Answer :
To determine which units are typically used to measure static pressure, velocity pressure, and total pressure in a duct system, let's go through the options given:
A. Inches of mercury or centimeters of mercury:
- Inches or centimeters of mercury are commonly used in barometers to measure atmospheric pressure or in some vacuum applications. They are not typically used for pressures in duct systems.
B. Cubic feet per minute or cubic meters per hour:
- These units are used for measuring flow rate or volume flow, not pressure. Flow rate measures the volume of air moving through the duct per unit of time.
C. Inches of water column or centimeters of water:
- These units are commonly used to measure pressure in HVAC and duct systems. Inches of water column (in. w.c.) is a common unit of measurement for both static and velocity pressures in these systems. They measure the height of a water column that the pressure can support, which directly correlates with pressure level.
D. Pounds per square inch or kPa:
- Pounds per square inch (psi) and kilopascals (kPa) are units of pressure, but they are typically used for measuring higher pressures, like those in hydraulic systems or gas pressure. They are not commonly used in duct systems for static, velocity, or total pressure.
Based on these evaluations, the typical units used to measure static pressure, velocity pressure, and total pressure in a duct system are inches of water column or centimeters of water, which corresponds to option C.
A. Inches of mercury or centimeters of mercury:
- Inches or centimeters of mercury are commonly used in barometers to measure atmospheric pressure or in some vacuum applications. They are not typically used for pressures in duct systems.
B. Cubic feet per minute or cubic meters per hour:
- These units are used for measuring flow rate or volume flow, not pressure. Flow rate measures the volume of air moving through the duct per unit of time.
C. Inches of water column or centimeters of water:
- These units are commonly used to measure pressure in HVAC and duct systems. Inches of water column (in. w.c.) is a common unit of measurement for both static and velocity pressures in these systems. They measure the height of a water column that the pressure can support, which directly correlates with pressure level.
D. Pounds per square inch or kPa:
- Pounds per square inch (psi) and kilopascals (kPa) are units of pressure, but they are typically used for measuring higher pressures, like those in hydraulic systems or gas pressure. They are not commonly used in duct systems for static, velocity, or total pressure.
Based on these evaluations, the typical units used to measure static pressure, velocity pressure, and total pressure in a duct system are inches of water column or centimeters of water, which corresponds to option C.
