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At Rowan Food and Biomass Engineering, we have been using rotary valves for many years to deliver quality engineering to our customers. Through this, we have in-depth and first-hand knowledge of the valves we sell and are able to guide you on which products will work best for your project.
Our handy guidance below is a starting point for understanding and comparing the options available, but please contact us for more support – we’d love to discuss your needs further. Alternatively, you can also take a look at our FAQs.
What is a rotary valve?
A rotary valve is a mechanical device used to control the flow of bulk materials between two different pressure zones or levels, within in a processing or delivery system. They work by using a rotating mechanism to seal off different sections of a processing system, whilst allowing a controlled flow of materials between them. As the rotor turns, it gradually opens a chamber between two vanes, allows the inlet material to enter and as it closes, forming a rotating pocket of transit material which is isolated from the bulk.
Typically, this will look like a rotor with vanes or blades that rotate, cased within sealed housing to enable the sealing off of different sections and prevent air leakage within the flow of material. For this reason, they are often also referred to as rotary airlock valves, or simply airlock valves.
What type of rotary valve do I need?
Rotary valves are all very similar but definitely not the same! Rotary valves differ by their housing, rotor type, inlet and outlet ports, drive mechanisms, seals and more and it is important to select the right rotary valve to ensure materials are handled efficiently and flow is optimised to minimise energy consumption, material waste and wear over time.
Good materials handling leads to lower contaminator and a carefully selected rotary valve can enhance the overall output of your processing line greatly. In regulated industries, it is also necessary to select the right valve to comply with both industry standards and health and safety regulations.
Comparison Table
Scroll horizontally on the table for full details
| What is it for? | Housing Style | Feed Rates | Working Temperature | Working Pressure | Is ATEX certification available? | |
|---|---|---|---|---|---|---|
| Rotary valves are similar but not all the same. | An important consideration for the integration into your processing line. | Important to consider alongside your throughput, or how much material will be passing through the system. | Consider the suitability or impact on the material passing through. | Consider the suitability or impact on the material passing through. | This will be required if you need to protect against potentially flammable or explosive materials. | |
| Standard drop-through rotary valve | Also known as drop through rotary valves, these valves are perfect for feeding cyclones, silos, hoppers and filter housings and are perfect for when there are different pressures on each side of the valve. Like others, they do operate using an airlock system but at a lower tolerance and are therefore less suited to processes which pass into a blowline. These valves can be supplied for either circular or square inlets. | Drop through housing: A vertical configuration, where materials enter from above and exit below the valve, suiting processing lines which use gravity, without additional pressure applied. | 2 to 20 litres per revolution | 30c to 150c | -0.5bar to +0.3bar | ATEX valves available. |
| Drop through rotary Airlock Valves | Also known as rotary airlock feeders, or rotary airlock valve feeders. These are similar to the standard valves but have a higher tolerance on air leakage making them more suited for feeding conveying systems and blow lines. Unlike a blow-through valve (also designed to feed into an air stream), material is passed without additional pressure applied. | Drop through housing: A vertical configuration, where materials enter from above and exit below the valve, suiting processing lines which use gravity, without additional pressure applied. | 5 to 80 litres per revolution | -15 to + 140 Deg - C | Maximum differential pressure of 0.7 bar (11.6 PSI) | ATEX valves available. |
| Blow-through valves | This valve is specifically designed for material which passes into an airflow stream such as a blow line. Unlike the drop-through rotary airlock valve, its housing allows the valve to be integrated directly into the blow line. | Blow through housing, specifically developed for pneumatic conveying systems, facilitating material to be passed into an air stream. | 5 to 80 litres per revolution | -15 to + 140 Deg - C | Maximum differential pressure of 0.7 bar (11.6 PSI) | ATEX valves available. |
| Biomass valves | Also known as woodchip valves, these valves are ideal for the controlled discharging of wood pellets or chippings from boilers, silos or hoppers. This valve is specifically designed to be wear resistant, be able to cut through wood present in bio-fuel mixture, and to adhere to the standard required to work with wood produced fuel. | 5 to 20 litres per revolution | -15 to + 140 Deg - C | -0.5bar to +0.3bar | ATEX valves available. |
What else should I consider?
- Drive units
- RPM options
- With/without scrapers
- Mechnical seals – do they need to be high temp resistant or standard
- Rotor coating and body treatments
- Supply with/without electric motor
For more information, take a look at our FAQs, product pages, or get in touch.
