Which of the following is NOT one of the types of pressures found in a duct system?

In a duct system, the types of pressures measured are fundamental for understanding how air moves through the system and ensuring efficient heating, ventilation, and air conditioning (HVAC) performance. Static pressure, velocity pressure, and total pressure are well-defined measurements that play critical roles in airflow dynamics.

Static pressure is the pressure exerted by the air in the duct that is not moving, reflecting the resistance to airflow in the system. It's essential for determining how much airflow can be delivered through various components of the HVAC system.

Velocity pressure, on the other hand, is associated with the kinetic energy of the moving air. It measures the pressure due to the movement of air and is calculated based on the velocity of airflow. This pressure is crucial for understanding how fast the air is moving within the ducts and is used to ensure that the system is designed for optimal airflow rates.

Total pressure is the sum of static pressure and velocity pressure. It represents the overall pressure in the system and provides a complete picture of the energy contained in the moving air.

In contrast, thermal pressure does not exist as a defined type of pressure in a duct system. This term is not recognized in HVAC terminology, as thermal effects relate more to temperature and not directly to pressure readings in the context of