstructions in the flow of material can bring profitability to a complete stop. This can lead to problems like buildup on the interior of tubes or vessels, or “ratholing” or “bridging” of product in hoppers. Bulk solids and powders frequently encounter various flow challenges, including bridging, ratholing, flooding, and inadequate flow rates, and more. 2000 - Present 23 years. Ratholing is influenced by the bin/hopper geometry and outlet size the material is fed through. 2. 0 feet Ratholing Index (RI) 10. A Mass Flow Approach to Solving Your Sifting Segregation Issues Using a mass flow pattern will not only prevent the flow problems typically experienced by funnel flow (ratholing, flushing, etc. Ratholing. 770-255-1322. Posted by Control Concepts USA on September 13, 2022 7:13 pm. Ratholing is influenced by the bin/hopper geometry and outlet size the material is fed through. These are examples of material flow problems. AirSweep breaks up material blocks and sweeps the vessel walls clean. What Can Cause A. Conducting studies throughout R&D and scale-up can help identify and isolate where in the process a formulation issue began. 2. (Powder and Bulk Solids) (regular, part-time and distance learning) • PhD (Powder. 1 Importance of powder flow in the pharmaceutical industry 6 1. View our Flow Solutions Video! One of the most common problems with bulk material flow is a condition known as ratholing. Wall Thickness of 0. Discharge of powder from a hopper or bin is a common operation in solid dosage form manufacture. 24hr Emergency Service. Traditional powder testing methods cannot force the bridging to occur in a repeatable manner and thus they cannot discriminate flow differences between powders. With. 4704, or Email Us. Flow obstructions occur when the forces opposing motion exceed the forces promoting. The Circle Feeder can be used as a material feeder, large industrial feeder, laboratory feeder, powder. Issues covered in the segment include ratholing, arching (bridging), erratic flow, flushing, and more. Whether powder will flow smoothly or in an erratic manner inside a bin or a hopper depends on the flow pattern inside that equipment. c. Hey Guys! Today I'm going to show you how to replace a bad cv joint (Constant Velocity Joint) step by step. Prevent segregation with mass flow. 3’ diameter opening is required to collapse a rathole, even at this low head. 1. The reason for this is that when a result in a flooding condition at the outlet. Predicting powder flow behavior is important to successful solids-handling processes. When your bottom line depends on moving product efficiently through your plant, obstructions. Getting the powder flow wrong can be highly disruptive to plant performance and productivity, particularly where equipment has to be taken off-line and stripped down for cleaning out blockages. In addition to potential ratholing, powders, like cement or flour, can become aerated when filling a bin and, if the silo is not designed with sufficient retention time for the material to become deaerated by the time it reaches the outlet, it will flow out of the silo uncontrollably, like. Preventing Arching and Ratholing. Eastern/11 a. It offers automatic and controlled discharge of virtually any powder type, winning where other systems have failed. Pumps, Motors & Drives. Prevent bridging and ratholing. Material Flow Solutions engineers offer scientifically-based solutions for your powder flow issues. doi: 10. Depending on the flow properties, these materials are difficult to handle. In most cases, the vessel or bin can be attached to a vibrator, which shakes the vessel to pack the powder together. The silo influences the powder via the silo diameter, height and the angle of the hopper. Motors & Drives Valves & Actuators Powder & Bulk Solids. Ratholing occurs when material in the center discharges completely while material nearer the walls of the hopper remains in place. Some of the most challenging. A proven and practical scientific approach for designing bins and feeders based on a material’s flow properties. The powder flowability is defined as the ability of a material in the form of particles to flow in a desired manner when used in specific equipment [33]. Powder flow obstruction during hopper/bin discharge, such as arching or ratholing, remains an outstanding risk and cannot be reliably diagnosed using the existing flow function coefficient-based method. 4 Flow FactorsArching, ratholing, caking, segregation and flooding are some of the commonly encountered flow problems in the handling of fine powders. pharmaceutical tablets, detergents, ceramics, powder metallurgy etc. Eliminate bridging, rat holes, stuck material and uneven flow in chutes and pipes. to compare flow on a Flodex™ powder flow tester (Teledyne Hanson Research, CA, US) with the tablet configuration to determine whether the powder’s intrinsic flow is close or equivalent to the cross-section of the tablet press die. Ratholing synonyms, Ratholing pronunciation, Ratholing translation, English dictionary definition of Ratholing. g. Definitions: Bin: Any upright container for storing bulk solids. In addition, poor flowability can also cause content uniformity concern because of insufficient mixing. ) (Ganesh et al. a. Hoppers designed for mass flow with high-quality surface finishes can address these issues. 