, answered a few questions from Powder & Bulk Solidson common powder handling and flow issues and how operators can take steps to fix or prevent. Polimak Bin Activators are used in several industrial applications to efficiently discharge dry solid materials in powder or granular form from upstream equipment, thereby, reducing bulk material bridging or ratholing while promoting mass. The Wolfenbuttel, Germany) is used for measuring the flow properties of bulk solids or powder ( fig. g. . the powder blend exhibit ‘Funnel Flow’. If a mass-flow bin is required based on the flow char-acteristics of the powder or bulk solids, the next step is to determine an appropriate outlet size and feeder. 3. powder becomes deaerated in the stagnant region of a funnel flow bin, it usually develops 2. Why are my powders are not flowing efficiently?Ratholing occurs when discharge takes place only in a flow channel located above the outlet. 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. 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. However, in powder pressing industries (e. 71 Funnel / core flow. The Cone Valve technology within each of the Matcon IBCs overcomes powder bridging due to both the lifting action of the cone and its integral vibration during lift. The limiting condition for flow: c y ff - to reveal conditions under which the flow will occur. The reason for this is that when a result in a flooding condition at the outlet. At this point, peripheral bulk materials remain in place, so the hopper cannot be emptied. For calculation of bridges and ratholing in silos, there are two main phenomena to be taken in consideration. Poor flowability of powders in a hopper means that flow obstruction due to arching occurs or uneven flow causes ratholing. Powder blockage in silos. m. Discharging aids. Ratholing; c. The reason for this is the strength (unconfined yield strength) of the bulk solid. While bulk solid and powder handling is extremely common in industry, even some of the most basic fundamentals of material handling remain poorly-understood – largely because our education generally only. 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. . The corresponding control schemes at different levels for the feeding-blending system are provided in Table 6. the powder flows at the place of the smallest flow resistance. Breakthrough Products Awards. Ratholing is influenced by the bin/hopper geometry and outlet size the material is fed through. What Can Cause A. Powder Hand Process 4:293–299. 0”. Consequently, meas-urement of the wall friction characteristic of a. Prevent bridging and ratholing. 10). If you have material flow problems like arching, bridging, ratholing or material sticking to the sides of your bin, then a VIBCO Air Cannon can help! The VIBCO Air. 5). ) the powders are filled into closed cavities; this is followed by compaction using rigid punches and finally the product is ejected from the die. g. 1 is handled? Is the 100-mm diameter outlet of the hopper large enough to prevent an obstruction to flow?Powder flow tester, Software for silo design. Powder Rheology. 448 m, respectively), corroborating the previous results that demonstrated that shape had more. The entire process is user-controlled and transparent: Diagrams and extrapolations. 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. Powder rheology is used in a wide range of industries to. 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. Basic silo shapes: a conical; b wedge-shaped; c asymmetric wedge-shaped; d. discharge) and its flow rate have been used to measure (USP 1-May-2024) powder flow. The flow of powder out of a silo is stopping primarily for 2 reasons ; either formation of arches. How to prevent ratholingAuthors: Dietmar Schulze. Process Control & Automation. Solids behave differently than liquids, he said, but flow problems are preventable with the proper design and tactics. , 2018). 487 and 1. There are many factors, e. Before. g = gravity constant. Many factors can lead to ratholing in your hopper, bin, or silo. m. Erratic flow results when ratholes collapse, causing the powder to arch as it impacts the out-let. 2 pcf Bin Density Index (BDI) 40. More than 70% of all products contain ingredients that are handled in bulk solid form at some point during the production process. The 2-in. Flow aids are used to return to a more regulated flow pattern and are relatively inexpensive. It is the only flow aid that can handle. Whether powder will flow smoothly or in an erratic manner inside a bin or a hopper depends on the flow pattern inside that equipment. This was attributed to the fact that the poor flowability of APAP could cause ratholing and high flow variations, especially when the powder. 3. The material forms a narrow passageway above the feed auger or outlet, while the remaining materials in the storage structure are stationary and can begin caking to. Powder strength is measured as “yield stress” by shearing particles trapped in the lid pockets against particles in the shear cell. 3485 Empresa Drive San Luis Obispo, CA 93401 Tel: 805-541-0901. 