Polimak designs and manufactures three distinct rotary valve models, each tailored for specific applications:
• Flow-Through Rotary Valves
• Blow-Through Rotary Valves
• Off-Set Rotary Valves
Our rotary valve design variations provide customers with a broad selection of models for handling different dry bulk materials with varying properties. These valve models can be designed with different rotary valve drive connection configurations (LINK).
Flow-Through Model
Flow-through rotary valves are also referred to as drop-through valves, because in this model bulk material flows directly downward through the valve, moving vertically from the inlet to the outlet.
The inlet and outlet ports on the rotary valve housing are vertically aligned and have generally the same size.
During operation, empty rotor pockets are filled with bulk solids flowing vertically down from upstream equipment. These solids are then carried through the valve housing and vertically discharged through the outlet.
Drop-through valves are mainly used for non-cohesive, free-falling dry bulk materials such as sand, wheat, rice, coffee beans, and many others. For food and chemical industry applications, they can be made from stainless steel (AISI 304 and 316). Hardox steel is also an option for constructing these valves, providing enhanced durability when processing highly abrasive dry bulk materials.
Blow-Through Model
Blow-through model rotary valves are designed with troughs that connect directly to pneumatic conveying lines, allowing them to be installed within the conveying system without the need for additional intermediate equipment.
In this configuration, the rotary valve receives bulk solids through its inlet while the rotor rotates. A filled rotor pocket unloads the bulk materials into the trough, where conveying air moves the materials through the process line.
Blow-through rotary valves are primarily designed for handling sticky and cohesive bulk solids such as flour, milk powder, and custard. For food and chemical industry applications, blow-through rotary valve models are available in stainless steel (AISI 304 and 316). Hardox rotary valves are manufactured for handling abrasive bulk materials.
Off-Set Model
Off-set rotary valves, also known as slide-entry valves, have inlet and outlet ports that are positioned off-center from the valve housing’s vertical axis. This design allows for better alignment with equipment where the inlet and outlet ports are not vertically aligned, enhancing installation flexibility.
During the operation, as the rotor passes the valve’s inlet, the offset design causes the approaching empty rotor pocket to fill only partially. Partial filling minimizes bulk material shearing and prevents jamming of the rotor caused by dry bulk particles trapped between the rotor and valve housing. The volumetric fill efficiency of an empty pocket may vary depending on the bulk material, generally ranging from 40% to 60%.
Off-set rotary valves are commonly used to handle bulk materials like sunflower seeds, plastic pellets, and peanuts. For food and chemical industry applications, off-set rotary valve models can be produced using stainless steel (AISI 304 and 316). For abrasive dry bulk materials, the valves can also be made from Hardox steel.
Custom Design Rotary Valves
Polimak, relying on more than 40 years of experience and know-how, has significant expertise in the design and manufacturing of rotary airlock valves, ensuring solutions that meet our customers' specific application requirements across industries ranging from food processing to chemicals and plastics.
Our core competencies are technology integration and design synthesis. Meeting and exceeding our clients' expectations in operation, cost, and other factors requires integrating the appropriate levels of technology for each rotary valve application.
Polimak’s custom-engineered rotary valve production process includes problem definition, conceptualization, detailed design, material selection, prototyping, testing and validation, manufacturing, quality control, packaging, delivery, and installation. Our teams efficiently execute these steps and deliver custom-designed rotary valves within a rapid turnaround time.
These valves are typically actuated by pneumatic actuators and are used to automatically open and close the product flow to discharge material to downstream equipment.
Installed below silos or hoppers, these valves are used for maintenance operations of equipment such as rotary valves, screw feeders, etc., that are positioned below the butterfly valve.
These valves are typically actuated by pneumatic actuators and are used to automatically open and close the product flow to discharge material to downstream equipment.
In this design, the butterfly valve is sandwiched between two flanges. Rubber sealing at both faces of the valve provides a tight seal between the flanges and the wafer butterfly valve.
One side of the valve has a bolted flange connection, while the other side features a built-in short pipe designed for fixing a flexible sleeve.
