PP/PVC Round Ventilation Duct

PP/PVC Round Ventilation Duct — Injection-Molded Seamless Construction

PP and PVC round ventilation duct is the most efficient cross-section for moving corrosive exhaust gases, offering the lowest pressure drop per unit airflow of any duct shape. XICHENG EP injection-molds round duct from DN15 to DN450 as single seamless pieces, eliminating weld seams that can leak or fail. Larger diameters (DN500-DN1500) are CNC-welded from PP sheet with full-penetration joints. According to ASHRAE fundamentals, round duct reduces friction loss by 8-12% compared to rectangular duct of equivalent cross-sectional area.

Injection-molded vs fabricated — why manufacturing method matters

Injection-molded PP duct (DN15-DN450) has uniform wall thickness at every point — no thin spots where welds might fail under negative pressure or thermal cycling. Fabricated duct (cut and welded from sheet) can have 10-15% wall thickness variation at joints. For corrosive exhaust under negative pressure (typical fume extraction), uniform wall thickness directly affects collapse resistance and long-term reliability.

Frequently Asked Questions

What diameter do I need for my airflow?

Diameter = sqrt(4 x airflow / (pi x velocity x 3600)). For 10,000 m3/h at 10 m/s: approximately 595mm = specify DN600. Undersized duct increases energy cost; oversized duct wastes material. See our duct design guide for complete methodology.

How are round duct sections joined?

Flanged connection (bolted, with gasket) is standard for most installations — allows disassembly for maintenance. Socket-weld is permanent and used where access is not required. Butt-weld joins sections end-to-end for long straight runs.

What is the maximum negative pressure PP duct can handle?

Standard wall PP duct handles -500 Pa to -1,500 Pa depending on diameter. For higher negative pressures, specify increased wall thickness or external stiffening ribs at closer spacing.