(710, 500, 355, 250, 180, 125, 90 and 63 μm, sieves Retsch) using a sieve shaker (Retsch AS 200 digit, Germany) with a vibratory amplitude of 2 mm [40]. Explains how bulk solids flow influences the design of a plant or an installation. . • Stable and strong thanks to high-quality Inox tube frame construction. 1. The flow of powder in a hopper is linked to 3 properties : The powder internal friction : how easy the powder particle can move from each other. Materials interlock or bond together to form an arch above the outlet, blocking any flow. The critical dimensions of ESP hoppers, such as the outlet opening and hopper half angle must be confirmed to. Wall friction angle (against SS plate) = ϕ’ = 25º Bulk density = γ = 22 lb/cu ft Angle of internal friction. This was attributed to the fact that the poor flowability of APAP could cause ratholing and high flow variations, especially when the powder. Valves & Actuators. Air pads may be needed to move the first material and merely gravity or small vibrations can be sufficient for the second. 24hr Emergency Service. Also in the case of funnel flow, asymmetry is of no help when ratholing has to be avoided. Powder flow is a critical attribute of pharmaceutical blends to ensure tablet weight uniformity and production of tablets with consistent and reproducible properties. It offers automatic and controlled discharge of virtually any powder type, winning where other systems have failed. 2 Calculation of the Minimum Required Outlet. These problems lead to losses worth thousands of dollars at. It is critical to understand the type of hang-up that you may be experiencing. This might include vibration, free flow, or free fall. This method may be used for all powders, dairy and non-dairy products. The best way to establish flowability is to compare flow on a Flodex powder flow tester with the tablet configuration to determine whether the powder’s intrinsic flow is close or equivalent to the cross-section of the die. The key to feeding cohesive materials in a screw feeder is with the use of Flow Aids. The Circle Feeder can be used as a material feeder, large industrial feeder, laboratory feeder, powder. , 2018). 2. Arching = bridging: an arch-shaped obstruction forms above discharge outlet and prevents flow i. Senior Consultant responsible for developing Engineering. Keywords: live bottom, cohesive, powder, hopper design. 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. UNIT- 3: HANDLING OF SOLIDS (2 HOURS) Sliding and flow of powder, Method for free flowing powder and granules, methods for cohesive powders Bins, Vacuum and conveyor. pharmacopeial methods to characterise powder flow. Solution: Reduce Movement. Conducting studies throughout R&D and scale-up can help identify and isolate where in the process a formulation issue began. The mass flow hopper section ensures a uniform, controlled. Powder rheology is used in a wide range of industries to. Even high viscous material can be fed through the. Segregation Ratholing (Fig. Define Ratholing. . Hoppers. 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. 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. As a general rule, extremely fine powders (<200 mesh) deaerate and pack readily (dusts, talc, etc. 2. TheFlowability is the ability of a powder to flow, and it is measured as the time in seconds necessary for a given volume of powder to leave a rotary drum through a slit of a certain size. Powder rheology is used in a wide range of. . g. 456 inches. If the coarser particles stick to the sides of the hopper they can get rancid and contaminate the next batch. 2. Pacific, Joe Marinelli, president, Solids Handling Technologies Inc. flow, including ratholing, erratic flow, flood-ing and segregation. Apparatus. Ratholing. 11. This can lead to problems like buildup on the interior of tubes or vessels, or “ratholing” or “bridging” of product in hoppers. When working with bulk solids, especially in high-moisture environments, the material flow characteristics can change. Fine particles and low-density particles tend to float on the liquid surface, making powder addition extremely difficult (7). Flow difficulties at the blending step often manifest as slow/no discharge or ratholing. Ratholing occurs when discharge takes place only in a flow channel located above the outlet. Sometimes, slow mixing paddles can keep bridging and ratholes under control. 3. AirSweep breaks up material blocks and sweeps the vessel walls clean. reviewing these solutions, however, it’s important to understand. 1 Bulk solid handling Measuring the flow properties of bulk solids and how to use this information for the design of storage vessel. Mass flow develops when all the material in a silo is in motion whenever any is withdrawn. UK-based powder flow solutions firm Freeman Technology offers this video on how particulate materials react when aerated, loosely packed or. Ratholing. their manufacture are in powder form. True. 1. Modeling of particle mixing and segregation in the transverse plane of a rotary kiln. was used to control the flow of powder. 