Helium Leak Rate Calculator
Calculate the gas leakage rate based on pressure change over time (Pressure Decay/Rise method). This tool is essential for vacuum technology and hermetic seal testing.
Calculation Results
Understanding Helium Leak Rates
Helium leak testing is the gold standard for verifying the integrity of vacuum systems, aerospace components, and industrial gas lines. Because helium is a small, inert atom, it can pass through microscopic defects that other gases might miss.
The Pressure Change Formula
This calculator uses the pressure decay or pressure rise method. The fundamental formula for calculating a leak rate (Q) is:
Q = (V × ΔP) / t
- V: Internal volume of the test object or chamber (Liters).
- ΔP: The change in pressure (mbar) during the test.
- t: The time elapsed during the measurement (Seconds).
Common Units of Measurement
In the world of leak detection, several units are used depending on the industry:
- mbar·l/s: Millibar liters per second (Common in Europe and vacuum science).
- atm·cc/s: Atmospheric cubic centimeters per second (Standard in the USA).
- Pa·m³/s: Pascal cubic meters per second (SI unit).
Example Calculation
Imagine you are testing a fuel tank with a volume of 50 Liters. After sealing the tank and waiting for 600 seconds (10 minutes), the internal pressure rises from 1013.25 mbar to 1013.35 mbar (a change of 0.1 mbar).
Using the formula:
Q = (50 L × 0.1 mbar) / 600 s = 0.00833 mbar·l/s
This equates to approximately 8.33 × 10⁻³ mbar·l/s, which might be considered a significant leak depending on the application.
When to Use This Calculator
This tool is ideal for "Accumulation Testing" or "Bombing" methods where a part is pressurized or evacuated, and the leak is measured via a physical change in pressure. For ultra-sensitive tests (below 10⁻⁶ mbar·l/s), mass spectrometer leak detectors (MSLD) are required as physical pressure changes become too small to measure reliably with standard gauges.