ISO/DIS 21360-4:2025

This document, in conjunction with ISO 21360-1, specifies methods for the measurement of performance characteristics of turbomolecular vacuum pumps. It is applicable to all sizes and all types of turbomolecular vacuum pumps, including those — with mechanical or magnetic bearings; — with or without an additional drag stage(s) or other pumping stages on the shaft; — with one or more inlet ports. Since turbomolecular vacuum pumps are backed by primary pumps, their performance cannot be completely defined by the volume flow rate curve. Also, the driving device and the backing pressure of the turbomolecular vacuum pump is important to the performance. The following completes the performance characteristics: — information about throughputs and backing pressure of the turbomolecular vacuum pump; — the compression ratio curve (compression ratio vs backing pressure of turbomolecular vacuum pump).