Frictional pressure in duct systems can be defined using what?

The correct choice identifies that frictional pressure in duct systems is defined using a Friction Chart, specifically one that is provided by ASHRAE. This chart is essential for HVAC professionals as it facilitates the calculation of pressure losses in ductwork due to friction.

The ASHRAE friction chart incorporates various factors such as the type of duct material, its diameter, and airflow characteristics, allowing professionals to determine how much pressure is lost over a distance due to friction. Accurate calculations are critical in designing efficient HVAC systems, ensuring that enough air reaches the desired locations without excessive energy consumption.

While flow rate calculators, pressure drop tables, and CFM measurement devices provide useful information and assistance within the HVAC field, they do not directly define frictional pressure like the Friction Chart does. Flow rate calculators assess airflow, pressure drop tables specify losses but may not provide a comprehensive visual or systematic method for various duct sizes and materials, and CFM measurement devices simply measure airflow rather than calculating pressure loss arising from friction in the duct system. Thus, the ASHRAE Friction Chart remains the primary reference tool for determining frictional pressure in duct systems.