1. Antimicrobial AlphaSan RC 5000 / RC 2000 Powder Flow Characteristics Flow Rate Indices Flow Rate Index (FRI) 115. Dust management, flow promotion, level monitoring and a wide variety of. Ratholing is a common flow issue in storage structures. 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. Flowability 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. 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. The reason for this is that when a result in a flooding condition at the outlet. 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. . In a bin, the powder is submitted to pressure, due to the fact that there is a height of powder in the bin, the powder on top pushing on the powder below the hopper. Comparison of the flow properties of eight commercial dairy powders5. Hoppers. Conducting studies throughout R&D and scale-up can help identify and isolate where in the process a formulation issue began. 8 lb/min Feed Density Index (FDI) 24. The two most common flow problems experienced in a silo, bin or hopper are arching (bridging) and ratholing. Flow splitting increases capacity and saves floor space. Ratholing. 4. To improve the flowability of powders, flow aids or lubricants such as magnesium stearate are often incorporated in formulations. flow, including ratholing, erratic flow, flood-ing and segregation. 5). Example: Calculation of a Hopper Geometry for Mass Flow An organic solid powder has a bulk density of 22 lb/cu ft. Many of these flow issues can be traced back to improper discharger or feeder designs. Hoppers designed for mass flow with high-quality surface finishes can address these issues. 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. was used to control the flow of powder. Eur. capacity — as low as only 10–20% of the bin’s rated stor- age capacity. 24hr Emergency Service. 1 Test Methods. Ratholing. Consequently, meas-urement of the wall friction characteristic of a. 1 Shear strength. pharmacopeial methods to characterise powder flow. Critical Rathole Diameters, Df, ft—“D” is the diameter of the opening required to collapse a rathole, while “f” stands for funnel flow. 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. The reason for this is that when a powder becomes deaerated in the stagnant region of a funnel flow bin, it usually developsFlow 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. ratholing, flooding, and inadequate flow rates, and more. Powder flow is a critical attribute of pharmaceutical blends to ensure tablet weight uniformity and production of tablets with consistent and reproducible properties. It is therefore imperative to know your powder properties in order to design the desired silo. rathole, bridging and segregation to occur. When working with bulk solids, especially in high-moisture environments, the material flow characteristics can change. In practice, this group of bulk materials is the most common. , wedge-shaped and transi-usable capacity of the vessel. Impact on filling. Thus, reliable information of flow properties of the pulverized coal concerned is required for reliable flow from the hopper, which is essentially crucial in handling and processing operations [8], [9]. flow, including ratholing, erratic flow, flood-ing and segregation. 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. size, form, elasticity, water content and temperature, which influence compressibility. 1. steeper than. Ratholing = funnel flow: discharge. Bridges of powder can form in your containers preventing flow. LEARN MORE Powder Cone Valve System. Google Scholar Wilms H (1992) Inserts in silos for blending. True. Eliminate bridging, rat holes, and stuck material. 26. What Can Cause A. Mixing & Blending. If the powder does not bind sufficiently to another material, it will separate through fluidization if aerated or allowed to free-fall. Motor with gear suitable for running at 30 rpm. Bridging, ratholing, arching and comparable behaviors are the bane of powder handling and formulating. Bridging is the inverse of ratholing—instead of a void, a bridge of material forms and refuses to flow or move. flow rate through an orifice compressibility index and hausner ratio angle of repose shear cell. 1 Importance of powder flow in the pharmaceutical industry 6 1. e. Topics covered in this lecture include flow problems due to arching and ratholing, flooding issues, limiting discharge rates and segregation problems. Visually detectable local ratholing and cratering in the fluid bed: Compressed air too moist, contains oil; relative humidity is too high inside the room in which the powder is processed. The powder's flow pattern has a major effect on the development of certain flow problems, especially flooding. Jenike, who pioneered the theory of bulk solids flow at the University of Utah in Salt. • Separate paddle propulsion possible. Arching occurs when large particles interlock to form an arch at a hopper outlet and stop flowing due to shape, pressure, moisture or temperature. 