· Technical review: 11 October 2026
The nXDS name identifies a pump family, but a purchase order needs more detail. A laboratory replacing an existing pump may need to retain its controls and connections. A new instrument installation needs its gas load and operating duty checked from the beginning. In either case, the full configuration matters.
1. State the pressure at the instrument
Give the pressure required where the experiment or process takes place. Ultimate pressure is a pump test figure; it is not a promise of the same pressure inside a working instrument. Include the gas flow, connecting line and any restriction between the pump and chamber.
2. Describe the whole pumping cycle
For pump-down from atmosphere, include chamber volume, evacuation time and how often the cycle repeats. For steady operation, give the normal inlet pressure and gas load. A pump that can start evacuating at atmospheric pressure does not necessarily permit continuous operation there.
The standard nXDS10i listing, for example, identifies a maximum continuous inlet pressure of 200 mbar under its specified conditions and a recommended 50-litre chamber volume for evacuation from atmosphere. Those are different pieces of information. Larger chambers need review rather than an assumption that the recommendation is an absolute capacity limit.
3. Name the gases and vapours
The standard range has gas ballast for compatible vapour duties. C and R variants serve different requirements; R variants omit gas ballast. Do not treat a suffix as an optional label. Give the supplier the actual process chemistry, including cleaning agents that may enter the pump, and identify any rare-gas recovery requirement.
4. Agree how the pump will be controlled
Local operation and integration into an instrument are different scopes. Tell us whether you need local start/stop, standby operation or a remote interface. Send the existing controller reference and wiring information when replacing equipment. Include the control cable in the quotation where required.
5. List the accessories
A useful order identifies the mains lead, inlet and exhaust connections, isolation, process protection and any exhaust treatment. Decide whether a separate gauge is needed to confirm pressure at the instrument. Dry pumping avoids sealing oil in the vacuum space, but it does not remove the need for tip-seal maintenance and access for servicing.
6. Compare the appropriate sizes
Review nXDS6i, nXDS10i, nXDS15i and nXDS20i against the same duty. Record the proposed order reference alongside each quotation so that motor, process variant and included equipment remain clear.
Discuss your equipment requirement
Our laboratory vacuum guide explains where a dedicated instrument pump fits into the wider installation. For a quotation, send your requirements to Girovac or call 01692 660 117.
Technical reference: Edwards nXDS operating instructions (PDF); Edwards nXDS range brochure (PDF). Confirm the exact model and supplied configuration when ordering.