These valves have bolted flange connections on both sides, making them suitable for installation on silos, hoppers, screw feeders, and similar applications.
Bulk tanker trucks or open trucks can be filled with powdered materials delivered within FIBC bags. These systems generally consist of bulk bag discharging station, mechanical or pneumatic conveyor and loading bellow. Big bag discharge station transfers the bulk solid from big bag to conveying system. Conveying system transfers it to truck loading area. And loading bellow is used to fill tanker truck without any dust emission. Since truck loading operations are done within limited time, high capacity big bag discharge systems and bulk material conveying systems are used. For short distances, screw conveyors are preferred to transfer material from big bag discharge station to truck loading chute. For long conveying distances, pneumatic conveying systems provide better service. There may exist a storage hopper or silo above bulk truck loading bellow to compensate material flow between inlet and outlet. Bulk bag discharge and truck filling systems have automatic control system that monitors product level in truck and operates all equipment accordingly. Optional weighing system can be added to measure the amount of material that is filled to truck.
Big bag discharge systems can deliver dry bulk solids in powder and granular form to weighing and batching systems. The loading hopper of the weighing system should remain full during dosing and batching. Big bag discharge systems can monitor the product level in the loading hopper and maintain a constant level automatically. Depending on the dosing speed and conveying distance, mechanical conveying systems or pneumatic loading systems may be used. Dust collectors can be employed to prevent dust emissions during hopper loading, especially for materials with high dust content.
Dry bulk packaging systems are used to fill powdered or granular materials into bags, drums, jars, sacks, etc. Bulk materials delivered in big bags must be transferred to packaging machines without interruption. The loading hopper of the packaging system should remain full during the filling and packaging process. Big bag discharge systems can monitor the product level in the loading hopper and maintain a constant level automatically. Depending on the packaging speed, mechanical conveying systems or pneumatic loading systems can be selected. Dust collectors can be used to prevent dust emissions during hopper loading, especially for materials with high dust content.
Mixer automation systems are used to mix dry bulk solids according to specific recipes. Raw materials delivered in FIBC bags can be transferred to mixing units through a combination of conveying equipment and bulk bag discharge systems. Depending on the type of application, pneumatic conveying or mechanical feeding systems can be used to fill mixers. Big bag discharge stations can be manufactured with built-in dosing systems. The amount of raw material to be loaded into the mixer is automatically controlled with the help of a weighing and dosing system. Dust collectors can be used to prevent dust emissions during the mixer filling process.
Bulk material stored in big bags can be automatically filled into small bags. Big bag discharge systems come with optional built-in bag filling units. For low filling capacities, these units are installed below the big bag discharge hopper, providing a practical and cost-effective solution. Both big bag discharging and bag filling operations can be handled by a single, compact system. For higher bag filling needs, bag filling machines are installed near the bulk bag discharge stations. Pneumatic conveying systems or mechanical conveyors can be used to transfer bulk material from the FIBC bag discharge station to the bag or sack filling system.
Mechanical conveyors can be used for silo loading from big bag discharge stations. Screw feeders, bucket elevators, rotary valves, or chain conveyors are connected to big bag discharge stations to fill silos. The selection of conveying equipment directly depends on the conveying distance, height, transferred material, and capacity. Bucket elevators are preferred for high silos, while screw feeders are preferred for shorter silos and short distances. The big bag discharge system can be installed on top of the silo for faster filling. In this case, rotary valves or butterfly valves are better choices as they provide simple flow control. Dust collection systems may be required depending on the dust content of the bulk solid. During silo loading, air content in the silo escapes to the atmosphere and carries some dust along with it. Vacuum fans and jet filters in dust collectors prevent dust emissions into the environment. The collected dust is sent back to the silo, thus preventing product loss.
Pneumatic conveying systems installed after bulk bag discharge units transfer bulk material through conveying pipelines to fill silos. This configuration is useful in applications where high transfer rates and long conveying distances are needed. In production lines where raw materials are stored in warehouses far from storage silos, bulk bag discharge stations can be installed close to the warehouses, and pneumatic conveying systems are used to fill silos from long distances. This design reduces the need for forklifts and cranes for bulk material transfer on the production site and increases overall efficiency.
