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Cyclone 50% Collection Efficiency for Particle Diameter

Environmental Engineering · FE Reference Handbook section

Environmental Engineering
8 formulas
10 exam-style examples
~60 min
All Environmental Engineering lectures

Core formulas for this FE topic

Definitions, applicability, units, assumptions and worked examples for each relation.

Worked exam-style examples

The four ways this section is written on the real exam — thoughts first, then equations, then substitution.

Example 1
Cyclone 50% Collection Efficiency — solve for cut diameter (50% efficiency) — Cyclone 50% Collection Efficiency for Particle Diameter

cyclone collector sized for a 50% collection efficiency cut diameter Given gas viscosity (mu) = 0.0000 Pa*s; inlet width (W) = 0.7200 m; effective turns (N_e) = 6.0000; inlet gas velocity (V_i) = 12.0000 m/s; particle density (rho_p) = 2,970 kg/m^3; gas density (rho) = 1.0900 kg/m^3, determine the cut diameter (50% efficiency) (d_p50) in m.

Given

  • gasviscosity(mu)=0.0000Pa∗sgas viscosity (mu) = 0.0000 Pa*s
  • inletwidth(W)=0.7200minlet width (W) = 0.7200 m
  • effectiveturns(Ne)=6.0000effective turns (N_e) = 6.0000
  • inlet gas velocity (V_i) = 12.0000 m/s

  • particledensity(rhop)=2,970kg/m3particle density (rho_p) = 2,970 kg/m^3
  • gasdensity(rho)=1.0900kg/m3gas density (rho) = 1.0900 kg/m^3

Find

cut diameter (50% efficiency) (d_p50), in m

Start with the thinking

  • The governing relation printed in this handbook section is Cyclone 50% Collection Efficiency.
  • Everything except d_p50 is given, so isolate d_p50 symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Cyclone 50% collection efficiency defines the cut diameter at which the cyclone collects 50% of particles of that size.

Step-by-step solution

  1. Step 1 — State the governing relation:

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9 \mu W}{2\pi N_e V_i (\rho_p - \rho)}}
  2. Step 2 — Rearrange symbolically for d_p50:

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9\mu W}{2\pi N_e V_i(\rho_p-\rho)}}
  3. Step 3 — List the givens: gas viscosity (mu) = 0.0000 Pa*s, inlet width (W) = 0.7200 m, effective turns (N_e) = 6.0000, inlet gas velocity (V_i) = 12.0000 m/s, particle density (rho_p) = 2,970 kg/m^3, gas density (rho) = 1.0900 kg/m^3.

  4. Step 4 — Substitute the given values:

    dp50=90.00000.72002πNeVi(ρp−1.0900)d_{p50} = \sqrt{\dfrac{90.0000 0.7200}{2\pi N_e V_i(\rho_p-1.0900)}}
  5. Step 5 — Evaluate:

    dp50=0.0000 md_{p50} = 0.0000\ \text{m}
  6. Step 6 — Check: returning d_p50 = 0.0000 m to

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9 \mu W}{2\pi N_e V_i (\rho_p - \rho)}}

    reproduces the given quantities, and both sides carry the same units.

Answer:
dp50=0.0000 md_{p50} = 0.0000\ \text{m}

Why the other options are there

  • 0.0000 — kept a factor of two that cancels in the correct rearrangement.
  • 0.0000 — dropped that same factor in the other direction.
  • 0.0000 — rounded an intermediate value before the final step.

Reference: FE Handbook — Cyclone 50% Collection Efficiency

Example 2
Cyclone 50% Collection Efficiency — solve for inlet gas velocity — Cyclone 50% Collection Efficiency for Particle Diameter (2)

cyclone dust collector 50% efficiency particle size determination Given gas viscosity (mu) = 0.0000 Pa*s; inlet width (W) = 0.1400 m; effective turns (N_e) = 9.5000; particle density (rho_p) = 2,900 kg/m^3; gas density (rho) = 1.2100 kg/m^3; cut diameter (50% efficiency) (d_p50) = 0.0000 m, determine the inlet gas velocity (V_i) in m/s.

