The Conveying system where the Solids to air ratio (μ=kgmaterial/kgair)is high ( < 15) is normally considered a dense phase mode of conveying. In this case, the velocity is less than the saltation velocity. Due to the above reason high conveying pressure with low air velocity is possible and suitable powders where the handling needs are for low breakage, fragile & abrasives, this system becomes an ideal solution. Dilute phase, on the other hand, is Characterized by a uniform distribution of the particles along all sections of the conveying line, with a suspension flow regime, i.e. transport velocity higher than the saltation velocity (minimum velocity to keep all material in suspension). While selecting a system one should consider some parameters like the length of the conveying system, conveying capacity, the velocity of the air and its conveying air volume, and conveying pressure. The Above system configuration plays a very crucial role in choosing the Dense and Dilute phases. The data below should be considered as stated in slide no.6 Material properties are the most important guidance as the type of conveying system depends on the material properties like particle size, density, fragile, toughness, abrasive, hardness, strength, fatigue etc. For the Dilute Phase pneumatic system materials that are free-flowing and non-abrasive are used. And for Dense Phase Pneumatic System the materials best suited that are abrasive, heavier, fragile, and have the tendency to degrade. Dilute Phase Pneumatic System consumes less energy. The Question arises which to choose among them- the answer depends on three things: material properties, conveying distance, and conveying capacity. For Long-distance conveying and high-capacity material flow Dense phase is preferred For Short-distance and low-capacity powder transfer, dilute phase are preferred. The Above points would be easy to distinguish whether to use dilute or dense phase and which one will be feasible for you Dense phase may not be as energy efficient as the Lean or Dilute phase as the compressor is used to deliver air at 6 barg.

1. Dilute Vs Dense Phase Pneumatic Conveying
System

2. Dilute Phase Conveying System

3. Dense Phase Conveying System

4. Everyone will have doubt in their mind as to what choice they should make between
the Dilute or Dense phase, even if the information is available online, but we always
have some confusion because we miss some guiding principles. So we will give you a
step-by-step approach to get the selective right system.
Between the dilute and dense phases,
which is preferable?
Dense Phase Plug flow in pipe Dilute Phase Plug flow in pipe

5. The Conveying system where the Solids to air ratio (μ=kgmaterial/kgair)is high ( < 15) is
normally considered a dense phase mode of conveying. In this case, the velocity is less
than the saltation velocity. Due to the above reason high conveying pressure with low air
velocity is possible and suitable powders where the handling needs are for low breakage,
fragile & abrasives, this system becomes an ideal solution.
The flow pattern usually is in Plug flow or moving bed type depending upon each
powder’s characteristics
1) Difference between Dilute phase and Dense Phase

6. Dilute phase, on the other hand, is Characterized by a uniform distribution of the
particles along all sections of the conveying line, with a suspension flow regime,
i.e. transport velocity higher than the saltation velocity (minimum velocity to keep
all material in suspension).
Specification Dilute Phase Pneumatic System
Dense Phase Pneumatic
System
Conveying Distance Up to 100 m Up to 500 m
Conveying velocities 15 m/s to 30 m/s Up to 12 m/s
Air pressure Below 1 bar Above 1 bar
Air Volume High Low
Solids Loading Ratio Up to 15 Ranging from 20 to 80
Conveying Capacities Up to 15 TPH Up to 80 TPH
Prime Mover
Roots Blower / Centrifugal Fans
/ Ring Channel Blowers
Compressor

8. 2) System Specifications
While selecting a system one should consider some parameters like the length of the
conveying system, conveying capacity, the velocity of the air and its conveying air
volume, and conveying pressure.
The Above system configuration plays a very crucial role in choosing the Dense and
Dilute phases. The data below should be considered as stated in slide no.6

9. 3) Material Properties
Material properties are the most important guidance as the type of conveying system
depends on the material properties like particle size, density, fragile, toughness, abrasive,
hardness, strength, fatigue etc. For the Dilute Phase pneumatic system materials that are
free-flowing and non-abrasive are used.
And for Dense Phase Pneumatic System the materials best suited that are abrasive,
heavier, fragile, and have the tendency to degrade.

10. Material Conveying System Required
Wheat flour Dilute Phase
Chemical powders Dense Phase/ Lean Phase
Alumina Dense Phase
Fly ash Dense Phase
Soda ash Dilute Phase/ Lean Phase
Coffee beans Dilute Phase
Minerals Dense Phase
Sand Dense Phase
Cereals Dilute Phase
Zinc Dust Dense Phase
PTA powder Dense Phase
Grains Dilute Phase
Sugar Dilute Phase
Micro Silica Dense Phase/ Lean Phase
Quartz Dense Phase
Titanium Dioxide (TiO2) Dense Phase/ Lean Phase

11. 4) Energy Consumption
● Dilute Phase Pneumatic System consumes less energy.
● Dense phase may not be as energy efficient as the Lean or Dilute phase as the
compressor is used to deliver air at 6 barg.

12. 5) Which to Choose- Dilute Phase or Dense?
The Question arises which to choose among them- the answer depends on three things:
material properties, conveying distance, and conveying capacity.
1. For Long-distance conveying and high-capacity material flow Dense phase is
preferred
2. For Short-distance and low-capacity powder transfer, dilute phase are preferred.
The Above points would be easy to distinguish whether to use dilute or dense phase and
which one will be feasible for you

13. 6) Let us see the advantages and disadvantages of a dilute and
dense phase conveying system over each other.
Dilute Phase Conveying Advantages:
1. Reduced Energy Consumption: Transporting the dilute phase typically requires less energy due to the lower
pressure.
2. Suitable for Soft & non-abrasive Materials: The dilute phase is often preferred for soft materials that can be
damaged by higher pressures and denser packing during dense phase transport.
Dilute Phase Conveying Disadvantages:
1. Limited distance: The transport of the dilution phase is generally suitable for shorter distances due to
the lower material-to-air ratio and the resulting need for higher air velocities.
2. Lower Conveying Efficiency: Compared to dense phase conveying, dilute phase conveying tends to
have lower conveying efficiency, which means it may not be suitable for conveying large amounts of
material quickly.

14. Dense Phase Conveying Advantages:
1. Greater Conveying Efficiency: Dense phase conveying allows larger amounts of material to be conveyed in
each batch, making it more suitable for long-distance transportation or larger volume material hauling.
2. Less Material Degradation: Because the material is transported at lower speeds and higher pressures, there is
generally less material degradation and tearing during transport.
Dense Phase Conveying Disadvantages:
1. Higher Energy Consumption: Dense-phase transport generally requires more energy because it requires
higher pressure and sometimes a larger volume of air.
2. Restricted to brittle materials: Higher pressures and the possibility of closer packing can make dense
phase transfer less suitable for very brittle materials.

15. Stratgem develops and manufactures Dilute and Dense Phase pneumatic
conveying systems based on the needs and specifications of the customer for
the product.
Stratgem Pune, India offers comprehensive services such as field service,
start-up service, full-scale material testing, and spare parts. Among the
industries we serve are food, chemicals, pharmaceuticals, plastics, minerals,
and others. To know more about the pneumatic conveying system please
feel free to connect us!

16. Contact Info.
Office No. 20, 4th Floor, B Wing, City Vista Kolte Patil Downtown, Fountain Road,
Kharadi, Pune. MH, India 411014
+91 020 46028762 | +91 9175673483
sales@stratgemprojects.com
www.stratgemprojects.com