Overview
ISO/TR 16219:2020 - "Fans - System effects and system effect factors" is a Technical Report from ISO that explains how real-world ducting and fittings can degrade the air performance of fans compared with laboratory ratings (ISO 5801). It compiles experimental data (primarily from a large NEL program, plus ASHRAE- and AMCA-supported studies and manufacturer results) to illustrate trends in system-induced losses and to introduce practical definitions and guidance for system effect and system effect factor (SEF).
Key topics
- Scope and intent
- Focuses on the likely degradation of fan airflow and pressure when installed under actual site conditions versus standardized test rigs.
- Provides guidance and trends rather than prescriptive, universal correction values.
- Origins of system effects
- Distinguishes between effects caused by components at the fan inlet (vortex, swirl, vena-contracta) and the fan outlet (non-uniform velocity profiles entering downstream fittings).
- Definitions
- Introduces two SEF concepts (inlet SEF and outlet SEF). The inlet SEF is defined as the relative airflow drop (Δq/q) along a system line.
- Experimental evidence
- Presents experimental setups and results for axial, centrifugal, and mixed-flow fans, showing measured trends and sensitivities.
- Mitigation guidance
- Practical advice on reducing system effects: improved inlet/outlet connections, reducing swirl and non‑uniform flow, avoiding inlet blockage and insufficient duct length.
- Supporting material
- Informative annexes on representation of fan performance and fan-system calculation methods.
Applications and users
Who benefits from ISO/TR 16219:
- HVAC and ventilation engineers - assessing realistic fan performance and selecting fans for systems.
- System designers and ductwork engineers - specifying inlet/outlet fittings and required straight-run lengths to minimize performance loss.
- Fan manufacturers and test laboratories - understanding sensitivity of different fan types to installation effects.
- Commissioning and maintenance teams - diagnosing poor field performance and deciding retrofit or corrective measures.
Practical uses include fan selection, energy-efficiency assessments, troubleshooting under‑performance, and validating system pressure calculations with realistic SEF considerations.
Related standards
- ISO 5801 - laboratory methods for fan performance testing (referenced as the baseline for test conditions).
- AMCA 210 and ASHRAE Handbook materials - commonly used laboratory/test references cited in the report.
ISO/TR 16219 is a practical, evidence-based resource for anyone needing to account for installation-induced fan performance losses and to apply realistic correction guidance during design, specification and commissioning.