Cyclone Separator Calculator
Estimate cyclone inlet velocity, pressure drop, Lapple-style cut point, grade collection efficiency, fan power, and geometry ratios from airflow, inlet size, body diameter, cone length, and particle data.
Choose a known cyclone family or field application, then tune airflow, body size, pressure drop, particle size, density, and inlet dimensions.
Used with the cone to estimate residence time and active turns.
Cyclone Results
| Cyclone family | Typical inlet W x H | Outlet diameter | Body + cone length | Typical use |
|---|---|---|---|---|
| Lapple 2D2D | 0.25D x 0.50D | 0.50D | 2D body + 2D cone | General dust collection with moderate pressure drop |
| Lapple 1D3D | 0.20D x 0.50D | 0.50D | 1D body + 3D cone | Finer capture where extra cone length is available |
| Stairmand high efficiency | 0.20D x 0.50D | 0.50D | 1.5D body + 2.5D cone | Powder and process dust with strong grade efficiency |
| Stairmand high throughput | 0.375D x 0.75D | 0.75D | 1.5D body + 2.5D cone | Higher flow at lower separation sharpness |
| Swift high efficiency | 0.25D x 0.50D | 0.50D | 1.75D body + 2.5D cone | Compact industrial separators with fine dust focus |
| Swift high capacity | 0.44D x 0.80D | 0.75D | 1.25D body + 2.0D cone | Precleaner duty before filters or baghouses |
| Material | Approx density | Common particle range | Cyclone behavior |
|---|---|---|---|
| Wood dust and chips | 25 to 45 lb/ft3 | 20 to 1000 microns | Easy for coarse chips, harder for sanding fines |
| Grain dust | 35 to 55 lb/ft3 | 10 to 300 microns | Good precleaner, verify combustible dust controls |
| Cement dust | 80 to 100 lb/ft3 | 3 to 100 microns | Dense particles help, very fine fraction may pass |
| Fly ash | 40 to 90 lb/ft3 | 1 to 80 microns | Fine ash often needs high efficiency or filtration |
| Plastic powder | 55 to 75 lb/ft3 | 20 to 500 microns | Static and dust loading can affect real capture |
| Metal fines | 150 to 450 lb/ft3 | 5 to 250 microns | High density improves centrifugal separation |
| Service | Inlet velocity | Pressure drop | Design note |
|---|---|---|---|
| Woodworking cyclone | 3000 to 4500 fpm | 2 to 6 in w.g. | Keep duct transport velocity high enough for chips |
| Powder process cyclone | 3500 to 5500 fpm | 4 to 10 in w.g. | Higher velocity improves cut point but costs fan power |
| High capacity precleaner | 2500 to 4000 fpm | 1.5 to 5 in w.g. | Built for bulk removal before final filters |
| High efficiency cyclone | 4000 to 6500 fpm | 5 to 12 in w.g. | Useful for finer dust when erosion and fan power allow |
| Abrasive mineral dust | 2800 to 4500 fpm | 3 to 8 in w.g. | Use wear liners or conservative velocity when needed |
| D50 cut point | 10 micron capture | 40 micron capture | Meaning |
|---|---|---|---|
| 5 microns | About 85% | Above 99% | Strong fine dust performance for a cyclone |
| 10 microns | About 50% | Above 98% | Common high efficiency design target |
| 20 microns | About 15% | About 85% | Good for coarse process dust or chips |
| 40 microns | Under 5% | About 50% | Precleaner behavior, final filter still important |
A cyclone separator use spinning air to separate dust particles from the air that pass through the cyclone separator. The spinning air create a centrifugal force that pushes the heavier particle against the walls of the cyclone separator. The particles that hit the walls of the cyclone separator fall into a collection hopper.
The remaining air that doesnt contain much particles exits the cyclone separator. Cyclone separators has no filter media and no bags to replace so the operating costs is low (if the cyclone separator has the proper geometry). The geometry of a cyclone separator is difficult to determine without calculation.