Given

  • gasviscosity(mu)=0.0000Pa∗sgas viscosity (mu) = 0.0000 Pa*s
  • inletwidth(W)=0.1400minlet width (W) = 0.1400 m
  • effectiveturns(Ne)=9.5000effective turns (N_e) = 9.5000
  • particledensity(rhop)=2,900kg/m3particle density (rho_p) = 2,900 kg/m^3
  • gasdensity(rho)=1.2100kg/m3gas density (rho) = 1.2100 kg/m^3
  • cutdiameter(50cut diameter (50% efficiency) (d_p50) = 0.0000 m

Find

inlet gas velocity (V_i), in m/s

Start with the thinking

  • The governing relation printed in this handbook section is Cyclone 50% Collection Efficiency.
  • Everything except V_i is given, so isolate V_i symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Cyclone 50% collection efficiency defines the cut diameter at which the cyclone collects 50% of particles of that size.

Step-by-step solution

  1. Step 1 — State the governing relation:

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9 \mu W}{2\pi N_e V_i (\rho_p - \rho)}}
  2. Step 2 — Rearrange symbolically for V_i:

    Vi=9μW2πNedp502(ρp−ρ)V_{i} = \dfrac{9\mu W}{2\pi N_e d_{p50}^2(\rho_p-\rho)}
  3. Step 3 — List the givens: gas viscosity (mu) = 0.0000 Pa*s, inlet width (W) = 0.1400 m, effective turns (N_e) = 9.5000, particle density (rho_p) = 2,900 kg/m^3, gas density (rho) = 1.2100 kg/m^3, cut diameter (50% efficiency) (d_p50) = 0.0000 m.

  4. Step 4 — Substitute the given values:

    Vi=90.00000.14002πNe0.00002(ρp−1.2100)V_{i} = \dfrac{90.0000 0.1400}{2\pi N_e 0.0000^2(\rho_p-1.2100)}
  5. Step 5 — Evaluate:

    Vi=138.4 m/sV_{i} = 138.4\ \text{m/s}
  6. Step 6 — Check: returning V_i = 138.4 m/s to

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9 \mu W}{2\pi N_e V_i (\rho_p - \rho)}}

    reproduces the given quantities, and both sides carry the same units.

Answer:
Vi=138.4 m/sV_{i} = 138.4\ \text{m/s}

Why the other options are there

  • 276.7 — kept a factor of two that cancels in the correct rearrangement.
  • 69.1789 — dropped that same factor in the other direction.
  • 152.2 — rounded an intermediate value before the final step.

Reference: FE Handbook — Cyclone 50% Collection Efficiency

Example 3
Cyclone 50% Collection Efficiency — solve for inlet width — Cyclone 50% Collection Efficiency for Particle Diameter (3)

cyclone separator design targeting 50 percent collection efficiency of fly ash Given gas viscosity (mu) = 0.0000 Pa*s; effective turns (N_e) = 3.5000; inlet gas velocity (V_i) = 14.5000 m/s; particle density (rho_p) = 2,170 kg/m^3; gas density (rho) = 1.1000 kg/m^3; cut diameter (50% efficiency) (d_p50) = 0.0000 m, determine the inlet width (W) in m.

Given

  • gasviscosity(mu)=0.0000Pa∗sgas viscosity (mu) = 0.0000 Pa*s
  • effectiveturns(Ne)=3.5000effective turns (N_e) = 3.5000
  • inlet gas velocity (V_i) = 14.5000 m/s

  • particledensity(rhop)=2,170kg/m3particle density (rho_p) = 2,170 kg/m^3
  • gasdensity(rho)=1.1000kg/m3gas density (rho) = 1.1000 kg/m^3
  • cutdiameter(50cut diameter (50% efficiency) (d_p50) = 0.0000 m

Find

inlet width (W), in m

Start with the thinking

  • The governing relation printed in this handbook section is Cyclone 50% Collection Efficiency.
  • Everything except W is given, so isolate W symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Cyclone 50% collection efficiency defines the cut diameter at which the cyclone collects 50% of particles of that size.

