Rotary valves: operation, industrial applications and selection criteria

Rotary valves play a vital role in many industries by regulating the flow of bulk materials. Their unique design enables them to handle a variety of substances efficiently, from fine powders and granules to semi-viscous materials. Thanks to their precise operation, they ensure optimal flow control and effective isolation between pressure zones.

Understanding their features, specific applications and selection criteria is key to optimising industrial processes and ensuring smooth production. This article explores the characteristics of rotary valves, their uses across various sectors, and the best practices for their maintenance.

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1.1 What is a rotary valve?

A rotary valve is a mechanical device used to regulate the flow of bulk materials from one chamber to another. It consists of a rotor fitted with cavities (or pockets) that rotate within a fixed housing, allowing for precise metering of the transferred material.

1.2 Types of rotary valves

There are several types, each suited to different applications:

• Open rotor valves: ideal for lightweight, bulky materials.
• Closed rotor valves: used when tight sealing is required.
• Quick-discharge valves: designed for continuous flows and rapid batch changes.

1.3 Benefits in industrial processes

They offer several key advantages in process applications:

• Precise dosing to avoid overfeeding and improve efficiency.
• Minimised pressure leakage between separate process zones.
• Versatility in handling a wide range of materials, including dry, moist or abrasive substances.

2.1 Use in the food industry

Rotary valves are widely used in the food industry for the transport and precise dosing of materials such as flour, grains, sugar, and spices. Their hygienic design complies with strict sanitary standards and helps to minimise the risk of cross-contamination.

2.2 Role in the chemical and pharmaceutical industries

In the chemical and pharmaceutical sectors, rotary valves enable the safe handling of fine powders and sensitive granules. They provide a perfect seal to prevent leaks of volatile or hazardous substances. Some models are equipped with special coatings for resistance to corrosive materials.

2.3 Use in recycling and waste processing

Rotary valves are essential in recycling and waste treatment operations, particularly for managing fibrous materials, shredded plastics, or industrial residues. They ensure a consistent and even flow, even when handling heterogeneous materials.

3.1 Product characteristics

Selecting a rotary valve largely depends on the type of material to be processed. Key criteria include:

• Particle size: fine products require enhanced sealing, while larger granules or chunks require a suitably wide opening.
• Moisture content: some models are more suitable for moist or sticky substances.
• Abrasiveness: abrasive materials may accelerate component wear, requiring wear-resistant coatings.

3.2 Operating and environmental conditions

The environment in which the valve will operate directly impacts its suitability:

• Temperature: some models are designed to withstand extreme temperatures.
• Working pressure: valves must be suited to vacuum or pressurised systems.
• Hygiene requirements: in the food and pharmaceutical sectors, components must meet strict standards (e.g. stainless steel, easy-to-clean surfaces).

3.3 Required size and capacity

The valve's capacity must match the desired flow rate to ensure optimal performance:

• Rotor size: a larger rotor increases flow capacity, but may raise the risk of clogging.
• Number of pockets: more pockets improve flow accuracy and regulation.
• Rotation speed: can be adjusted depending on material characteristics and precision needs.

4.1 Best practices for long service life

• Regular cleaning: remove residue to prevent buildup and blockages.
• Lubrication of moving parts: ensure smooth bearing and rotor operation.
• Routine inspection: check for worn components and replace damaged parts promptly.

4.2 Common signs of wear and solutions

• Reduced flow rate: may result from blockage or rotor wear.
• Material leakage: could indicate a seal failure requiring gasket replacement.
• Unusual noises: may signal a bearing issue or misalignment.

4.3 Importance of preventive maintenance

• Planned inspections help to minimise production downtime.
• Use of original spare parts ensures optimal performance.
• Staff training promotes best maintenance practices.

5.1 What are the main functions of a rotary valve?

Rotary valves provide control over the flow of bulk materials, ensure accurate dosing, and maintain a pressure differential between different industrial zones.

5.2 Which industries use rotary valves most frequently?

They are widely used in the food, chemical, and pharmaceutical industries, as well as in recycling and waste treatment sectors, due to their versatility and ability to handle a variety of materials.

5.3 How do I choose the right rotary valve for my application?

Selection depends on several factors: type of material, operating conditions (temperature, pressure), required flow rate, and industry-specific standards. A tailored consultation with an expert is recommended to determine the ideal model.

5.4 How often should a rotary valve be maintained?

The maintenance frequency depends on the usage conditions, but a monthly inspection is recommended to ensure optimal performance.

Rotary valves are critical components for controlling flow, dosing and isolating materials in many industries. Thanks to their versatility and ability to adapt to various conditions (dry, moist, or abrasive products), they ensure a smooth, safe and efficient production process.

When well selected and properly maintained, they help reduce downtime, improve product quality and optimise overall system performance.

Need help selecting the right rotary valve for your application? Contact our expert for tailored support!