5). Ratholing, another flow arresting situation, is when material directly above the outlet flows but the rest of the powder mass closest to the walls does not, creating a tunnel. In some cases through the design procedure it is found that a. 1. Apparatus. This method may be used for all powders, dairy and non-dairy products. Circle Feeder is the premier choice feeder that can prevent the segregation during mass flow discharging. Silo Blending / Segregation 3. With. The flow properties that govern whether a powder is prone to ratholing include cohesive strength, wall fric-tion, and bulk density [1-5]. Silos and hoppers are particularly prone to this issue if the. 10a or M-cell that is. Forty 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. 10a or M-cell that is. m. 2 Mass flow bins sufficient cohesive strength that its critical rathole diameter (the flow channel diameter at Flooding and ratholing problems can be which a rathole becomes. Definitions: Bin: Any upright container for storing bulk solids. Valves & Actuators. A bridge forms when wall friction holds up the ends of the arch. 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. Powder Hand Process 4:293–299. A powder flow analysis is an indicator of how well formulation will release from the hopper during the tableting. Process Systems 1. Understanding the rheological properties of the. It is therefore imperative to know your powder properties in order to design the desired silo. Jenike shear testing has determined the following. 3b) occurs in case of funnel flow if only the bulk solid above the outlet is flowing out, and the remaining bulk solid - the stagnant zones – is consolidated and forms the rathole. Discharging aids. 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. The total powder flow can be controlled in the level 1 closed-loop operation as indicated in Fig. 2. The principles discussed in this chapter can be applied to analyzing new or existing equipment designs. e. Keep product moving by preventing buildup, bridging and ratholing. However, flow aids are sometimes used when they are unnecessary and. 11. The hopper must be designed so the outlet diameter is larger than the outlet rathole critical diameter. 1016/0009-2509 (96)00250-3. ) (Ganesh et al. The gyrators also reduce particle segregation to make sure each bag is completely. Hoppers designed for mass flow with high quality surface finishes can address these issues. Still, the material at the bin walls remains stagnant and leaves. Material hang-up (arching and/or ratholing) problems are generally caused by one of four things: cohesive forces between powder particles or granules, external forces, inter-particle locking, or elastic constraint issues. This chapter provides guidance in designing bulk solid (“powder”) handling equipment to provide consistent, reliable flow and to minimize segregation. The large open inlet exceeds most materials’ critical arching diameter, preventing bridging and ratholing. g. In this work, the piping flow of cohesive granular materials in a flat-bottomed silo is investigated using finite element method (FEM). Material builds up on the vessel walls, restricting the flow and the vessel’s full storage capacity. The key to feeding cohesive materials in a screw feeder is with the use of Flow Aids. Air displacement as the product flows from the container can cause segregation, leading to an inconsistent end product. m. piping or ratholing may occur. Many of these flow issues can be traced back to improper discharger or feeder designs. Flow rate evaluationThe model elucidated the impact of the material descriptors for density; powder flow; particle size; compressibility; permeability and wall friction angle on the feeding process. 3485 Empresa Drive San Luis Obispo, CA 93401 Tel: 805-541-0901. This creates a non-flow regime whereby a discharge aid is needed to re-initiate powder flow from the silo. A better approach to predicting flow behavior is to take the characteristics of wall friction (φ w ). "Rotoflo is the best silo discharger! Mass flow develops when all the material in a silo is in motion whenever any is withdrawn. the powder flows at the place of the smallest flow resistance. Ratholing; c. Researchers at Purdue University have developed a new technology that solves the caking, bridging, and ratholing that occurs in powder flow from hoppers and bins in agriculture. 4. Conversely, StarTab hadPoor material flow doesn’t just affect productivity. 6 Therefore, a material that has poor powder flow needs to be pre-processed before attempting direct. 