Select the pressure-deficit or vacuum-reading calculation. Mercury-column units are inHg, cmHg, mmHg and mHg under the conventional mercury-column definition; pressure units include psi, bar, kPa and Pa.
Inches of Vacuum to psi Formula
The following formula is used to convert inches of vacuum to psi.
Variables:
- P is the positive pressure deficit below ambient in psi
- V is the mercury vacuum reading in inHg (0°C)
Multiply the inHg vacuum reading by approximately 0.491154200 to obtain the pressure deficit in psi. Equivalent gauge pressure is negative; absolute pressure equals actual ambient pressure minus this deficit.
| Inches of Vacuum (inHg) | Pressure (psi) |
|---|---|
| 1 | 0.491 |
| 2 | 0.982 |
| 3 | 1.473 |
| 5 | 2.456 |
| 7.5 | 3.684 |
| 10 | 4.912 |
| 12 | 5.894 |
| 15 | 7.367 |
| 17 | 8.350 |
| 18 | 8.841 |
| 19 | 9.332 |
| 20 | 9.823 |
| 22 | 10.805 |
| 23 | 11.297 |
| 24 | 11.788 |
| 25 | 12.279 |
| 26 | 12.770 |
| 27 | 13.261 |
| 28 | 13.752 |
| 29.92 | 14.695 |
| *Uses conventional mercury-column pressure units. Conversion: 1 inHg ≈ 0.491154 psi; 29.92 inHg ≈ 14.695 psi. | |
What is Inches of Vacuum?
Inches of vacuum is a unit of measurement used to quantify the level of vacuum pressure. It represents the difference between the atmospheric pressure and the pressure inside a vacuum system. A higher value in inches of vacuum indicates a stronger vacuum, meaning lower pressure inside the system compared to the atmospheric pressure. This measurement is commonly used in various applications, including HVAC systems, automotive engines, and laboratory equipment, to monitor and control vacuum conditions.
How to Calculate Inches of Vacuum to psi?
The following steps outline how to calculate the conversion from inches of vacuum to psi.
- First, measure the inches of vacuum (V).
- Next, use the formula P = V * (3386.389 / 6894.757293168) to calculate the pressure in psi.
- Insert the measured value of inches of vacuum into the formula and calculate the result.
- Finally, check your answer with the calculator above.
Example Problem :
Use the following variables as an example problem to test your knowledge.
Inches of Vacuum (V) = 15
Using the formula P = V * (3386.389 / 6894.757293168), the pressure deficit is approximately 7.367313 psi (equivalent gauge pressure −7.367313 psi).