How a Cyclone Separator Works and How to Size It
For example, a wide inlet will prevent the air from spinning inside the cyclone separator. A short cone will prevent fine particles from hitting the walls of the cyclone separator. A sizing tool will make these calculations for the operator.
Another important parameter for the cyclone separator is the inlet velocity. The velocity has to be high enough to create the centrifugal force necessary to separate the particles from the air, but too high of a velocity will erode the walls of the cyclone separator and may move some of the separated particles back into the air stream. Most cyclone separators work best at inlet velocities between 3,000 and 5,000 feet per minute.
If the velocity is too low, the cut point will be coarsely and fine particles will not be collected in the cyclone separator. If the velocity is too high, the pressure drop will be high and the fan will require more power to move the air. The sizing tool will calculate the inlet velocity based off the airflow and the inlet size of the cyclone separator.
The cut point (D50) of a cyclone separator is the size of the particles at which 50% of the particles will be captured by the cyclone separator. Particles that are larger than the D50 size will be mostly captured by the cyclone separator but particles that are smaller than the D50 size will mostly pass through the cyclone separator and exit the system as clean air. In the real world, the cut point of a cyclone separator may not match the D50 value of the particles.
Additionally, the particles entering the cyclone separator may not all be the same size or density. The operator will have to select the cut point value of the cyclone separator to ensure that it will effectively capture the particles of interest. For example, if the wood dust particles are 10 microns in size, a cut point of 20 microns will not effectively capture all of the wood dust.
The pressure drop of a cyclone separator is a measurement of how much the fan that supplies the air to the cyclone separator will have to work to move the air through the cyclone separator. The higher the pressure drop, the higher the fan will have to work. Pressure drop can be estimated with the sizing tool based on the inlet velocity and the geometry of the cyclone separator.
For instance, Stairmand cyclone separators have a more higher pressure drop than Swift cyclone separators. Additionally, the sizing tool can help the operator determine the cost to operate the different size cyclone separators. The geometry ratios of the cyclone separator have a direct effect on the cut point of the cyclone separator.
For example, the ratio of the inlet area to the body diameter, the length of the cone, and the outlet diameter each have an effect on the cut point of the cyclone separator. A longer cone will allow the particles more time to separate from the air stream and will lower the cut point. However, a longer cone will also increase the height of the cyclone separator and its cost.
A wider inlet will allow air to move through the cyclone separator at a lower velocity, but will lower the sharpness of the cut point. The density of the particles and the size distribution of the particles entering the cyclone separator are two parameters that will change based on the use of the cyclone separator. For example, metallic particles will have a higher density than particles like cement or fly ash.
The sizing tool will allow the operator to adjust these setting to account for the specific material that will be processed through the cyclone separator. Additionally, the sizing tool will ask for the category of the dust that will be processed by the cyclone separator. The loading of the dust will impact how the sizing tool variable interact with each other.
Most cyclone separators will have some form of complications in the real world that are not accounted for in the sizing tool. For instance, air may enter the cyclone separator at the inlet through leaks. Additionally, a rotary valve at the bottom of the cyclone separator where the collected material exit can reintroduce the separated particles into the air stream.
Additionally, changes in the temperature of the air will change the density of the air. This will change the inlet velocity of the air through the cyclone separator. These factors will prevent the values calculated by the sizing tool from being directly applied to the cyclone separator.
The operator should of use these calculated values as a starting point and ensure that there is some safety margin in the velocity and pressure drop calculations. Finally, there are two options for the actual cyclone separator that may be purchased for an application. Either one can purchase one large cyclone separator or several smaller cyclone separators can be purchased.
The large cyclone separator will be cheaper to purchase for the same amount of airflow. However, if several smaller cyclone separators are to be purchased, it will be possible to tune each cyclone separator for a finer cut point. Additionally, several smaller cyclone separators can be staged to handle different load.
The operator can use the sizing tool to calculate the differences in cost and performance between the two options.