Step-by-step solution

  1. Step 1 — State the governing relation:

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9 \mu W}{2\pi N_e V_i (\rho_p - \rho)}}
  2. Step 2 — Rearrange symbolically for W:

    W=2πNeVi(ρp−ρ)dp5029μW = \dfrac{2\pi N_e V_i (\rho_p-\rho) d_{p50}^2}{9\mu}
  3. Step 3 — List the givens: gas viscosity (mu) = 0.0000 Pa*s, effective turns (N_e) = 3.5000, inlet gas velocity (V_i) = 14.5000 m/s, particle density (rho_p) = 2,170 kg/m^3, gas density (rho) = 1.1000 kg/m^3, cut diameter (50% efficiency) (d_p50) = 0.0000 m.

  4. Step 4 — Substitute the given values:

    W=2πNeVi(ρp−1.1000)0.0000290.0000W = \dfrac{2\pi N_e V_i (\rho_p-1.1000) 0.0000^2}{90.0000}
  5. Step 5 — Evaluate:

    W=1.3064 mW = 1.3064\ \text{m}
  6. Step 6 — Check: returning W = 1.3064 m to

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9 \mu W}{2\pi N_e V_i (\rho_p - \rho)}}

    reproduces the given quantities, and both sides carry the same units.

Answer:
W=1.3064 mW = 1.3064\ \text{m}

Why the other options are there

  • 2.6127 — kept a factor of two that cancels in the correct rearrangement.
  • 0.6532 — dropped that same factor in the other direction.
  • 1.4370 — rounded an intermediate value before the final step.

Reference: FE Handbook — Cyclone 50% Collection Efficiency

Example 4
Cyclone 50% Collection Efficiency — solve for cut diameter (50% efficiency) (case 2) — Cyclone 50% Collection Efficiency for Particle Diameter (4)

cyclone collector sized for a 50% collection efficiency cut diameter Given gas viscosity (mu) = 0.0000 Pa*s; inlet width (W) = 0.4700 m; effective turns (N_e) = 5.5000; inlet gas velocity (V_i) = 21.0000 m/s; particle density (rho_p) = 2,990 kg/m^3; gas density (rho) = 1.0700 kg/m^3, determine the cut diameter (50% efficiency) (d_p50) in m.

Given

  • gasviscosity(mu)=0.0000Pa∗sgas viscosity (mu) = 0.0000 Pa*s
  • inletwidth(W)=0.4700minlet width (W) = 0.4700 m
  • effectiveturns(Ne)=5.5000effective turns (N_e) = 5.5000
  • inlet gas velocity (V_i) = 21.0000 m/s

  • particledensity(rhop)=2,990kg/m3particle density (rho_p) = 2,990 kg/m^3
  • gasdensity(rho)=1.0700kg/m3gas density (rho) = 1.0700 kg/m^3

Find

cut diameter (50% efficiency) (d_p50), in m

Start with the thinking

  • The governing relation printed in this handbook section is Cyclone 50% Collection Efficiency.
  • Everything except d_p50 is given, so isolate d_p50 symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Cyclone 50% collection efficiency defines the cut diameter at which the cyclone collects 50% of particles of that size.

Step-by-step solution

  1. Step 1 — State the governing relation:

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9 \mu W}{2\pi N_e V_i (\rho_p - \rho)}}
  2. Step 2 — Rearrange symbolically for d_p50:

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9\mu W}{2\pi N_e V_i(\rho_p-\rho)}}
  3. Step 3 — List the givens: gas viscosity (mu) = 0.0000 Pa*s, inlet width (W) = 0.4700 m, effective turns (N_e) = 5.5000, inlet gas velocity (V_i) = 21.0000 m/s, particle density (rho_p) = 2,990 kg/m^3, gas density (rho) = 1.0700 kg/m^3.

