To calculate atmospheric absolute pressure, you need to understand the relationship between absolute pressure, gauge pressure, and atmospheric pressure.
Understanding the Basics
- Absolute Pressure: This is the total pressure exerted by a fluid (gas or liquid), measured relative to a perfect vacuum. A perfect vacuum has an absolute pressure of zero.
- Gauge Pressure: This is the pressure measured relative to the ambient atmospheric pressure. It’s the pressure we typically read on pressure gauges. A gauge pressure of zero indicates that the pressure is equal to the atmospheric pressure.
- Atmospheric Pressure: This is the pressure exerted by the weight of the Earth's atmosphere. It varies depending on factors like altitude and weather conditions, but is roughly around 101.325 kPa or 14.7 psi at sea level.
The Calculation
Based on the provided reference: Absolute Pressure = Gauge pressure + Atmospheric Pressure. This formula shows that to find absolute pressure, you simply add the gauge pressure to the atmospheric pressure.
Example
Let's say you have a pressure gauge reading a gauge pressure of 20 psi, and the current atmospheric pressure is 14.7 psi.
| Pressure Type | Value |
|---|---|
| Gauge Pressure | 20 psi |
| Atmospheric Pressure | 14.7 psi |
| Absolute Pressure | 34.7 psi |
So, the absolute pressure in this case would be 20 psi + 14.7 psi = 34.7 psi.
Key Takeaways
- The absolute pressure takes into account the total pressure, including the pressure of the atmosphere.
- Gauge pressure is relative to atmospheric pressure, and is often used for pressure measurements in everyday applications.
- When converting between gauge and absolute pressure, remember to add or subtract the atmospheric pressure as necessary.