26. They all refer. A proven and practical scientific approach for designing bins and feeders based on a material’s flow properties. These issues are most likely due to improper storage, a poorly selected. Bulk Material. Effective feeder design not only enhances the flow within bins, hoppers, and stockpiles but also. The hopper design plays a role in this as hoppers with sharp angles and rough surfaces can inhibit powder flow. flow rate through an orifice compressibility index and hausner ratio angle of repose shear cell. powder flow problems. 2. Besides that, powder flow can be determine by the angle of repose make by the powder itself when poured onto a flat surface throughout the hopper. If your effective is 20’ after 3 days at rest the rathole dimension is 18. A high fat powder (HFP) with 73% milk fat content, whey permeate powder (WPP) with 86% lactose, rennet casein powder (RCP) and sodium caseinate powder (SCP) were donated by Kerry Ltd. Cocoa powder storage in silos, hoppers and bins can be fraught with blockage problems such as bridging and 'ratholing' because of its cohesive. forms. Discharging aids. Expanded flow silos and stockpiles are recommended for storing large quantities of non-degrading materials and for modifying existing funnel-flow silos to correct problems caused by arching, ratholing and flushing. The aeration of the disk fluidizer utilizes directional air flow along the wall of the chamber to loosen product and move it to the discharge point. The. Predicting powder flow behavior is important to successful solids-handling processes. 5 kg) of gas at a pressure of less than 15 psig (~1 barg). For calculation of bridges and ratholing in silos, there are two main phenomena to be. 1 Importance of powder flow in the pharmaceutical industry 6 1. Retrofit solutions. Motor with gear suitable for running at 30 rpm. Figure 3: Stagnant, cohesive powders can form a stable rathole in funnel flow. As the level of fly ash in the flow channel drops, a resistance to further flow into this channel occurs due to. 8 feet 12. . Silo blockage. Meet hygiene and safety requirements and remove the risk of cross-contamination. mechanical interlocking of large particles forming an arch 2. Flow and potential rathole formation in conical hoppers. Rotoflo is designed to help with material handling ensuring that silo discharge is free-flowing and controlled when handling a number of diverse materials. Powder strength data at each consolidating stress are plotted on the graph in Figure 4 to produce a graph called a “flow function. The orifice flow behaviours had thus corroborated with the powders' flow properties. , useable) capacity, as low as only 10–20% of the bin’s rated storage capacity. • Minimal power consumption. Hoppers designed for mass flow with high-quality surface finishes can address these issues. The two most common flow problems experienced in a silo, bin or hopper are arching (bridging) and ratholing. 3 pg 267. 10. Why are my powders are not flowing efficiently? In ratholing, a vertical flow channel develops above the hopper outlet and, once emptied, remains stable. In advance of her appearance at this year’s Powder Show Toronto running from June 4-6 at the Toronto Congress Center in Canada, Tracy Holmes, the president of Jenike & Johanson, Ltd. To achieve this, a flow agent should adhere to the surface of particles of solids as shown in Figure 2. m. the powder blend exhibit ‘Funnel Flow’. 1. If the material being handled is cohesive, the material outside of this channel will not flow into it and may cake or agglomerate. Matcon designs and manufactures powder handling equipment that can be used to improve manufacturing processes across a range of applications. The primary design objective when determining the bin geometry is to ensure that bulk solid or powder will flow with the effects of gravity, and without flow obstructions occurring. The bulk material continuously in motion. Bioprocess Equipment for biotech and pharmaceutical industries. All figures are courtesy of the authors. To avoid problems in silos concerning flow, product ageing or decay, silo design is necessary. Whether powder will flow smoothly or in an erratic manner inside a bin or a hopper depends on the flow pattern inside that equipment. Arching, ratholing, caking, segregation and flooding are some of the commonly encountered flow problems in the handling of fine powders. 