1 Funnel flow bins When a fine powder is stored in and discharged from a bin having a funnel flow pattern, ratholing and flooding problems are almost inevitable. 3 and Fig. readiness of a powder to flow -. 10. These problems lead to losses worth thousands of dollars at. 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. 3’ diameter opening is required to collapse a rathole, even at this low head. Ratholing is influenced by the bin/hopper geometry and outlet size the material is fed through. Our comprehensive line of feeding technology can provide: high and low feed rates, batch, continuous, high. Solimar Fluidisers create twice as much aeration action as many lookalikes. However, determining the physical properties under normal operating conditions is essential. 26. In this case, powder discharge from hopper is not predictable. Flow occurs in most powder-based processes, opposed by various cohesive forces. It offers automatic and controlled discharge of virtually any powder type, winning where other systems. spoilage, flooding, or ratholing are likely to occur, then a mass-flow discharge pattern should be selected. Calculation of a Hopper Geometry for Mass Flow An organic solid powder has a bulk density of 22 lb/cu ft. The hopper design can play a role in this as those with sharp angles and rough surfaces can inhibit powder flow. Efficiency– As explained earlier ratholing powder flow can be likened to creating a “funnel effect”,meaning silos and hoppers cannot be used to their full storage capacity. If the material being handled is cohesive,. outlet dimensions to avoid arching and ratholing. Air Cannons For Solving Tough Material Flow Problems. Consolidations can therefore be undone. If you are experiencing issues with dust in your manufacturing facility, it is probably due to open processing. The bulk material continuously in motion. the types of flow problems that can occur and the flow patterns. Andrew W. The simplest way of explaining the flow function is with the uniaxial unconfined failure test shown in Figure 4, which measures the. Arching, ratholing, caking, segregation and flooding are some of the commonly encountered flow problems in the handling of fine powders. The flow behaviour of the. Depending on their makeup, products in powder or bulk form are prone to cling to surfaces, especially if they’re high in fat or moisture. 327. Despite being a simple test of compressibility, it can be useful for identification of powder flow behavior. • Stable and strong thanks to high-quality Inox tube frame construction. 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. Finally. poor flow properties, which leads to ratholing. 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. Movement speeds up material segregation. powder becomes deaerated in the stagnant region of a funnel flow bin, it usually develops 2. 1991; Holdich. , et al. Particle size also affects wetting. Lower the total height requirement. Are they steep enough to prevent ratholing when a powder having an FFC of 7. 363 14. Robert Sedlock. 125”; vibrator with 1-¼” piston. For powders such as T100 and T100M which exhibit arching and. 3. Rotoflo is designed to help with material handling ensuring that silo discharge is free-flowing and controlled when handling a number of diverse materials. 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. Material Flow Solutions, Inc. The reason for this is that when a result in a flooding condition at the outlet. Cleveland Vibrator Company offers a range of solutions for manufacturing and processing powder products from bin vibrators, feeders and conveyors to screeners for 10 micron and up. A critical orifice measurement apparatus was developed to study powder flow initiation from an arching state into an enclosure where the air pressure is reduced. Discharge of powder from a hopper or bin is a common operation in solid dosage form manufacture. 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. Discharge of powder from a hopper or bin is a common operation in solid dosage form manufacture. 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. 10). Figure 2: The two primary flow patterns that occur in gravity discharge are funnel flow and mass flow. their manufacture are in powder form. Process Control & Automation. Equipment for powdered metals, ceramic powders, pigments, chemicals, super-abrasives. Unstick material and promote even flow. Scope. . 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. A key variable that will have an impact on the flow is its cohesive strength. The flow properties of a bulk solid can have a significant impact on process efficiency and the success of the end product. Process Control & Automation. Process Systems 1. Table 1 – Flow Property Parameters Measured on Three Powders with the Jenike and Peschl Testers . aid, modifying the feeder, or using gas injection. The orifice flow behaviours had thus corroborated with the powders' flow properties. 