Edwards nXDS Series User Manual

A735-01-880 Issue C
Page 2 © Edwards Limited 2017. All rights reserved.
Edwards and the Edwards logo are trademarks of Edwards Limited.
Introduction
1.2 ATEX directive implication
This equipment is designed to meet the requirements of Group II Category 3 equipment in accordance with Directive
94/9/EC of the European Parliament and the Council of 23rd March 1994 on the approximation of the laws of the
Member States concerning equipment and protective systems intended for use in potentially explosive atmospheres.
(The ATEX Directive).
The ATEX Category 3 applies in respect of potential ignition sources internal to the equipment. An ATEX Category has
not been assigned in respect of potential ignition sources on the outside of the equipment as the equipment has not
been designed for use where there is an external potentially explosive atmosphere.
There is no potential source of ignition within the pump during normal operation but there may be potential sources
of ignition under conditions of foreseeable and rare malfunction as defined in the Directive. Accordingly, although
the pump is designed to pump flammable materials and mixtures, operating procedures should ensure that under all
normal and reasonably foreseeable conditions, these materials and mixtures are not within explosive limits.
Category 3 is considered appropriate for the avoidance of ignition in the case of a rare malfunction which allows
flammable materials or mixtures to pass through the pump whilst within their explosive limits.
When flammable materials are present within the equipment:
 Do not allow air to enter the equipment.
 Ensure the system is leak tight.
Further details can be obtained by contacting Edwards. Refer to the address page at the back of this instruction
manual.
1.3 General description
The nXDS pump is shown in Figure 1.
The nXDS pump is a truly dry vacuum pump as all the bearings, with their hydrocarbon lubricant, are isolated from
the vacuum space. The nXDS pump is suitable for use on vapour handling processes, and may be used for some
pumping applications involving corrosive substances. For information on pumping flammable gases, contact Edwards.
The body of the pump includes a fixed scroll and an orbiting scroll. The orbiting scroll is controlled by an electric
motor through an eccentric cam on the motor drive shaft. The movement of the orbiting scroll, meshed with the
fixed scroll, forms successive crescent shaped volumes in the pump. Gas that enters the pump through the inlet is
compressed by the movement of the orbiting scroll and swept towards the centre of the fixed scroll. The compressed
gas enters the exhaust port near the centre of the fixed scroll and is exhausted from the pump through the outlet.
Refer to Section 2.1 for details of operating conditions.
1.4 Pump controller
The integral pump controller manages the supply of current to a three-phase electric motor in accordance with
operating conditions. The controller monitors power and temperature, and will protect the pump in the event of
operation under sustained high load or under fault conditions.
The controller provides the user interface (refer to Figure 1). The pump may be operated in these modes:
 Manually, using the buttons on the interface panel. Refer to Figures 2 and 9.
 Remotely via serial communications or digital and analogue process control (parallel), via the 15-way D-type
logic interface connector. Refer to Section 1.5.

Edwards nXDS Series Specifications

General

Brand	Edwards
Model	nXDS Series
Category	Water Pump
Language	English