Overview
ISO 1608-1:1993 - Vapour vacuum pumps - Measurement of performance characteristics - Part 1: Measurement of volume rate of flow (pumping speed) specifies standardized methods for measuring the volume rate of flow (pumping speed) of vapour vacuum pumps. It covers diffusion pumps, ejector pumps and booster pumps (capable of operation in both molecular and laminar flow regions). The standard aims to ensure uniform test procedures and comparable performance data across manufacturers and laboratories.
Key topics and requirements
- Scope and pump types: Applies to oil- and mercury-vapour diffusion, ejector and booster pumps (with or without baffles/traps).
- Definition: Pumping speed S is defined as S = Q / P (throughput Q divided by equilibrium pressure P). Ideal gas behavior at 20 °C is assumed.
- Test method: Uses the constant-pressure method - maintain a stable pressure in a test dome while measuring gas throughput. Measurements proceed point-by-point from the lowest pressures upward (minimum five pressure points recommended).
- Test dome and geometry: A cylindrical test dome with axial dimension 1.5·D (D = internal diameter); gas inlet located on axis at distance D from the pump flange; pressure gauge connection at 0.5·D perpendicular to dome axis. The dome internal diameter equals the pump mouth or inlet plane.
- Instrumentation and accuracy: Pressure gauges calibrated to specified accuracies (e.g., ±5% for pressures ≥ 1 Pa and ±10% for lower pressures). Throughput measuring device accuracy varies by throughput range (examples in the standard: ±3% for >9.9×10⁻⁷ Pa·m³/s, ±5% for intermediate ranges, ±10% for lowest throughputs). Dry air is the default test gas.
- Test conditions: Pump must be run with specified fluid charge and heating power; ambient temperature controlled to ±1 °C (15–25 °C); allow pump/dome to reach equilibrium before recording.
- Reporting: Results graphed as pumping speed vs inlet pressure (logarithmic pressure axis, linear S axis) and throughput vs pressure (log–log), with full test-report details (gauges used, gasket type, baffles/traps and temperatures, fluid type/quantity, backing pump info, temperatures, flowrates, etc.).
Applications and users
- Manufacturers: performance characterization, product datasheets, quality control.
- Independent test laboratories: acceptance testing and certification of pumping speed.
- System designers and purchasers: compare pump performance for vacuum systems, select appropriate diffusion/ejector/booster pumps.
- R&D and maintenance teams: baseline measurements, fault diagnosis and verification after repairs or modifications.
Related standards
- ISO 1608-2: Measurement of critical backing pressure (companion part of the ISO 1608 series) - for complementary performance data.
Keywords: ISO 1608-1:1993, vapour vacuum pumps, pumping speed, measurement of volume rate of flow, diffusion pump test, ejector pump test, booster pump performance, vacuum pump testing.