Introduction to Crosses in Spiral Duct Systems

In HVAC systems, managing airflow and dividing it into different paths is one of the most important stages of design. The spiral duct cross serves as a vital connection, providing the possibility for airflow to be directed from one main path to four different paths or for four ducts to connect at a single point. This connection is widely used in complex ventilation networks and main risers.
Using the appropriate cross ensures that the airflow is guided to the branches in a balanced manner without causing severe pressure drops or unwanted turbulence.

Applications of Spiral Duct Crosses

Crosses are used in various parts of the ventilation system, including:

• Dividing airflow into multiple different paths
• Connecting four ducts to a central point
• Uniform distribution of air flow rate in complex networks
• Connecting risers and sub-branches to the main duct
• Designing large and industrial ventilation networks

In professional projects, the correct selection of the cross plays an important role in the efficiency and lifespan of the ventilation system.

Types of Spiral Duct Crosses

Spiral duct crosses are divided into several types based on structure and application:

Standard Cross (Equal Diameter)
In this type, the diameter of all branches is the same, and the axes of the ducts are aligned.
Advantages:

• Uniform distribution of airflow
• Low pressure drop
• Suitable for straight paths and standard networks

Reducing Cross
In reducing crosses, the diameter of the branches differs from one another. This type of cross, in addition to dividing the flow, provides the possibility of changing the duct diameter at the connection point.
Applications:

• Adapting ducts to architectural limitations
• Managing air flow rate in different branches
• Improving pressure balance in the system

Advantages of Using Crosses and Reducing Crosses

Using standard and reducing crosses offers numerous benefits:

• Uniform air distribution between branches
• Reduced system pressure drop
• Prevention of noise generation in the flow path
• Complete compatibility with system engineering design
• Reduced fan energy consumption
• Fast and easy installation

In large projects, using a reducing cross instead of several separate connections is very cost-effective both technically and economically.

Material and Composition of Spiral Duct Crosses

Crosses and reducing crosses are usually manufactured from the following materials:

• Galvanized steel sheet (most common option)
• Stainless steel sheet (for special and industrial environments)
• Aluminum sheet (lightweight and resistant)

Galvanized sheet is the primary choice in most projects due to its corrosion resistance, high durability, and suitable price.

Impact of Cross Design on System Performance

Non-standard crosses can cause serious problems in the system:

• Severe pressure drop
• Unbalanced air distribution
• Increased energy consumption
• Creation of annoying noise in the duct

Conversely, standard spiral crosses with engineered design guide the airflow in a controlled and uniform manner.

Important Considerations in Choosing Crosses and Reducing Crosses

To choose the appropriate cross, attention must be paid to the following:

• Diameter of ducts (inlet and outlet)
• Type of cross (standard or reducing)
• Length and angle of branches
• Installation space
• Project usage type
• Manufacturing quality and sealing

Specialized consultation before purchase prevents execution problems and additional costs.

Application of Crosses in Different Projects

Crosses and reducing crosses are used in diverse projects:

• Residential buildings and office complexes
• Commercial and retail centers
• Hospitals and medical centers
• Factories and industrial sheds
• Large halls, conference halls, and warehouses

In all these projects, the correct choice of cross has a direct impact on the quality and efficiency of the ventilation system.

Conclusion

The spiral duct cross and reducing crosses are vital connections in HVAC systems that play an important role in dividing airflow, uniform distribution, and maintaining pressure balance. Using standard and high-quality crosses increases system efficiency, reduces pressure drop, and improves the overall performance of the ventilation network. Kian Fan offers various types of spiral duct crosses and reducing crosses with high quality and in accordance with modern standards to professionally meet the needs of different ventilation projects.