Pneumatic conveying systems used for silo loading utilize blower pumps or compressors. Motor power, pipeline diameter, and equipment selection depend on the type of bulk material, transfer distance, silo height, and transfer capacity. Level sensors, jet filters, and other equipment are installed on storage silos to ensure the proper operation of the silo filling system.
Pneumatic conveying systems installed after bag dump units transfer bulk material through pipelines to fill silos. This configuration is ideal for applications requiring high transfer rates and long conveying distances. In production lines where raw materials are stored in warehouses far from storage silos, bag dump stations can be installed close to warehouses, allowing pneumatic conveying systems to transport materials over long distances. This design reduces the excessive use of forklifts and cranes for bulk material transfer within the production site, improving overall efficiency.
Pneumatic transfer systems used for silo loading utilize blower pumps or compressors. Motor power, pipeline diameter, and equipment selection depend on factors such as the type of bulk material, transfer distance, silo height, and transfer capacity. Level sensors, jet filters, and other equipment are installed on storage silos to ensure the proper operation of the silo filling system.
Mechanical conveyors can be used for silo loading from bag dump stations. In this configuration, screw feeders, bucket elevators, rotary valves, or chain conveyors are connected to bag dump stations to fill silos. The selection of conveying equipment depends on factors such as conveying distance, height, material properties, and capacity. Bucket elevators are preferred for high silos, while screw feeders are ideal for shorter silos and short distances. Bag dump systems can be installed on top of the silo for faster filling. In such cases, rotary valves or butterfly valves are better choices as they provide simple flow control.
Dust collection systems may be required depending on the dust content of the bulk solid. During silo loading, air inside the silo escapes to the atmosphere, carrying dust particles with it. Dust collectors equipped with a vacuum fan and jet filter capture airborne dust. The collected dust is returned to the silo, preventing product loss and ensuring a cleaner environment.
The inlet skirt is an optional feature designed to extend the lifespan of the flexible connector sleeve. Its upper portion is attached to the outlet port of the upstream equipment and extends down into the bin activator’s inlet port. The primary function of the inlet skirt is to serve as a protective shield, safeguarding the flexible connector seal from wear and damage.
A vibratory motor is externally mounted to the bin activator. When powered, the motor generates vibrations that facilitate a steady flow of dry bulk materials within the system. Depending on the application requirements, one or two vibratory motors can be installed externally.
To accommodate a bin activator, the cone of a silo must be shorter than usual, resulting in a wider outlet. A flange supplied with the bin activator is separately welded to the silo’s outlet, slightly above the opening, at the production site. Once installed, the vibrating bin discharger is securely bolted to the flange, ensuring a stable and reliable connection.
Special spring suspension links and an engineered polymer seal work together to create a flexible connection between a vibrating bin discharger and the equipment positioned above it.
The proper design and installation of the polyurethane seal prevent it from slipping off and ensure a secure seal, eliminating the risk of dry bulk material leakage. Additionally, the seal offers high stress resistance and long-term durability, withstanding stresses caused by motor vibrations, pressure conditions, and other operational factors.
Externally installed spring suspensions provide full resilience to the vibrations of the cone head. They ensure that the generated vibrations affect only the cone itself rather than the upstream equipment structure.
An internally tapered, conical-shaped baffle plate is positioned at the center of the bin activator’s diameter. The baffle is rigidly attached to the equipment body using structural steel components. It facilitates bulk material flow from upstream equipment by directly inducing vibrations into the material.
A secondary deflector plate reduces the weight of the bulk material in the lower portion of the bin activator by acting as a wedge beneath the material, directing it around the areas adjacent to the cone’s surface.
Polimak baffle plates are available in various configurations, including convex and cone plates, and in different angles (15°, 30°, 45°, or even 60°) depending on the flow characteristics of the handled bulk material and the specific application requirements.