  4. Step 4 — Substitute the given values:

    dp50=90.00000.47002πNeVi(ρp−1.0700)d_{p50} = \sqrt{\dfrac{90.0000 0.4700}{2\pi N_e V_i(\rho_p-1.0700)}}
  5. Step 5 — Evaluate:

    dp50=0.0000 md_{p50} = 0.0000\ \text{m}
  6. Step 6 — Check: returning d_p50 = 0.0000 m to

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9 \mu W}{2\pi N_e V_i (\rho_p - \rho)}}

    reproduces the given quantities, and both sides carry the same units.

Answer:
dp50=0.0000 md_{p50} = 0.0000\ \text{m}

Why the other options are there

  • 0.0000 — kept a factor of two that cancels in the correct rearrangement.
  • 0.0000 — dropped that same factor in the other direction.
  • 0.0000 — rounded an intermediate value before the final step.

Reference: FE Handbook — Cyclone 50% Collection Efficiency

Example 5
Cyclone 50% Collection Efficiency — solve for inlet gas velocity (case 2) — Cyclone 50% Collection Efficiency for Particle Diameter (5)

cyclone dust collector 50% efficiency particle size determination Given gas viscosity (mu) = 0.0000 Pa*s; inlet width (W) = 0.5600 m; effective turns (N_e) = 7.0000; particle density (rho_p) = 2,000 kg/m^3; gas density (rho) = 1.0700 kg/m^3; cut diameter (50% efficiency) (d_p50) = 0.0000 m, determine the inlet gas velocity (V_i) in m/s.

Given

  • gasviscosity(mu)=0.0000Pa∗sgas viscosity (mu) = 0.0000 Pa*s
  • inletwidth(W)=0.5600minlet width (W) = 0.5600 m
  • effectiveturns(Ne)=7.0000effective turns (N_e) = 7.0000
  • particledensity(rhop)=2,000kg/m3particle density (rho_p) = 2,000 kg/m^3
  • gasdensity(rho)=1.0700kg/m3gas density (rho) = 1.0700 kg/m^3
  • cutdiameter(50cut diameter (50% efficiency) (d_p50) = 0.0000 m

Find

inlet gas velocity (V_i), in m/s

Start with the thinking

  • The governing relation printed in this handbook section is Cyclone 50% Collection Efficiency.
  • Everything except V_i is given, so isolate V_i symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Cyclone 50% collection efficiency defines the cut diameter at which the cyclone collects 50% of particles of that size.

Step-by-step solution

  1. Step 1 — State the governing relation:

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9 \mu W}{2\pi N_e V_i (\rho_p - \rho)}}
  2. Step 2 — Rearrange symbolically for V_i:

    Vi=9μW2πNedp502(ρp−ρ)V_{i} = \dfrac{9\mu W}{2\pi N_e d_{p50}^2(\rho_p-\rho)}
  3. Step 3 — List the givens: gas viscosity (mu) = 0.0000 Pa*s, inlet width (W) = 0.5600 m, effective turns (N_e) = 7.0000, particle density (rho_p) = 2,000 kg/m^3, gas density (rho) = 1.0700 kg/m^3, cut diameter (50% efficiency) (d_p50) = 0.0000 m.

  4. Step 4 — Substitute the given values:

    Vi=90.00000.56002πNe0.00002(ρp−1.0700)V_{i} = \dfrac{90.0000 0.5600}{2\pi N_e 0.0000^2(\rho_p-1.0700)}
  5. Step 5 — Evaluate:

    Vi=0.7962 m/sV_{i} = 0.7962\ \text{m/s}
  6. Step 6 — Check: returning V_i = 0.7962 m/s to

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9 \mu W}{2\pi N_e V_i (\rho_p - \rho)}}

    reproduces the given quantities, and both sides carry the same units.

Answer:
Vi=0.7962 m/sV_{i} = 0.7962\ \text{m/s}

Why the other options are there

  • 1.5924 — kept a factor of two that cancels in the correct rearrangement.
  • 0.3981 — dropped that same factor in the other direction.
  • 0.8758 — rounded an intermediate value before the final step.