456 inches. Eliminate bridging, rat holes, and stuck material. If the material being handled is cohesive, the material outside of this channel will not flow into it and may cake or agglomerate. 26. Ratholing is influenced by the bin/hopper geometry and outlet size the material is fed through. The hopper design plays a role in this as hoppers with sharp angles and rough surfaces can inhibit powder flow. Due to the cohesive strength of fine dry fly ash, the material is a great source of friction. Air displacement as the product flows from the container can cause segregation, leading to an inconsistent end product. Calculating the hopper wall angle is and the critical outlet diameter is critical in preventing arches from forming and if you want the powder to flow. Storage Silos 101. To overcome bridging the wall friction must be reduced or prevented from occurring. The hopper design plays a role in this as hoppers with sharp angles and rough surfaces can inhibit powder flow. downtime and degraded product quality. Robert Sedlock. flow, including ratholing, erratic flow, flood-ing and segregation. Mass flow is the ideal flow pattern where all powder moves downwards towards the opening, and is often recommended by powder consultants for consistent and reliable flow. Mass-flow bin. Figure 2: The two primary flow patterns that occur in gravity discharge are funnel flow and mass flow. Check drier is switched on. Pivotal work on the development of the theory of bulk solids flow began in earnest in the early 1950s, when. Powder flow obstruction during hopper/bin discharge, such as arching or ratholing, remains an outstanding risk and cannot be reliably diagnosed using the existing flow function coefficient-based method. Powder flow obstruction during hopper/bin discharge, such as arching or ratholing, remains an outstanding risk and cannot be reliably diagnosed using the existing flow function coefficient-based method. Powder is moist. Air Cannons For Solving Tough Material Flow Problems. The primary measure of powder flowability is the powder flow function - which gives a measure of the amount of strength the material retains at a stress free surface following consolidation to a given stress level. , “Increase Powder. This method may be used for all powders, dairy and non-dairy products. It offers automatic and controlled discharge of virtually any powder type, winning where other systems. Apparatus. As a general rule, extremely fine powders (<200 mesh) deaerate and pack readily (dusts, talc, etc. . Material Flow Solutions, Inc. Flow difficulties at the blending step often manifest as slow/no discharge or ratholing. Materials interlock or bond together to form an arch above the outlet, blocking any flow. Addressing Powder Flow and Segregation Concerns during Scale-Up of Nutraceutical Solid Formulations . We Resolve Storage Structure Ratholing. Define Ratholing. The system is designed to help prevent powder bridging and ratholing in silos and hoppers. The Wolfenbuttel, Germany) is used for measuring the flow properties of bulk solids or powder ( fig. /d. LIW feeder flow rates can be compromised when the sudden change of the powder weight (e. Ratholing occurs when material empties out through a flow channel above an outlet. Various powder flow properties, such as cohesion, unconfined yield strength,. Flow function test. The reason for this is that when a powder becomes deaerated in the stagnant region of a funnel flow bin, it usually develops Flow function is only half of the solution because it’s a measure of powder cohesiveness: Powder flows if: Ì % = σ1/ffc The external stress arising from gravity, (a. Schulze RST which is equipped with either S-cell that is shown in fig. Ratholing occurs then there is excess build up on the walls of a storage structure, so much so that there is a thin and restricted passageway for materials to flow down the vessel. When the flow channel empties and material flow ceases, it can form a stable rathole that may collapse and block the opening. The flow properties of a bulk solid can have a significant impact on process efficiency and the success of the end product. , which have the potential to cause work stoppages [3]. the types of flow problems that can occur and the flow patterns. The powder influences the silo by the flowability of powder causing bridging and ratholing. The flow properties that govern whether a powder is prone to ratholing include cohesive strength, wall fric-tion, and bulk density [1-5]. 2 Flowability indicators used in industries 7 1. capacity — as low as only 10–20% of the bin’s rated stor- age capacity. • Stable and strong thanks to high-quality Inox tube frame construction. Powder rheology is the study of the behaviour of powders as bulk assemblies, consisting of solids, liquids and gases. 2. In mass flow, there is no chance of ratholing, so the size of the bin is not important. was used to control the flow of powder. Keep in mind that the mass-flow bin design process is iterative. 8 lb/min Feed Density Index (FDI) 24. Full size image. 1.