vacuümvolume

Vacuümvolume, or vacuum volume, is the interior space of a vessel or system that can be evacuated to low pressure. It is commonly expressed in liters (L) or cubic meters (m^3) and is determined by the geometry of the chamber. The vacuum volume is a fundamental parameter in vacuum technology because it sets the amount of gas that must be removed to reach a target pressure and, together with the pumping speed, governs pump-down time.

During pump-down, the pressure in the volume evolves according to the effective pumping speed S_eff and the volume V. An approximate relation is t ≈ (V/S_eff) ln(P0/Pf), where P0 is the initial pressure and Pf is the final pressure. S_eff accounts for the pump’s capacity and the conductance of piping, valves, and components between the pump and the chamber.

Outgassing from surface materials within the vacuum volume introduces additional gas that must be pumped away. Materials with low outgassing, surface treatments, and bake-out procedures can reduce this load. The vacuum volume therefore interacts with design choices about materials, seals, and processing conditions.

Applications range from laboratory vacuum chambers used in mass spectrometry or electron microscopy to large industrial vacuum vessels used in coating, drying, or metallurgical processes. Typical vacuum volumes vary from a few liters for small experiments to several cubic meters in bigger systems.

Measuring the vacuum volume is straightforward at the design stage from geometry, but practical verification may be done through commissioning tests and pressure-time data to validate pumping performance.