Which quantity describes the potential energy stored in the air due to pressure differences in the duct system?

Which quantity describes the potential energy stored in the air due to pressure differences in the duct system?

• A. The measurement of airflow
• B. Static Pressure
• C. Transport Velocity
• D. Capture Velocity

Answer: (B)

The main idea here is that static pressure captures the potential energy of the moving air due to pressure differences inside the duct. When air encounters resistance—such as bends, fittings, filters, or long runs—the air is pressurized against the duct walls. This pressure represents energy that could be used to push air through the system or do work on surfaces, even if the air’s speed changes along the way. In duct design and operation, static pressure is what engineers monitor to ensure there’s enough force to overcome friction and restrictions and to know how much energy is available to move air through the system. It’s helpful to contrast with related ideas: measuring airflow tells you how much air is moving (volume per time), not how much energy is stored. Transport velocity refers to the actual speed of the air in the duct, which is connected to, but distinct from, the energy stored as static pressure. Capture velocity is a concept used in air-purge or hood systems to describe the effective draw into a capture device, not the energy stored in the duct due to pressure differences.

The main idea here is that static pressure captures the potential energy of the moving air due to pressure differences inside the duct. When air encounters resistance—such as bends, fittings, filters, or long runs—the air is pressurized against the duct walls. This pressure represents energy that could be used to push air through the system or do work on surfaces, even if the air’s speed changes along the way. In duct design and operation, static pressure is what engineers monitor to ensure there’s enough force to overcome friction and restrictions and to know how much energy is available to move air through the system.

It’s helpful to contrast with related ideas: measuring airflow tells you how much air is moving (volume per time), not how much energy is stored. Transport velocity refers to the actual speed of the air in the duct, which is connected to, but distinct from, the energy stored as static pressure. Capture velocity is a concept used in air-purge or hood systems to describe the effective draw into a capture device, not the energy stored in the duct due to pressure differences.