Gauge Pressure Sensor Basics
What is gauge pressure?
Gauge pressure is the pressure measured relative to atmospheric pressure. It can be positive or negative, depending on whether the measured pressure is above or below atmospheric pressure.
What's the difference between absolute and gauge pressure?
The difference between absolute pressure and gauge pressure lies in their reference points. Absolute pressure measures pressure relative to a perfect vacuum (zero pressure), meaning all measurements are positive. This type of pressure is crucial in scientific research and industrial processes where precise measurement is essential. On the other hand, gauge pressure measures pressure relative to atmospheric pressure, which can be either positive or negative. This is commonly used in everyday applications such as tire pressure gauges and HVAC systems. For example, if a tire gauge reads 34 psi, this is the gauge pressure. To find the absolute pressure, you would add the atmospheric pressure (approximately 14.7 psi at sea level), resulting in an absolute pressure of 48.7 psi.
How do you read gauge pressure?
To read gauge pressure, start by identifying the major units marked on the gauge, such as psi, bar, or kPa. Determine the difference between these major units to understand the scale, and count the number of smaller divisions between them to see how much each space represents. Observe where the needle points: if it points to the right of zero, it indicates positive pressure; if it points to the left, it indicates negative pressure (vacuum). If the needle points straight up, it usually means the pressure is at the zero mark, indicating atmospheric pressure. For example, if the needle points to 34 psi on a tire gauge, this is the gauge pressure. To find the absolute pressure, you would add the atmospheric pressure (approximately 14.7 psi at sea level), resulting in an absolute pressure of 48.7 psi.
When do you use a gauge pressure sensor?
A gauge pressure sensor is used when you need to measure pressure relative to the local atmospheric pressure. This type of sensor is ideal for applications where the pressure changes with atmospheric conditions, such as liquid level measurement, to monitor air pressure in heating and air conditioning systems, and in industrial processes.
