Vacuum Measurement and control systems - Edwards^® vacuum guages

Absolute Vacuum present:
The Edwards^®range of instruments:

• Measurement over the range of 2000 to 10^-11 mbar

• Advanced microprocessor based controllers

• Calibration of instruments to UK national standards

Selecting your Edwards^® vacuum gauge

Absolute Vacuum offer a wide range of Edwards^®vacuum measurement and control products – from dial gauges to microprocessor based gauge controllers.

The first step in selecting the right gauge to meet your application is to decide the range of pressures that you want to measure at each of your measuring points. The chart below indicates the broad pressure ranges covered by the spectrum of Edwards instruments: use this chart as a primary guide to the choice of gauge head.

The second step is to establish your requirement for the output of the pressure measurement. If you simply want an indication that a certain level of vacuum has been reached (for example, to open a valve or start a process), then the vacuum switch of active gauge head alone may be appropriate. IF you want to display the pressure locally, then a dial gauge may be suitable. If your require the pressure display to be remote from the measurement point (for example, in a control panel) then select the Piriani 501, Active Gauge Display, Active Gauge Conrtoller or Active Digital Display, depending on what features you require. (You will also need to select appropriate gauge head(s) to accompany these displays and Controllers.) If you control system (such as PLC, PC or dedicated microprocessor controller) needs to know the pressure to make sequence decisions but you do not need a separate vacuum display, then you can use an Active gauge head as a stand alone transducer connected to an appropriate power supply and control system analogue input.

Thirdly, you need to select a gauge suitable for the process gases and constructed to withstand exposure to the external environment of your vacuum system. Consider both whether the gauge will survive in the process and also whether the process gases will affect the gauge's measurement. For example, the measurment made by mechanical gauges (vacuum switches, dial gauges, strain gauges and capacitance manometers) is not affected by gas composition, whereas that made by other types of guages is gas independent.

Calibration for different gases

All of the Edwards^® gauge heads are calibrated for dry nitrogen; the calibration for dry air is the same. If you use thermal conductivity or ionization gauges with gases other than nirtogen or air, you may need to apply a gas correction factor for an accurate indication of your system pressure.

Gauge head installation

How you install the gauge head into your vacuum system will affect the accuracy and reliablity of your pressure measurment. For best performance we recommend that you:

• Connect the gauge head to your vacuum system with a straight, short branch pipe.This pipe should have an internal diameter of no less than that of the gauge tube itself. Long, narrow or angled connections can cause a significant measurement error. Note that the indicated pressure may be higher or lower than the actual pressure.

• Connect the gauge head as close as possible to the point where you want to measure the system pressure

• Orientate the gauge head so that it is vertical, with the connection to the vacuum system at it's base. This prevents debris falling into the gauge.

The active gauge concept

• Operate from standard power supplies for simple installation

• Gauge type identification signal and common 0-10 T.d.c. Output

• Cable lengths of up to 100m for remote operation

• Range of microprocessor based active gauge controllers

• The active gauge range and active gauge controller give continuous measurement from 2000 mbar to 10^-11 mbar

• Low cost analogue and digital displays and controllers available

Edwards^® active vacuum gauges and controllers give unrivalled performance, flexibility and ease of use. Traditionally, vacuum gauges consisted of a sensing element and a separate display/controller. With Edwards^® active guages, the functions that are specific to the gauge type (such as signal conditioning and specialised power supplies) have been moved from the dedicated controller and incorporated in the head itself. Now the gauge head can be used as a stand alone transducer. It requires only a simple power supply and it providesa 2 to 10 V output. Alternatively, you can connect the gauges to a Edwards^® display or universal controller. These will accept all gauge types in any combination for the most flexible solution.

The Active Gauge Range

Edwards^® Active Pirani Gauge

A range of Pirani gauges including linear measuring from above atmospheric pressure to 10^-4 mbar, with integral set point for OEM use.

Edwards^® Active ION gauge

A new range of small self contained active ion gauges with a measuing range from 5x10^-2 to 5x10^-10 Torr. The gauges incorporate degas, automatic emission current switching, automatic filament protection, a pus button adjustable set point and status indicating LED.

Edwards^® Active Inverted Magnetron

Operating through the range 10^-2 mbar to 10^-9 mbar, with integral set point for OEM use. A low external magnetic active field version is available.

Edwards^® Active Wide Range Gauge

A range of gauges measuring from atmospheric to 10^-9 mbar with a linear output and integral set point for OEM use. A low external magnetic field version is available.

Edwards^® Active Thermocouple Gauge

A range of gauges measuring from atmospheric to 10^-3 mbar, with integral set point for OEM use and LED indication of vacuum status.

Edwards^® Active Strain Gauge

A range of strain gauges measuring from 2000 mbar to 1 mbar. This type of gauge is extremely rugged and offers accurate, gas independent measurement.

Edwards^® Ion Gauge Controller

The ION gauge controller can operate one or two ion gauge tubes as well as a high pressure interlocking gauge. IT has a measurement range of 5x10^-3 to 2x10^-11 mbar, with 3 levels of emission current and electronic bombardment type degas.

