Product category:
Humidity and Environmental Sensors
News Release from: Michell Instruments | Subject: Pura
Edited by the Engineeringtalk Editorial
Team on 18 November 2002
Hygrometer finds traces in high-purity
gases
Michell Instruments has developed a rugged, self-contained hygrometer designed specifically for the measurement of trace moisture content in high-purity gases.
Michell Instruments has developed a rugged, self-contained hygrometer designed specifically for the measurement of trace moisture content in high-purity gases The Pura pure gas dew-point transmitter represents a landmark in moisture transmitter design, giving high accuracy, stability and repeatability in a specialised application, offered at a highly competitive price
This article was originally published on Engineeringtalk on 7 Oct 2003 at 8.00am (UK)
Related stories
Hygrometers gain cool calibration option
Hygrometer products from Michell Instruments are now available with traceable calibration to -90C dew point.
Moisture analyser monitors fabrication
The Pura plus is an on-line trace moisture event sensor designed for UHP inert gas applications in semiconductor fabs.
The Pura has been developed for and tested by the semiconductor industry, to measure trace moisture in the high purity gases used in the processing of silicon wafers in a semiconductor fabrication plant.
Historically trace moisture measurement has been a difficult exercise, demanding the use of complex moisture analysers or expensive analytical techniques.
The Pura provides online measurement of dew-point temperatures down to -100C, (equivalent to less than 15 parts per billion), and provides indication down even lower to -120C (less than 0.2 parts per billion).
Further reading
The smarter on-line moisture monitor
Michell Instruments has launched the high performance Cermet II hygrometer for the on-line monitoring of moisture content in a wide range of process gases.
Better measuring of moisture in natural gases
With the introduction of Promet, Michell Instruments has developed a specific solution to the issue of moisture measurement in natural gas
The Pura is suitable for large-scale integration into a semiconductor fabrication plant or high-purity gas line.
Pura is deceptively simple.
Its self-contained transmitter module has been designed to fit seamlessly into pure gas processes and give continuous and reliable measurement thereafter.
Installation is also simple.
The 0.25in male VCR gas connection ports are set at a pitch of 120mm to fit into a standard MFC footprint.
The whole unit is only 152mm in height and weighs less than 500g.
Pura provides ultimate flexibility in operation and is powered by any regulated 12 to 28V DC source.
Pura's sensor housing is fabricated from stainless steel with an internal 0.25 micron electro-polished finish for minimal moisture adsorption.
The 0.25in male VCR gas connection ports are supplied capped for cleanliness.
Pura can be delivered clean and double bagged to the class 100 clean room standard, if specified.
Furthermore, Pura is delivered fully calibrated and ready to use.
The 4-20mA output can be connected to a process indicator or centralized control system, or the RS485 text output can be used to connect directly into a suitable computer system.
Internal volumes have been designed to a minimum.
This ensures the fastest possible response speed in commissioning and also when a moisture event occurs.
The sensor body seal is rated to 1utorr, and the whole system will handle pressure right up to the VCR coupling rated maximum of 24MPa.
Whilst Pura is shipped ready to use, calibrated precisely at thirteen points across its measurement range against transfer standards traceable to NIST and NPL, it is also user-customisable.
The 4-20mA output can user set over any part of the 140C dew point range, with a minimum output span of 1C.
Also, the factory preset alarm signals, providing overrange, underrange and sensor fault conditions, can also be easily reset to suit application and system needs.
Adjustment of all these parameters is achieved through a simple PC-based user interface, supplied free of charge with every Pura on request. Request a free brochure from Michell Instruments ...
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