What is the pressure drop for the duct system delivering 1,000 cfm as referenced in the calculations?

To determine the pressure drop in a duct system delivering a specific airflow, such as 1,000 cubic feet per minute (cfm), various factors such as duct size, length, type, and the characteristics of the air flow must be considered.

In this case, a pressure drop of 0.25 inches of water column (IWC) suggests that this is a typical value for the resistance encountered in a well-designed duct system at that airflow rate. Based on established industry standards and calculations involving duct friction loss, a pressure drop of 0.25 IWC may occur due to common factors such as bends, transitions, and fittings that contribute to the overall static pressure loss in the system.

This value serves as a critical benchmark for HVAC systems, ensuring that the air distribution is effective while maintaining efficiency. By knowing the pressure drop, technicians can adjust the system accordingly to ensure that the blower or fan is operating effectively to overcome any losses while delivering the required airflow to the conditioned spaces.

The other choices may represent pressure drops that are either too low or too high for a system delivering 1,000 cfm, indicating that they do not align as closely with standard designs and operational parameters typically expected in industry practices.