Alcatel Annecy ACP20 Dry Vacuum Pump (CP20) – Complete Technical Overview

The Alcatel Annecy ACP20, also designated as CP20 and identified by part number 183865, is a high-performance dry vacuum pump designed for applications requiring clean, oil‑free vacuum generation. This pump belongs to the renowned ACP (Annecy Clean Pump) series, which has been widely adopted in semiconductor manufacturing, thin‑film coating, analytical instrumentation, and research laboratories. Its multi‑stage Roots mechanism ensures reliable operation, low vibration, and consistent performance over a wide pressure range.

At the heart of the ACP20 is a two‑stage (or three‑stage, depending on configuration) dry compression system based on the Roots principle, where two figure‑eight rotors rotate in opposite directions without contacting each other or the stator. This non‑contact design eliminates the need for sealing oil or lubricants in the pumping chamber, ensuring that the evacuated gas stream remains free from hydrocarbon contamination – a critical requirement for processes like electron beam lithography, mass spectrometry, and sputter deposition.

The ACP20 delivers a nominal pumping speed of 20 m³/h (at 50 Hz) or 17 m³/h (at 60 Hz), with an ultimate pressure (partial pressure) below 5 × 10⁻² mbar (without gas ballast) and typically better than 1 × 10⁻¹ mbar with gas ballast. The compression ratio for nitrogen is exceptionally high, exceeding 10⁸, allowing the pump to operate efficiently from atmospheric pressure down to its ultimate vacuum. The pumping speed curve is relatively flat across the molecular and viscous flow regimes, ensuring fast evacuation of chambers even at low pressures.

Mechanical construction is robust and compact. The pump weighs approximately 55 kg and measures 500 mm × 200 mm × 300 mm (L × W × H), making it suitable for integration into standard equipment racks or as a standalone unit on a cart. The housing is made of cast iron with a corrosion‑resistant coating, and the rotors are precision‑balanced to minimize vibration – typically below 1.5 mm/s RMS. The motor is a three‑phase asynchronous type, rated at 1.5 kW, with built‑in thermal protection and overload relays.

Operation is straightforward with a simple on/off switch, but the pump can also be controlled remotely via an optional interface board that provides dry contact inputs for start/stop and outputs for status monitoring (running, fault, and ready signals). The pump includes an integrated gas ballast valve that can be manually opened to introduce a small flow of purge gas (e.g., nitrogen) to reduce the partial pressure of condensable vapors, thereby enhancing water vapor tolerance and preventing internal condensation during humid inlet conditions.

Cooling is achieved through a combination of forced air convection using an integrated fan and natural radiation from the finned housing. The pump is designed to operate in ambient temperatures from +5°C to +40°C with relative humidity up to 80% non‑condensing. A built‑in temperature sensor shuts down the motor if the discharge temperature exceeds 110°C, protecting the rotor seals and bearings from thermal damage. The pump's bearing life is rated at 20,000 hours under normal operation, with replaceable bearings available as a service kit.

The ACP20 is equipped with standard inlet and outlet ports: an ISO‑K DN 40 (or NW 40) flange on the inlet, and a DN 25 (NW 25) outlet, both with clamp connections for easy installation. The pump also features a pressure‑controlled vacuum isolation valve option that can be mounted directly on the inlet to prevent backstreaming in case of power failure. For exhaust gas handling, the pump includes a silencer and an optional particulate filter to capture any debris that might be entrained in the process gas.

Noise levels are exceptionally low for a dry pump of this capacity – typically below 62 dB(A) at 1 meter, thanks to the balanced rotor design and acoustically dampened housing. This makes the ACP20 suitable for use in cleanroom environments and operator‑occupied spaces without requiring additional sound enclosures. The pump's vibration signature is also minimal, avoiding interference with sensitive optical or electron beam instruments.

Maintenance is simplified by the modular design. The ACP20 requires only periodic checks of the inlet filter, gas ballast valve, and cooling fan operation. The rotor clearances are factory‑set and do not require field adjustment. Recommended preventive maintenance intervals are 10,000 hours for bearing replacement and 20,000 hours for seal inspection. The pump's design allows for easy access to the motor terminal box and the electrical junction for quick servicing.

Compliance and certifications include CE, UL, and CSA approvals for electrical safety, as well as RoHS and REACH compliance for materials. The pump meets the vacuum performance requirements of ISO 21360 and is tested for helium leak tightness to a rate of better than 1 × 10⁻⁷ mbar·L/s, ensuring that external leakage does not compromise the ultimate pressure or contaminate the process.

Typical applications for the ACP20 include backing pumps for turbomolecular pumps in SEM/TEM systems, rough pumping of load‑lock chambers, vacuum drying ovens, and as a main pump for small‑scale thin‑film deposition systems. Its oil‑free nature is particularly valued in processes where trace hydrocarbons would degrade film quality or interfere with analytical measurements. The pump is also used in glovebox systems and for evacuating helium leak detectors.

In conclusion, the Alcatel Annecy ACP20 (CP20, 183865) dry vacuum pump offers a reliable, clean, and low‑maintenance vacuum solution for a wide range of critical applications. Its advanced multi‑stage Roots technology, robust mechanical design, and user‑friendly features make it an outstanding choice for both OEM integration and laboratory use. With Alcatel's long history in vacuum engineering, the ACP20 delivers the performance and durability that demanding users expect.