Difference between Positive Pressure Ventilation Duct and Negative Pressure Ventilation Duct
Principles, Structure, and Applications Explained
—
—
—
The difference between positive pressure ventilation duct and negative pressure ventilation duct lies in their pressure characteristics, functional purposes, structural designs, and application scenarios. Understanding the difference between positive pressure ventilation duct and negative pressure ventilation duct is essential for selecting the right ventilation solution for mining, tunneling, and other engineering projects. Correct selection improves ventilation efficiency, reduces energy consumption, and minimizes maintenance costs.
1. Core Principle Differences
1.1 Pressure Characteristics
- Positive Pressure Ventilation Duct: The internal pressure is higher than atmospheric pressure. The fan forces fresh air into the target area, creating a “blowing” effect. This is a key factor in the difference between positive pressure ventilation duct and negative pressure ventilation duct.
- Negative Pressure Ventilation Duct: The internal pressure is lower than atmospheric pressure. The fan extracts contaminated air, creating a “suction” effect that passively draws in fresh air — another major aspect of the difference between positive pressure ventilation duct and negative pressure ventilation duct.
1.2 Functional Purposes
- Positive Pressure Ventilation Duct: Mainly used for directional air supply, ensuring continuous air renewal — e.g., supplying oxygen to mining work faces or tunnel construction sites.
- Negative Pressure Ventilation Duct: Focused on exhausting pollutants such as mine gas, tunnel dust, or welding fumes.
2. Structural Design Comparison
| Feature | Positive Pressure Ventilation Duct | Negative Pressure Ventilation Duct |
|---|---|---|
| Frame Structure | No frame or reinforced steel rings at both ends; flexible design | Built-in spiral spring steel wire or dense steel ring frame (66–100 per section), spaced 10–15cm to prevent collapse |
| Length & Connection | About 10m per section, easy to hang and connect | Requires segmented assembly with high sealing performance |
| Material Features | Lightweight and flexible (mainly PVC-coated fabric) | High-strength compression-resistant materials (rubber or rubber-coated fabric) |
This table clearly shows the difference between positive pressure ventilation duct and negative pressure ventilation duct in their construction.
3. Application Scenarios
Positive Pressure Ventilation Duct Applications
- Supplying oxygen in mine tunneling work faces
- Ventilating tunnel or metro construction sites
- Preventing dust infiltration in precision work zones
Advantages: Blocks pollutants, easy to maintain
Limitations: Airflow decays over long distances; possible airflow dead zones
Negative Pressure Ventilation Duct Applications
- Extracting mine gas
- Dust control in tunnel construction
- Welding workshop fume removal
Advantages: Even air mixing, no ventilation dead zones
Limitations: Requires sealed environment; weaker dust prevention
These differences in application further illustrate the difference between positive pressure ventilation duct and negative pressure ventilation duct.
4. Comprehensive Performance Comparison
| Dimension | Positive Pressure Ventilation Duct | Negative Pressure Ventilation Duct |
|---|---|---|
| Dust Control | Excellent (prevents dust infiltration) | Poorer (may draw in external dust) |
| Energy Efficiency | Low-pressure supply, low energy use | High negative pressure suction, higher energy use |
| Maintenance Cost | Simple structure, low maintenance | Complex frame, frequent sealing maintenance |
5. Selection Recommendations
When considering the difference between positive pressure ventilation duct and negative pressure ventilation duct, follow these guidelines:
- Choose Positive Pressure: When dust prevention is essential, airflow direction is specific, and the space is not fully sealed.
- Choose Negative Pressure: When removing high concentrations of pollutants or handling multiple sources of contamination.
- Hybrid Systems: Large-scale mines or tunnel projects often use positive pressure to deliver fresh air and negative pressure to exhaust contaminated air, achieving efficient circulation.
Key Parameter References:
- Positive Pressure: Maintain 15–50Pa overpressure
- Negative Pressure: Inlet air velocity of 4–5m/s for uniform airflow
6. Core Functions and Scenario Adaptation
| Criteria | Positive Pressure Ventilation Duct | Negative Pressure Ventilation Duct |
|---|---|---|
| Main Function | Directional delivery of fresh air (mine oxygen supply, smoke control) | Extraction of pollutants (dust, mine gas) |
| Pressure Feature | Internal pressure > atmospheric pressure | Internal pressure < atmospheric pressure |
| Airflow Uniformity | May have dead zones | Uniform ventilation across the area |
This comparison highlights another key difference between positive pressure ventilation duct and negative pressure ventilation duct in functional design.
7. Engineering Cost and Maintenance
| Parameter | Positive Pressure Ventilation Duct | Negative Pressure Ventilation Duct |
|---|---|---|
| Energy Efficiency | Low-pressure supply saves ~30% energy | High negative pressure suction consumes more energy |
| Dust Control | Excellent | Poorer |
| Maintenance Focus | Weekly cleaning of pre-filters | Daily cleaning of dust collectors |
| Service Life | Fan may wear faster due to dust contact | Clean inlet air can extend fan life by ~40% |
8. Conclusion
The difference between positive pressure ventilation duct and negative pressure ventilation duct comes down to airflow direction (supply vs. exhaust) and core function (dust prevention vs. pollutant removal).
- Positive Pressure Ventilation Ducts: Actively deliver fresh air, best for dust-sensitive environments like mining, tunneling, and precision engineering.
- Negative Pressure Ventilation Ducts: Actively extract polluted air, ideal for dust/fume removal and gas extraction.
For optimal results in large-scale engineering, many projects combine both systems to ensure safety, efficiency, and continuous fresh air supply.
Contact Us
🌐 Website: https://xinglianmining.com/
📧 Email: [email protected]
📞 Phone: +86 18213185860
💬 WhatsApp: +86 18214621901
📱 Facebook: https://www.facebook.com