Pressure is force distributed over a defined area and is common in all aspects of life. Our bodies are built to adapt to changing pressure levels, so the daily barometric fluctuations aren’t generally important to us. However, in industrial applications, where precise measurement is vital, experts need to consider atmospheric pressure. This is the purpose of gauge pressure.
What Is Gauge Pressure?
Gauge pressure is the mode of measuring pressure relative to atmospheric pressure. (Note that measurement modes aren’t necessarily the same as different types of pressure.) In other words, gauge pressure uses atmospheric pressureas its starting point or zero point (also called a reference point). Measuring the air in a tire is a simple, common example of measuring gauge pressure.
However, atmospheric pressure, also called barometric pressure, is not the same everywhere or even in one location. It’s largely dependent on your location’s elevation relative to sea level: Higher elevations experience lower barometric pressure, while lower elevations experience higher pressure. Weather patterns, like high- and low-pressure systems, and even sunlight can also alter local barometric pressure.
Due to its relationship with atmospheric pressure and because of the variability of atmospheric pressure, gauge pressure measurements can change based on your location’s elevation and weather patterns at the time of measurement.
Why Is Gauge Pressure Important?
Beyond its impact on our everyday lives, gauge pressure is important because of its role in industrial applications. It’s critical for guaranteeing the safety and performance of many of the systems that industries like oil and gas, waste management, and manufacturing rely on, including:
- Pneumatic and hydraulic systems: Gauge pressure regulates the function of these systems. Pressure levels help guide the operation of manufacturing equipment via the force that actuators apply. If the pressure is too high or too low, the system won’t operate with the correct precision.
- Closed systems: Perhaps the most important usage of gauge pressure is monitoring the pressure in an enclosed system. For example, water treatment facilities need to know what the pressure is in their pipes in order to ensure water flows at appropriate levels for treatment and distribution. Technicians and other staff need to maintain the pressure in pipelines like these or in storage tanks at a safe level in order to avoid leaks, failures, and explosions. To ensure these systems remain safe and functional, technicians and other facility staff need the precision that gauge pressure offers.
How Is Gauge Pressure Measured?
Gauge pressure is typically measured with a pressure gauge (digital or analog) or a pressure sensor (typically digital, though they can be analog). The exact type of device you’ll need for gauge pressure measurement depends on your industry and application. For instance, if you’re working in manufacturing automation, you’ll want to use a pressure sensor, like a transmitter or transducer; if you’re dealing with water treatment, a pressure gauge might suffice.
To ensure your gauge pressure measurement is in the correct unit, you’ll need to use the appropriate measurement system. In the U.S., people often express gauge pressure in pounds per square inch (PSI); in more scientific contexts, experts might express it in pounds per square inch gauge (PSIG). Meanwhile, the International System of Units (SI) uses the Pascal.
How Is Gauge Pressure Related to Absolute Pressure?
Absolute pressure, like gauge pressure, is a mode of pressure measurement. However, instead of using the atmospheric pressure as its reference point, absolute pressure uses a hard vacuum as its starting or zero point. What this means is a absolute pressure measurement indicate the total pressure in a system. Another way to think of absolute pressure is that it’s atmospheric pressure plus gauge pressure.
Accurate Gauge Pressure Needs Calibration
Precise gauge pressure is crucial to maintaining safety in a multitude of industrial applications. Due to ever-changing atmospheric conditions, it’s critical to make sure you properly calibrate your pressure measurement devices in order to account for the surrounding ambient pressure. Routine calibration guarantees that your pressure gauges are reading correctly.
Want to learn more about the important role that calibration plays when it comes to gauge pressure? Please explore our other resources below.