What is the function and how do rotary valves work?

What is the function of rotary valves?

Rotary valves are used to introduce products (powders or granules) into a high-pressure or vacuum pneumatic transport line, being used in pneumatic valves tables with the same purpose as pneumatic lines, closing and sealing the system.

They can also be applied to mechanical transport or low pressure lines for dosing products, ensuring continuous and uninterrupted flow in the operation of the plant in which it was intended.

Therefore, in short, it is the function of the rotary valve to maintain a constant flow of product fed into the system and in pneumatic transport lines it also serves to maintain its tightness.

How do rotary valves operate? Its operating principle starts from a rotor divided into multiple internal chambers where the product is housed and is continuously dosed in the direction of rotation and exit of the equipment. At least two compartments are always being fed into the equipment inlet, with one side of the valve always containing product. Its design includes its housing (valve body), a gear motor, a rotor with compartments formed by vanes around an axis and side covers to close the equipment. Another important detail is the case in which the rotary valve for pneumatic transport lines has a more robust sealing system to provide even greater sealing in the equipment.

+Rotary valve of horizontal passage

Why do rotary valves "leak"? Rotary valves are not 100% watertight and this is due to the intentional minimum internal clearances that allow the correct rotation of the valve rotor and the non-interference and wear of its components. The gaps must be machined with precision and in cases where the air return is not directed correctly and the exhaust system (filters, sleeves and exhaust fans) is incorrectly sized, it can lead to leaks, causing the trapped air to return to the supply inlet and impede flow of material due to internal pressure.

+Rotary valve of vertical passage

As can be seen, air return is normal in smaller quantities and in our dimensions of pneumatic transport lines they are already accounted for and correctly directed, thus not interfering with the correct functioning of the systems.

One of the other reasons could be the wear of parts due to use, such as worn shaft seals.

Which rotary valve design should I choose for my process?

Rotary valves have several possibilities and can be customized according to the operating needs of each client, below we will mention some ways to configure the valve to assist in an ideal choice.

• Material: You can choose between different material possibilities such as nodular cast iron, carbon steel, stainless steel and aluminum, enabling sanitary-level finishes.
• Valves: In our line of models we have different sizes to meet large and small operating capacities.
• Rotors: Rotors can have a varied number of compartments, closed or open, domed or straight, with coating on their ends and in their compartments, with different vane patterns.
• Treatments: You can change the properties of the valve by carrying out specific treatments that can increase its resistance and durability of the equipment.
• Accessories: Such as air injection into the bearings to prevent the encrustation of greasy products that are difficult to drain, injectors in pneumatic lines and hoppers already designed to filter the air return.
• Others: Reduction of valve entry and direction and the use of a “knife” for greater shear.

These and other options can be applied to define the best rotary valve for your process and application, our technical team has the necessary expertise to indicate the best option and determine what you need.

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If you have any questions about rotary valves, our team will certainly have an answer, feel free to contact us to find a valve specialist near you.

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