Reference: FE Handbook — Cyclone 50% Collection Efficiency

Example 6
Cyclone 50% Collection Efficiency — solve for inlet width (case 2) — Cyclone 50% Collection Efficiency for Particle Diameter (6)

cyclone separator design targeting 50 percent collection efficiency of fly ash Given gas viscosity (mu) = 0.0000 Pa*s; effective turns (N_e) = 7.5000; inlet gas velocity (V_i) = 14.5000 m/s; particle density (rho_p) = 1,630 kg/m^3; gas density (rho) = 1.1000 kg/m^3; cut diameter (50% efficiency) (d_p50) = 0.0000 m, determine the inlet width (W) in m.

Given

  • gasviscosity(mu)=0.0000Pa∗sgas viscosity (mu) = 0.0000 Pa*s
  • effectiveturns(Ne)=7.5000effective turns (N_e) = 7.5000
  • inlet gas velocity (V_i) = 14.5000 m/s

  • particledensity(rhop)=1,630kg/m3particle density (rho_p) = 1,630 kg/m^3
  • gasdensity(rho)=1.1000kg/m3gas density (rho) = 1.1000 kg/m^3
  • cutdiameter(50cut diameter (50% efficiency) (d_p50) = 0.0000 m

Find

inlet width (W), in m

Start with the thinking

  • The governing relation printed in this handbook section is Cyclone 50% Collection Efficiency.
  • Everything except W is given, so isolate W symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Cyclone 50% collection efficiency defines the cut diameter at which the cyclone collects 50% of particles of that size.

Step-by-step solution

  1. Step 1 — State the governing relation:

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9 \mu W}{2\pi N_e V_i (\rho_p - \rho)}}
  2. Step 2 — Rearrange symbolically for W:

    W=2πNeVi(ρp−ρ)dp5029μW = \dfrac{2\pi N_e V_i (\rho_p-\rho) d_{p50}^2}{9\mu}
  3. Step 3 — List the givens: gas viscosity (mu) = 0.0000 Pa*s, effective turns (N_e) = 7.5000, inlet gas velocity (V_i) = 14.5000 m/s, particle density (rho_p) = 1,630 kg/m^3, gas density (rho) = 1.1000 kg/m^3, cut diameter (50% efficiency) (d_p50) = 0.0000 m.

  4. Step 4 — Substitute the given values:

    W=2πNeVi(ρp−1.1000)0.0000290.0000W = \dfrac{2\pi N_e V_i (\rho_p-1.1000) 0.0000^2}{90.0000}
  5. Step 5 — Evaluate:

    W=4.5467 mW = 4.5467\ \text{m}
  6. Step 6 — Check: returning W = 4.5467 m to

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9 \mu W}{2\pi N_e V_i (\rho_p - \rho)}}

    reproduces the given quantities, and both sides carry the same units.

Answer:
W=4.5467 mW = 4.5467\ \text{m}

Why the other options are there

  • 9.0933 — kept a factor of two that cancels in the correct rearrangement.
  • 2.2733 — dropped that same factor in the other direction.
  • 5.0013 — rounded an intermediate value before the final step.

Reference: FE Handbook — Cyclone 50% Collection Efficiency

Example 7
Cyclone 50% Collection Efficiency — solve for cut diameter (50% efficiency) (case 3) — Cyclone 50% Collection Efficiency for Particle Diameter (7)

cyclone collector sized for a 50% collection efficiency cut diameter Given gas viscosity (mu) = 0.0000 Pa*s; inlet width (W) = 0.6300 m; effective turns (N_e) = 4.0000; inlet gas velocity (V_i) = 23.5000 m/s; particle density (rho_p) = 2,600 kg/m^3; gas density (rho) = 1.2400 kg/m^3, determine the cut diameter (50% efficiency) (d_p50) in m.