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. Cohesive Strength – The consolidation of powder may result in arching and ratholing within transfer equipment. hopper that gives mass flow with one powder may give core flow with another. 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. Eastern/11 a. Driveshaft Removal:is a scenario that powder starts. Also in the case of funnel flow, asymmetry is of no help when ratholing has to be avoided. 3. The aim is to provide a dynamic picture of the piping formation, so as to explore the variation of field. There are two main reasons why no-flow conditions happen: arching and ratholing. 1. 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. A proven and practical scientific approach for designing bins and feeders based on a material’s flow properties. Wall friction angle (against SS plate) = ϕ’ = 25º Bulk density = γ = 22 lb/cu ft Angle of internal friction. Traditional powder testing methods cannot force the bridging to occur in a repeatable manner and thus they cannot discriminate flow differences between powders. 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. 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. In a silo, hopper or bin, the powder is exposed to various pressure. 1. Discharge of powder from a hopper or bin is a common operation in solid dosage form manufacture. Unload and produce good faster in your production process. adhesive nature of a material could influence the feedability of materials over time through screw layering or bridging/ratholing, limiting the powder flow through. reviewing these solutions, however, it’s important to understand. Mechanical Agitation when used properly will condition the material to a uniform bulk. Mixing & Blending. Typical powder flow issues found in the hopper are ratholing, bridging and segregation. Definitions: Bin: Any upright container for storing bulk solids. Ratholing. 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 is critical to a range of pharmaceutical manufacturing processes. Under the silo a screw feeder with a varying pitch. Bridging, ratholing, arching and comparable behaviors are the bane of powder handling and formulating. The reason for this is that when a powder becomes deaerated in the stagnant region of a funnel flow bin, it usually develops 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. 93+0. ), and dry, uniformly-sized larger materials will be free flowing. When your bottom line depends on moving product efficiently through your plant, obstructions. 2. As the level of fly ash in the flow channel drops, a resistance to further flow into this channel occurs due to. Flow agents are used to enhance the flow behavior of solids by reducing the inter-particle adhesion force. View our Flow Solutions Video! One of the most common problems with bulk material flow is a condition known as ratholing. Ratholing/ funneling 5 Inconsistent flow 3 Electrostatics Flowability Compaction . , 2003). 1. 2. FLOW PROBLEMS 2. Retrofit solutions. Powder rheology is the study of the behaviour of powders as bulk assemblies, consisting of solids, liquids and gases. n 1. 4 Feeders used at discharge of hopper. They all refer. Ratholing is a term used to describe extreme cases of funnel flow where the material nearer the walls is completely stationary and only the central material is discharged . 4. c. (Powder and Bulk Solids) (regular, part-time and distance learning) • PhD (Powder. On Wednesday, September 21, 2022 at 2 p. To ensure issues don’t persist or escalate, it’s important to fix the issue as. This can usually be overcome by. Ultrasonic excitation minimizes static friction forces and allows bulk solids to flow more continuously and efficiently. Flow aid devices are internal or external devices that are used to assist in discharging materials from a bin, hopper, or silo. Our in-house testing laboratory measures the flow properties of your material so our solutions are robust - your product will flow through your system without hang-up, arching, , ratholing, blocking or other flow issues. PHARMACEUTICAL ENGINEERING. Discharge of powder from a hopper or bin is a common operation in solid dosage form manufacture. "ratholing" can occur, that is, the diameter at which. In plug flow bins, the material flows in the centre of the bin, into which the sides slough as the material is drawn from the bin. 1991; Holdich. to 11 a. Arching. Powder strength data at each consolidating stress are plotted on the graph in Figure 4 to produce a graph called a “flow function. The lifting action of the cone breaks up bridged product and prevents material from rat. When the flow channel empties and material flow ceases, it can form a stable rathole that may collapse and block the opening. 5). Geometry modifications are. doi: 10. These are examples of material flow problems. Abstract. The energy requirements are very dependent on the bulk solids or powder flowability properties, including cohesion and internal shear angle. e. 