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[October 2000]
Combined Temperature and Vacuum Control Now Possible With Single Eurotherm Controller
By creating a special vacuum control function for its well-established Model 2704 Controller, Eurotherm say that complex processes like those found in vacuum heat treatment furnaces, may use a single combined functioncontroller to save cost and space. This multi-function facility will also be useful for similar vacuum related processes such as freeze dryers, autoclaves, semiconductor furnaces and CVD furnaces.
Complex heat, pressure and vacuum cycles, such as those found in advanced heat treatment furnaces, usually require the use of high specification programmers or PLCs. In such cases the temperature control function alone may be handled using one or more temperature controllers, either in cascade or single loop mode. Sometimes where vacuum bags are used, pressure can also be regulated by the same controller.
However, In addition to separate temperature and pressure control facilities, systems of this type will also usually have a dedicated vacuum control unit, designed and built to traditional standards, adding considerable cost and bulk to the equipment.
The introduction of the 2704 vacuum option has enabled Eurotherm to integrate both the temperature and vacuum control functions into one unit, providing both OEMs and heat treatment specialists with a more economic and compact control solution than they have available at present. Removing the need to buy separate expensive vacuum controllers can reduce the size of a system control PLC, or in some cases remove it completely. Eurotherm claim that the 2704 is the first DIN format temperature controller to offer this feature.
Operationally, the use of a single 2704 in this type application can offer clear advantages in processing efficiency. The unit provides provides a more informative display than more traditional vacuum control units, and in addition provides a smooth 'switchover' function between high and low vacuum levels. This function is not generally available with traditional designs of vacuum controller, a weakness which has been known to cause problems within some heat treatment processes.
The 2704 vacuum function is available in two levels: The 1-Gauge option (V1) provides an input for a single vacuum gauge, six on/off setpoints, roughing pump timeout, leak detection and a vacuum summary page. The 3-Gauge option (V3) provides all the facilities of V1 plus the facility to measure two other gauges. As part of the V3 option, one of the additional gauge inputs is directed at high vacuum gauges which need to be powered off at low vacuum in order to prevent damage to the sensor. A dedicated gauge switchover software block allows both high and low vacuum gauge inputs to be used for a 'bumpless' measurement of the chamber vacuum.
For further information Email: info@eurotherm.co.uk or go to www.eurotherm.co.uk.
ENDS