Given

  • gasviscosity(mu)=0.0000Pa∗sgas viscosity (mu) = 0.0000 Pa*s
  • inletwidth(W)=0.6300minlet width (W) = 0.6300 m
  • effectiveturns(Ne)=4.0000effective turns (N_e) = 4.0000
  • inlet gas velocity (V_i) = 23.5000 m/s

  • particledensity(rhop)=2,600kg/m3particle density (rho_p) = 2,600 kg/m^3
  • gasdensity(rho)=1.2400kg/m3gas density (rho) = 1.2400 kg/m^3

Find

cut diameter (50% efficiency) (d_p50), in m

Start with the thinking

  • The governing relation printed in this handbook section is Cyclone 50% Collection Efficiency.
  • Everything except d_p50 is given, so isolate d_p50 symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Cyclone 50% collection efficiency defines the cut diameter at which the cyclone collects 50% of particles of that size.

Step-by-step solution

  1. Step 1 — State the governing relation:

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9 \mu W}{2\pi N_e V_i (\rho_p - \rho)}}
  2. Step 2 — Rearrange symbolically for d_p50:

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9\mu W}{2\pi N_e V_i(\rho_p-\rho)}}
  3. Step 3 — List the givens: gas viscosity (mu) = 0.0000 Pa*s, inlet width (W) = 0.6300 m, effective turns (N_e) = 4.0000, inlet gas velocity (V_i) = 23.5000 m/s, particle density (rho_p) = 2,600 kg/m^3, gas density (rho) = 1.2400 kg/m^3.

  4. Step 4 — Substitute the given values:

    dp50=90.00000.63002πNeVi(ρp−1.2400)d_{p50} = \sqrt{\dfrac{90.0000 0.6300}{2\pi N_e V_i(\rho_p-1.2400)}}
  5. Step 5 — Evaluate:

    dp50=0.0000 md_{p50} = 0.0000\ \text{m}
  6. Step 6 — Check: returning d_p50 = 0.0000 m to

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9 \mu W}{2\pi N_e V_i (\rho_p - \rho)}}

    reproduces the given quantities, and both sides carry the same units.

Answer:
dp50=0.0000 md_{p50} = 0.0000\ \text{m}

Why the other options are there

  • 0.0000 — kept a factor of two that cancels in the correct rearrangement.
  • 0.0000 — dropped that same factor in the other direction.
  • 0.0000 — rounded an intermediate value before the final step.

Reference: FE Handbook — Cyclone 50% Collection Efficiency

Example 8
Cyclone 50% Collection Efficiency — solve for inlet gas velocity (case 3) — Cyclone 50% Collection Efficiency for Particle Diameter (8)

cyclone dust collector 50% efficiency particle size determination Given gas viscosity (mu) = 0.0000 Pa*s; inlet width (W) = 0.3700 m; effective turns (N_e) = 5.0000; particle density (rho_p) = 1,640 kg/m^3; gas density (rho) = 1.2800 kg/m^3; cut diameter (50% efficiency) (d_p50) = 0.0000 m, determine the inlet gas velocity (V_i) in m/s.

Given

  • gasviscosity(mu)=0.0000Pa∗sgas viscosity (mu) = 0.0000 Pa*s
  • inletwidth(W)=0.3700minlet width (W) = 0.3700 m
  • effectiveturns(Ne)=5.0000effective turns (N_e) = 5.0000
  • particledensity(rhop)=1,640kg/m3particle density (rho_p) = 1,640 kg/m^3
  • gasdensity(rho)=1.2800kg/m3gas density (rho) = 1.2800 kg/m^3
  • cutdiameter(50cut diameter (50% efficiency) (d_p50) = 0.0000 m

Find

inlet gas velocity (V_i), in m/s

Start with the thinking

  • The governing relation printed in this handbook section is Cyclone 50% Collection Efficiency.
  • Everything except V_i is given, so isolate V_i symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Cyclone 50% collection efficiency defines the cut diameter at which the cyclone collects 50% of particles of that size.