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. In most cases, the vessel or bin can be attached to a vibrator, which shakes the vessel to pack the powder together. Flow function test. W. Bulk solids and powder flow properties testing is considered mandatory when designing screw conveyors and screw feeders for handling difficult to manage products. 770-255-1322. To mitigate process variations and disturbances caused by such risk scenarios, closed-loop feedback control is required. Use the following guidelines for impacting vibrators: Wall Thickness of 0. Eliminate bridging, rat holes, and stuck material. described ratholing and powder bridging in a small-scale feeder for fine, cohesive and compressible powders (Santos et al. (USP 1-May-2024) Of particular significance is the utility of monitoring flow continuously, since pulsating flow patterns have been observed even for free-flowing powders. 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. To find out more about Rotoflo, contact rotoflo@severfield. The gravy mix was scooped into the trough, and the. k. Mass flow exhibits a first-in-first-out flow sequence, allowing the product at the bottom (coarser or heavier particles) to discharge first. 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]. Avoid silo problems, such as bridging, funnel flow, ratholing, arching, segregation and product decay. 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. Rat holing is where a central void develops above the discharge outlet in place of the active flow channel. This can disrupt your production line. 11. Eliminate Bridging and Ratholing The Carman Vibrating Bin Discharger eliminates. This might include vibration, free flow, or free fall. Powder rheology is used in a wide range of. 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 way bulk powders flow impacts on the design of. As a general rule, extremely fine powders (<200 mesh) deaerate and pack readily (dusts, talc, etc. 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. 2002). Flow difficulties at the blending step often manifest as slow/no discharge or ratholing. • The particle size distribution – indicator of powder flow and the segregation potential • Bulk and tapped density – indicator of powder flow, mixing (fill volume) and tablet die filling. High cohesive strength may result in the formation of a stable rathole. If the material is even slightly cohesive, material may stick to the walls and eventually become part of the bin structure. The most common and serious problem is no-flow, due to arching or ratholing [6], [7]. a. Ratholing occurs when material in the center discharges completely while material nearer the walls of the hopper remains in place. , Listowel, Ireland. The vane lid is used to perform the flow function test. 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. Home; Blog; Case Studies; 770-255-1322. Discharge of powder from a hopper or bin is a common operation in solid dosage form manufacture. 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. In order to achieve mass flow, tion hoppers) are shown in Figures 5 and 6, respectively. 400 Business Park DriveRatholing is a scenario that powder starts. This was attributed to the fact that the poor flowability of APAP could cause ratholing and high flow variations, especially when the powder. Funnel-flow bins lead to ratholing when the non-flowing solid consolidates sufficiently to remain stable after the channel has emptied out, and to flushing of powders as the layers slough off the top of the non-flowing mass and hit the bottom of the channel, or as aerated material rushes through a rathole. Granular materials can exhibit complex solid- and liquid-like behaviours which are not fully understood. Pumps, Motors & Drives. For example, when conveying powders that tend to cake or pack, it will be necessary to feed the aeromechanical conveyor from an infeed hopper of steep-wall design that encourages material flow along the hopper walls and prevents bridging and ratholing of the material. Figure 10. The large open inlet exceeds most materials’ critical arching diameter, preventing bridging and ratholing. In addition, poor flowability can also cause content uniformity concern because of insufficient mixing. Ratholing of powders can occur in a container (silo, hopper, IBC, mixer vessel) when the powder empties through a central flow channel. While addition of magnesium stearate had improved powder flow, ratholing was still observed for T100M across all orifice diameters. com. Arching and Ratholing does not occur. 1. Powder & Bulk Processing. As the level of material in the flow channel drops, a resistance to further flow into. A bin experiencing ratholing will have limited live (i. In the present work, the discharge characteristics of non-gravity-driven powder in the horizontal silo were investigated experimentally, with an emphasis on the half cone angle, aeration. In silos and hoppers it’s often the cause of flow problems like ratholing and bridging. In all applications, this fluidizer prevents bridging, ratholing, and material hang-ups. Valves & Actuators. 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.