Absolute Pressure Using Equation Of State Given Specific Weight Calculator

Formula Used:

\[ P_{ab'} = R \times S \times T \]

Gas Constant (R):

J/kg·K

Specific Weight of Liquid in Piezometer (S):

N/m³

Absolute Temperature of Gas (T):

Absolute Pressure by Specific Weight (Pab'):

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1. What is Absolute Pressure by Specific Weight?

Absolute Pressure by Specific Weight is labeled when any pressure is detected above the absolute zero of pressure. It is calculated using the equation of state for gases that relates pressure to specific weight and temperature.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ P_{ab'} = R \times S \times T \]

Where:

\( R \) — Gas Constant (J/kg·K)
\( S \) — Specific Weight of Liquid in Piezometer (N/m³)
\( T \) — Absolute Temperature of Gas (K)

Explanation: This formula calculates absolute pressure using the equation of state, where the pressure is proportional to the product of gas constant, specific weight, and absolute temperature.

3. Importance of Absolute Pressure Calculation

Details: Accurate absolute pressure calculation is crucial for various engineering applications, including fluid mechanics, thermodynamics, and pressure measurement systems where precise pressure values above absolute zero are required.

4. Using the Calculator

Tips: Enter gas constant in J/kg·K, specific weight in N/m³, and absolute temperature in Kelvin. All values must be positive and valid for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is the significance of absolute pressure?
A: Absolute pressure is measured relative to a perfect vacuum (zero pressure), making it essential for scientific calculations where precise pressure measurements are required.

Q2: How does this differ from gauge pressure?
A: Gauge pressure is measured relative to atmospheric pressure, while absolute pressure is measured relative to absolute zero pressure. Absolute pressure = Gauge pressure + Atmospheric pressure.

Q3: What are typical units for these measurements?
A: Gas constant is typically in J/kg·K, specific weight in N/m³, temperature in Kelvin, and the resulting pressure in Pascals (Pa).

Q4: When should this equation be used?
A: This equation is particularly useful in fluid mechanics and thermodynamics applications where the relationship between pressure, specific weight, and temperature needs to be determined for gases.

Q5: Are there limitations to this equation?
A: This equation assumes ideal gas behavior and may be less accurate for real gases under extreme conditions of pressure and temperature.