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. Data were presented as mean. Flow and potential rathole formation in conical hoppers. Due to the pressure, some solids tend to be more cohesive , when powders become cohesive, they can form archs or rathole , 2 phenomena very detrimental to the flow of powder and. powder addition easier. The powder flow function is a plot of unconfined yield strength versus major principal. , “Increase Powder. The simplest way of explaining the flow function is with the uniaxial unconfined failure test shown in Figure 4, which measures the. b. They all have one thing in common: none will predict whether or not a powder will flow in a hopper. powder becomes deaerated in the stagnant region of a funnel flow bin, it usually develops 2. Larger particles are more likely to penetrate the surface than fine particles. Material builds up on the vessel walls, restricting the flow and the vessel’s full storage capacity. 4. In arching, the material forms an arch (or a bridge) above the outlet that prevents further flow. 1 Shear strength. High cohesive strength may result in the formation of a stable rathole. to 11 a. 24hr Emergency Service. In this case, powder discharge from hopper is not predictable. Mass Flow also allows the most efficient outlet. Process Control & Automation. The ladder bowl allows the powder to flow evenly around this insertion station and keep a better powder level at the first tamping station. Material flow from a bin or silo is inextricably linked to how the feeder extracts the material from the bin outlet. The powder has relatively low cohesive strength. Powder flow is critical to a range of pharmaceutical manufacturing processes. Robert Sedlock. Keep in mind that the mass-flow bin design process is iterative. Arching or bridging is a flow-arresting situation whereby the powder mass creates a structure (such as a dome or a bridge) above the outlet hole inhibiting flow completely. 1991; Holdich. The design of a silo is based on the most economical case: gravity flow. 4. Discharge of powder from a hopper or bin is a common operation in solid dosage form manufacture. Unstick material and promote even flow. These behaviours are related to the cohesive strength of the powder, which is a function of the applied consolidation pressure. offers powder testing services (flowability, friction, time consolidation, strength as used for comparative tests, silo design for flow and silo design for strength) and. The flow properties of a bulk solid can have a significant impact on process efficiency and the success of the end product. Posted by Control Concepts USA on September 13, 2022 7:13 pm. flowability to avoid problems during blending, compression, filling and transportation (Räsänen 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 powder influences the silo by the flowability of powder causing bridging and ratholing. An arching flow p Figure 3. Materials interlock or bond together to form an arch above the outlet, blocking any flow. powder becomes deaerated in the stagnant region of a funnel flow bin, it usually develops 2. Eliminate bridging, rat holes, and stuck material. was used to control the flow of powder. Flow problems, such as ratholing, arching, and erratic flow, can be eliminated with appropriate container geometry. 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]. Jenike, who pioneered the theory of bulk solids flow at the University of Utah in Salt. The material that is. The large open inlet exceeds most materials’ critical arching diameter, preventing bridging and ratholing. 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. Motors & Drives Valves & Actuators Powder & Bulk Solids. Hoppers designed for mass flow with high-quality surface finishes can address these issues. See Fig. Effective feeder design not only enhances the flow within bins, hoppers, and stockpiles but also positively. k. Boateng AA, Barr PV. 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. 4. Ratholing is influenced by the bin/hopper geometry and outlet size the material is fed through. For powders such as T100 and T100M which exhibit arching and. 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. Antimicrobial AlphaSan RC 5000 / RC 2000 Powder Flow Characteristics Flow Rate Indices Flow Rate Index (FRI) 115. Powder & Bulk Processing. 2002). pharmaceutical tablets, detergents, ceramics, powder metallurgy etc. 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. Erratic flow results when ratholes collapse, causing the powder to arch as it impacts the out-let. 14. One of the recommended types of flow aids is called Mechanical Agitation. Eliminate bridging, rat holes, stuck material and uneven flow in chutes and pipes. the types of flow problems that can occur and the flow patterns. Basic silo shapes: a conical; b wedge-shaped; c asymmetric wedge-shaped; d. This device mixes with the bulk powder to increase. Oil-lubricated, oil-cooled gyrators induce flow and eliminate bridging and ratholing. Knowledge about bulk density of materials is essential for avoiding ratholing and arching effects in silos and hoppers. Case Studies Keep product moving by preventing buildup, bridging