Ultimate Vacuum Test
Objective: To measure the lowest pressure a vacuum pump can achieve under no-load conditions (disconnected from the process system) after prolonged operation. This is a core indicator of the pump's pumping capacity.
Method: Seal the pump's inlet, start the pump, and let it run continuously (e.g., for 2 hours). Use a high-precision vacuum gauge to monitor and record the stable minimum pressure it can reach at the outlet.
Typical Data: The ultimate vacuum varies significantly among different types of vacuum pumps. For example, two-stage rotary vane vacuum pumps can reach the 10⁻¹ Pa level, while the ideal ultimate vacuum range for screw vacuum pumps is typically between 1×10⁻² Pa and 1×10⁻³ Pa.
Pumping Speed Test
Objective: To measure the volume of gas drawn into the pump's inlet per unit of time at a specific pressure, reflecting the pump's operational efficiency.
Method: Connect a standard vacuum chamber of known volume. Measure the time required to pump down from atmospheric pressure to a specific target pressure (e.g., 5×10⁻² mbar), and then calculate the average pumping speed.
Typical Data: Pumping speed is usually expressed in L/s or m³/h. For instance, if a pump model has a rated pumping speed of 50 m³/h, the test requirement might specify that the time to pump down from atmospheric pressure to the target pressure must not exceed 15 minutes, with a pumping speed deviation within ±5%.
Leak Rate Test
Objective: To inspect the sealing performance of the pump body and its connections, ensuring there are no obvious leaks to guarantee the stability of the ultimate vacuum.
Method: Typically, a highly sensitive helium mass spectrometer leak detector is used to inspect the entire pump (e.g., sealing areas such as the shaft end, end caps, and flanges).
Typical Data: For high-performance vacuum pumps, the overall leak rate requirement is extremely strict; for example, it must be lower than 5×10⁻⁸ Pa·m³/s.
Stability Test
Objective: To evaluate the vacuum pump's ability to maintain a specific vacuum level during continuous operation or under simulated working conditions.
Method: Run the pump continuously for an extended period (e.g., 4 hours or 168 hours) at a specific pressure, and monitor the fluctuation range of the vacuum level.
Typical Data: The vacuum level fluctuation must be minimal. For example, when running continuously at a pressure of 5×10⁻² mbar for 4 hours, the vacuum level fluctuation should not exceed ±1×10⁻³ mbar.