Step-by-step solution

  1. Step 1 — State the governing relation:

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9 \mu W}{2\pi N_e V_i (\rho_p - \rho)}}
  2. Step 2 — Rearrange symbolically for V_i:

    Vi=9μW2πNedp502(ρp−ρ)V_{i} = \dfrac{9\mu W}{2\pi N_e d_{p50}^2(\rho_p-\rho)}
  3. Step 3 — List the givens: gas viscosity (mu) = 0.0000 Pa*s, inlet width (W) = 0.3700 m, effective turns (N_e) = 5.0000, particle density (rho_p) = 1,640 kg/m^3, gas density (rho) = 1.2800 kg/m^3, cut diameter (50% efficiency) (d_p50) = 0.0000 m.

  4. Step 4 — Substitute the given values:

    Vi=90.00000.37002πNe0.00002(ρp−1.2800)V_{i} = \dfrac{90.0000 0.3700}{2\pi N_e 0.0000^2(\rho_p-1.2800)}
  5. Step 5 — Evaluate:

    Vi=0.6600 m/sV_{i} = 0.6600\ \text{m/s}
  6. Step 6 — Check: returning V_i = 0.6600 m/s to

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9 \mu W}{2\pi N_e V_i (\rho_p - \rho)}}

    reproduces the given quantities, and both sides carry the same units.

Answer:
Vi=0.6600 m/sV_{i} = 0.6600\ \text{m/s}

Why the other options are there

  • 1.3201 — kept a factor of two that cancels in the correct rearrangement.
  • 0.3300 — dropped that same factor in the other direction.
  • 0.7260 — rounded an intermediate value before the final step.

Reference: FE Handbook — Cyclone 50% Collection Efficiency

Example 9
Cyclone 50% Collection Efficiency — solve for inlet width (case 3) — Cyclone 50% Collection Efficiency for Particle Diameter (9)

cyclone separator design targeting 50 percent collection efficiency of fly ash Given gas viscosity (mu) = 0.0000 Pa*s; effective turns (N_e) = 3.5000; inlet gas velocity (V_i) = 9.5000 m/s; particle density (rho_p) = 2,460 kg/m^3; gas density (rho) = 1.0400 kg/m^3; cut diameter (50% efficiency) (d_p50) = 0.0000 m, determine the inlet width (W) in m.

Given

  • gasviscosity(mu)=0.0000Pa∗sgas viscosity (mu) = 0.0000 Pa*s
  • effectiveturns(Ne)=3.5000effective turns (N_e) = 3.5000
  • inlet gas velocity (V_i) = 9.5000 m/s

  • particledensity(rhop)=2,460kg/m3particle density (rho_p) = 2,460 kg/m^3
  • gasdensity(rho)=1.0400kg/m3gas density (rho) = 1.0400 kg/m^3
  • cutdiameter(50cut diameter (50% efficiency) (d_p50) = 0.0000 m

Find

inlet width (W), in m

Start with the thinking

  • The governing relation printed in this handbook section is Cyclone 50% Collection Efficiency.
  • Everything except W is given, so isolate W symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Cyclone 50% collection efficiency defines the cut diameter at which the cyclone collects 50% of particles of that size.

Step-by-step solution

  1. Step 1 — State the governing relation:

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9 \mu W}{2\pi N_e V_i (\rho_p - \rho)}}
  2. Step 2 — Rearrange symbolically for W:

    W=2πNeVi(ρp−ρ)dp5029μW = \dfrac{2\pi N_e V_i (\rho_p-\rho) d_{p50}^2}{9\mu}
  3. Step 3 — List the givens: gas viscosity (mu) = 0.0000 Pa*s, effective turns (N_e) = 3.5000, inlet gas velocity (V_i) = 9.5000 m/s, particle density (rho_p) = 2,460 kg/m^3, gas density (rho) = 1.0400 kg/m^3, cut diameter (50% efficiency) (d_p50) = 0.0000 m.