and ratholing. The depth of the trough into which the powder is filled is 12 mm and. Of course the outlet of the hopper has to be large enough to prevent bridging above the feeder. From the test results, you can follow Andrew Jenike's analyses to predict flow behavior in hoppers, e. a cohesive arch when particles bond together ii. The nozzle releases highly pressurized air pulses to promote on-demand, first in and first out flow. The outlet is the smallest flow channel through which the bulk material should move. encountered issues with achieving a consistent feed rate of a highly drug-loaded pre-blend due to the poor flowability and packing consistency. The rest of powder compacts under vibration and get les flow-able in the time, so if a flow channel is established it will stay on the same place. Hoppers designed for mass flow with high-quality surface finishes can address these issues. Because of this flow pattern, funnel flow silos that are not emptied. Powder Machine Parameter Value/Equation 1 Jenike 1 Inst Flow Function 0. (For an illustration of arching and ratholing, see the online version of this article at If a stable rathole forms in a hopper,They also prevent ratholing of hoppers and prevent lump formation. Arching/Bridging & Ratholing. /d. Topics covered in this lecture include flow problems due to arching and ratholing, flooding issues, limiting discharge rates and segregation problems. For decades, Industrial Vibrators and Air Blasters have helped restore flow to bulk solid materials. At the heart of our valves is Matcon's world-famous Cone Valve Technology delivering efficient and flexible powder handling solutions, serving a range of. Occurs for small outlet size =< 6-10 * max particle size (D 90 ) b. Solimar Fluidisers create twice as much aeration action as many lookalikes. Reduce costs in manual labor for unsticking materials from bins or hopper walls. Air Cannons For Solving Tough Material Flow Problems. Typically, they are used when flow by gravity alone will not work or when it is impractical to provide the design that is required for reliable flow. This is often not taken into account and can result in arching or ratholing in storage bins or silos, blockage of chutes, flooding of hoppers and other problems that may affect the performance of the plant. The obstruction to flow would have a significant impact on the overall CM process as it. 5). A mass flow screw feeder prevents preferential flow which can lead to ratholing and arching problems. Critical Rathole Diameters, Df, ft—“D” is the diameter of the opening required to collapse a rathole, while “f” stands for funnel flow. In all applications, this fluidizer prevents bridging, ratholing, and material hang-ups. Many of these flow issues can be traced back to improper discharger or feeder designs. powder flow problems. c 3 Critical condition for flow. 57. If the powder does not bind sufficiently to another material, it will separate through fluidization if aerated or allowed to free-fall. pub/extras. 1 Importance of powder flow in the pharmaceutical industry 6 1. It is critical to understand the type of hang-up that you may be experiencing. An arching flow p Figure 3. Our pneumatic and electric bin and hopper vibrators will: Promote the consistent and controlled material flow of dry or semi-dry bulk materials. Irregular flow; d. g. Shear cell techniques were used to measur e the following powder flow pro-perties: powder flowfuncti on, effective angle of internal fricti on and angle of wall friction. Exceptions are the ore concentrate or fine powder bins which usually are of the mass flow type. Joe will describe uses for liners such as TIVAR 88 and 2B stainless steel along with coatings such as electrostatic powder coatings and Plasite 7122 epoxy coating. 1. Arching. Caking of powder can have adverse effects on solubility, mixing, and dispersion resulting in loss of products, delays in launch and consumer complaints. Measuring flow properties leads to proper equipment selection and process reliability. Powder flow can be defined as the ease with which a powder will flow under a specified set of conditions. 2. As the level of material in the flow channel drops, a resistance to further flow into. size, form, elasticity, water content and temperature, which influence compressibility. 2002). The flow channel drains material in the middle first. , flow pattern (mass flow or funnel flow), and obstructions to flow (arching, ratholing). View our Flow Solutions Video! One of the most common problems with bulk material flow is a condition known as ratholing. The corresponding control schemes at different levels for the feeding-blending system are provided in Table 6. Jenike & Johanson is a world leading technology company for powder & bulk solids handling, processing and storage. offers powder testing services (flowability, friction, time consolidation, strength as used for comparative tests, silo design for flow and silo design for strength) and solves practical problems in the field of bulk solids handling (silo design for flow to avoid problems like arching, segregation, ratholing) on the basis of the mechanical properties. Keep in mind that the mass-flow bin design process is iterative. 