Gauge Pressure is the pressure measured relative to the atmospheric pressure. It represents the difference between the absolute pressure and the atmospheric pressure. In other words, gauge pressure indicates how much pressure is exerted above or below the ambient atmospheric pressure.
Here’s a bit more detail:
Definition
Gauge pressure (P gauge) is calculated as:
P gauge=P absolute−P atmospheric .
where:
P absolute is the total pressure measured (including atmospheric pressure).
P atmospheric
is the atmospheric pressure (which is approximately 101,325 Pascals at sea level).
Characteristics
Positive Gauge Pressure: When the pressure is higher than the atmospheric pressure. For example, the pressure inside a car tire is often measured in gauge pressure because it is higher than the atmospheric pressure.
Negative Gauge Pressure (or Vacuum): When the pressure is lower than the atmospheric pressure. This is often referred to as a vacuum. For example, in a vacuum chamber, the gauge pressure is negative because it is less than the atmospheric pressure.
Applications
Tire Pressure: Measured in gauge pressure to determine how much pressure is in the tire relative to the atmospheric pressure.
Pressure Cookers: Utilize gauge pressure to cook food faster by increasing the pressure inside the cooker above atmospheric pressure.
Industrial Processes: Gauge pressure is commonly used in various industrial applications to ensure systems operate within safe pressure limits.
Measurement Instruments
Manometers: Devices used to measure gauge pressure. They can be simple U-tube manometers or more complex digital pressure sensors.
Pressure Gauges: Instruments specifically designed to measure gauge pressure in various applications, from household to industrial uses.
Gauge pressure is a practical way to measure pressure in many everyday situations because it relates directly to the pressure above or below the surrounding atmospheric pressure, making it easier to understand and manage.