  4. Step 4 — Substitute the given values:

    W=2πNeVi(ρp−1.0400)0.0000290.0000W = \dfrac{2\pi N_e V_i (\rho_p-1.0400) 0.0000^2}{90.0000}
  5. Step 5 — Evaluate:

    W=6.3569 mW = 6.3569\ \text{m}
  6. Step 6 — Check: returning W = 6.3569 m to

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9 \mu W}{2\pi N_e V_i (\rho_p - \rho)}}

    reproduces the given quantities, and both sides carry the same units.

Answer:
W=6.3569 mW = 6.3569\ \text{m}

Why the other options are there

  • 12.7137 — kept a factor of two that cancels in the correct rearrangement.
  • 3.1784 — dropped that same factor in the other direction.
  • 6.9925 — rounded an intermediate value before the final step.

Reference: FE Handbook — Cyclone 50% Collection Efficiency

Example 10
Cyclone 50% Collection Efficiency — solve for cut diameter (50% efficiency) (case 4) — Cyclone 50% Collection Efficiency for Particle Diameter (10)

cyclone collector sized for a 50% collection efficiency cut diameter Given gas viscosity (mu) = 0.0000 Pa*s; inlet width (W) = 0.8600 m; effective turns (N_e) = 3.5000; inlet gas velocity (V_i) = 10.5000 m/s; particle density (rho_p) = 2,260 kg/m^3; gas density (rho) = 1.0000 kg/m^3, determine the cut diameter (50% efficiency) (d_p50) in m.

Given

  • gasviscosity(mu)=0.0000Pa∗sgas viscosity (mu) = 0.0000 Pa*s
  • inletwidth(W)=0.8600minlet width (W) = 0.8600 m
  • effectiveturns(Ne)=3.5000effective turns (N_e) = 3.5000
  • inlet gas velocity (V_i) = 10.5000 m/s

  • particledensity(rhop)=2,260kg/m3particle density (rho_p) = 2,260 kg/m^3
  • gasdensity(rho)=1.0000kg/m3gas density (rho) = 1.0000 kg/m^3

Find

cut diameter (50% efficiency) (d_p50), in m

Start with the thinking

  • The governing relation printed in this handbook section is Cyclone 50% Collection Efficiency.
  • Everything except d_p50 is given, so isolate d_p50 symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Cyclone 50% collection efficiency defines the cut diameter at which the cyclone collects 50% of particles of that size.

Step-by-step solution

  1. Step 1 — State the governing relation:

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9 \mu W}{2\pi N_e V_i (\rho_p - \rho)}}
  2. Step 2 — Rearrange symbolically for d_p50:

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9\mu W}{2\pi N_e V_i(\rho_p-\rho)}}
  3. Step 3 — List the givens: gas viscosity (mu) = 0.0000 Pa*s, inlet width (W) = 0.8600 m, effective turns (N_e) = 3.5000, inlet gas velocity (V_i) = 10.5000 m/s, particle density (rho_p) = 2,260 kg/m^3, gas density (rho) = 1.0000 kg/m^3.

  4. Step 4 — Substitute the given values:

    dp50=90.00000.86002πNeVi(ρp−1.0000)d_{p50} = \sqrt{\dfrac{90.0000 0.8600}{2\pi N_e V_i(\rho_p-1.0000)}}
  5. Step 5 — Evaluate:

    dp50=0.0000 md_{p50} = 0.0000\ \text{m}
  6. Step 6 — Check: returning d_p50 = 0.0000 m to

    dp50=9μW2πNeVi(ρp−ρ)d_{p50} = \sqrt{\dfrac{9 \mu W}{2\pi N_e V_i (\rho_p - \rho)}}

    reproduces the given quantities, and both sides carry the same units.

Answer:
dp50=0.0000 md_{p50} = 0.0000\ \text{m}

Why the other options are there

  • 0.0000 — kept a factor of two that cancels in the correct rearrangement.
  • 0.0000 — dropped that same factor in the other direction.
  • 0.0000 — rounded an intermediate value before the final step.

Reference: FE Handbook — Cyclone 50% Collection Efficiency

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