400 Business Park DriveRatholing is a scenario that powder starts. Only with a not too poorly flowing bulk solid might it be possible that flow obstructions occur somewhat less often in asymmetric funnel flow silos compared to symmetric ones, because lessDetermine wall slopes for mass flow, by measuring the friction that develops between a bulk solid and any hopper wall material. Typically, a dilute phase line conveys less than 15 lb (~7 kg) of solids per pound (~0. Flow obstructions occur when the forces opposing motion exceed the forces promoting. the relationship is called powder flow function Yield locus and family of yield loci Determination of y and c. This can disrupt your production line. No ratholing! The slow rotating vanes move the material radially from the center to the outlet ensuring "first in -first out" mass flow; Slow rotating parts insure gentle product handling and minimum downtime; Turndown ratio up to 10:1; Low maintenanceHopper and Silo Ancillaries. The hopper to be designed is conical. 2. If you are experiencing issues with dust in your manufacturing facility, it is probably due to open processing. Predicting the flow characteristics of powders during manufacture is especially important for the pharmaceutical engineer. 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. 3. A bin experiencing ratholing will have limited live (i. 24hr Emergency Service. Able to work with a variety of material with flow adjusting mechanism. Home; Blog; Case Studies; 770-255-1322. Discharge of powder from a hopper or bin is a common operation in solid dosage form manufacture. 4. Air displacement as the product flows from the container can cause segregation, leading to an inconsistent end product. Jenike & Johanson is presenting the following AIChE sponsored courses June 18-20 at the Canadian Management Centre in Toronto:Flow of Solids in Bins, Powder Bulk Solids is part of the Informa Markets Division of Informa PLCRat-holing problem: * is one of common powder flow problems * When powders are released via a butterfly or slide valve, flow takes place directly above the container outlet. The hopper design can play a role in this as those with sharp angles and rough surfaces can inhibit powder flow. 26. To mitigate process variations and disturbances caused by such risk scenarios, closed-loop feedback control is required. 20-36 , wherein there is shown a hopper assembly H which utilizes a hopper 401 and a hermetically sealed cover 402. 5D Bunker: A shallow bin, where H < 1. 2. Table 1 – Flow Property Parameters Measured on Three Powders with the Jenike and Peschl Testers . 8 lb/min Feed Density Index (FDI) 24. The flow behaviour of the. FLOW PROBLEMS 2. Discharge of powder from a hopper or bin is a common operation in solid dosage form manufacture. 3. Reduce costs in manual labor for unsticking materials from bins or hopper walls. User Tools. bulk solid materials exhibit in bins and silos. Ratholing is a flow obstruction that can cause erratic discharge from a bin, as well as induce material caking. Figure 10. Check drain valve on drier is open: check oil and water separator : Poor fluidisation of the powderRatholing Ratholing is a condition in which the stored material does not slough into the central flow stream for discharge and instead forms a core. The technology is a microcontroller actuated portable device that can be remotely controlled. 4. LIW feeder flow rates can be compromised when the sudden change of the powder weight (e. 59 2 Effective Angle Intl Friction 53. Particle size distribution (PSD) estimation by sieving of the two powders was performed according to Ph. The way bulk powders flow impacts on the design of. 2 pg 266. Dense phase. Why Battery Manufacturers Choose the Circle Feeder. Bulk solids problems such as bridging, ratholing and demixing are proactively prevented. Based upon mathematical models, Jenike developed design charts to determine which flow pattern is to be expected during gravity discharge from a bin or hopper. The reason for this is that when a result in a flooding condition at the outlet. Full size image. A Brookfield Powder Flow Tester, equipped with Powder Flow Pro software for automated instrument control and data acquisition, was used to test this name brand baby formula. While addition of magnesium stearate had improved powder flow, ratholing was still observed for T100M across all orifice diameters.