Edwards^® Barocel capacitance manometers

The barocel manometers provide high accuracy, high stability, gas independent pressure measurement making them ideal for a wide range of industrial process, research and calibration applications. Their Iconel/Monel construction means that they can also be used with corrosive and radioactive gases.

• Accuracy 1.15% of reading

• True total pressure measurement, independent of gas species

• Very high corrosion resistance

• Fast response

• Wide range, 4 decade range with single head

• Temperature controlled man from 45 to 123°C

• Excellent stability

The Barocel 655, 658 and 659 capacitance manometers incorporate a hermetically sealed and heated enclosure containing the pressure sensing element and critical electronic circuitry. This means that changes in ambient temperature, humidity, and atmospheric pressure have minimal effect on the reading giving excellent long term zero repeatability and stability. The 3 models ofers a choice of 45, 100 or 123°C temperature regulation.

• Full scale ranges from 0.05 Torr to 1000 Torr

• Temperature controlled

Edwards^® Active controllers and displays

The Edwards^® range of gauges can operate as stand alone pressure transducers requiring only a simple power supply and providing a 2 to 10 V analogue output. If you need a complete vacuum measuring and display system, we can also offer a range of controllers and displays.

Our displays and controllers are designed for maximum flexibility and ease of use. The range is suitable for bench-top or panel mounting and options include the RS232 iterfacing.

Edwards^®TIC Instrument Controller

A compact instrument controller with a large clear graphic display, an intuitive user interface and serial communications providing full remote control and data logging functions for one or more TIC systems via a new windows ^TM based PC program.

The controller supports and automatically recognises controls up to 3 gauges from the Edwards^®range (excluding IGC and Barocels), with coverage from 2000 to 6.6x10-¹⁰ mbar. Low pressure gauges may be controlled and protected by high pressure gauges and there are 3 open collector set point outputs. A optional replay box uses these outputs to control 3A mains changeover relays.

The TIC Instrument controller may be either rack or bench mounted and provides a useful hub for the flexible operation of a wide range of vacuum system configurations.

Edwards^®Active Gauge Controller

The Active Gauge Controller (AGC) is a universal, intelligent vacuum controller capable of operating up to 6 Active gauges in any combination. This gives vacuum measuring capability from 200mbar to 2x10^-11 mbar. The standard AGC is supplied with 6 independent set point outputs which can be controlled by any of the gauges. Outputs include RS232 connection for full remote control and single or triple gage display.

Edwards^®Active Digital Controller

The Edwards^®Active Digital Controller (ADC) is a compact single gauge controller and display. It features a bright LED display and single push button controls. The ADC automatically recognises compatible Edwards^®gauges, loads the appropriate lookup table and displays the pressure in commonly used vacuum units.

The ADC is available in standard and enhance versions. The standard controller displays the pressure measured by a single active gauge. The enhanced controller supports two similar gauges – it has two variable hysteresis set points which are linked to 48 V.d.c 1 A changeover relays and two 0.10 V.d.c analogue outputs. To aid system integration, the enhanced controller is provided with an RS232 interface.

When combined with a suitable gauge, such as the Edwards^® APGX-H Convection Pirani or Wide Range (WRG), the ADC represents a cost effective means of monitoring and controlling process vacuum in a broad range of applications.

Edwards^® Active Gauge Display

The Active Gauge Display (AGD) is a low cost controller capable of operating two Active Gauge heads (of the same type) from the following: Pirani, inverted magnetron, WRG and therm. The AGD has a clear, easy to read analogue display and is available with two optional 3A change-over relays for process control.

Edwards^® Active Digital Display

The Active Digital Display (ADD) offers control of a single Active Strain Gauge or Barocel capacitance manometer. The ADD has a clear, fout digit display with selectable pressure units. Like the Active Gauge Display, the ADD has two optional 3A change-over relays for process control.

Edwards^® 1575 Pressure Display

The model 1575 Pressure Display is a new miniature (1/8 DIN) digital pressure display and set point controller for 600, 622 and 655 capacitance manometers. The controllers are supplied with four user selectable open collector set points and push button remote zero adjustment. There are two versions, one with analogue output and the other with RS232.

Other Edwards^® Instruments

In addition to the range of Active Gauges, Edwards^® offer a variety of more traditional vacuum measurement an control products.

Edwards^®simple gauges provide rugged, local indication of pressures from atmosphere to 1 mbar and are ideal for vacuum chambers in an industrial environment. Vacuum switches, with high current ratings, give a simple method of directly controlling loads without the need for additional relays or power supplies.

The Pirani 501 display with PRE10k gauge head offers a simple, low cost solution to measurement in the range 10 to 10^-3 mbar. It is ideal for bench-top use in a labatory, or for fitting into an industrial control panel. The range of Vacustat Mcleod gauges offers traditional absolute vacuum measurement for laboratory or light industrial uses.