Product category:
Humidity and Environmental Sensors
News Release from: Michell Instruments | Subject: S4000 reference hygrometers
Edited by the Engineeringtalk Editorial
Team on 29 May 2003
Reference hygrometers for humidity
calibration
The validity of measurements made by industrial sensors and instruments is ensured by regular calibration, providing traceability through to a national standard.
The validity of measurements made by industrial sensors and instruments is ensured by regular calibration, providing traceability through to a national standard In other words, a field sensor must be calibrated against a reference system that itself has an unbroken chain of calibration through to some primary system, such as operated by national standards laboratories like NPL in the UK, NIST in the USA and PTB in Germany
This article was originally published on Engineeringtalk on 15 Feb 2000 at 8.00am (UK)
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Alternatively, large independent companies may operate their own primary standards in certain measurement fields such as electrical parameters, pressure etc.
Therefore there is a need for high quality, reliable and repeatable calibration reference equipment to effect the link between an industrial sensor and the primary standard.
In the field of humidity calibration, Michell Instruments has developed a variety of calibration systems that are suitable for use as a stand-alone facility to provide a high performance level and act as a transfer-standard between a primary humidity standard and the field sensor, or some other reference hygrometer.
Further reading
Latest developments in dewpoint measurement
The market is soon likely to see the introduction of a full range of humidity sensors designed to provide the exact level of function, flexibility and manual control required in each application.
Dewpointmeter monitors Millennium Seed Bank
The Royal Botanic Gardens (RBG) is using a Dewmet cooled mirror dewpointmeter from Michell Instruments to monitor equilibrium relative humidity (ERH) levels.
Michell has developed an expertise in providing such humidity calibration equipment to cover the full humidity range, from trace moisture measurement at parts-per-million levels through to relative humidity measurement at elevated temperatures.
Each system is built to customers' specific requirements.
Normally a calibration system will comprise an integrated compressor/dryer to produce a zero gas (no moisture) feed into a humidity generator and sensor housing that are designed for the user's specific needs.
The final element of calibration system is always a precision cooled mirror reference hygrometer that provides direct traceability to a primary humidity standard.
A good example is at Justervesenet, the Norwegian standards institute in Oslo.
In the absence of a primary standard within Norway, this institute decided to use two humidity calibration systems supplied by Michell Instruments, one covering the range -90 to +20C dew point and the other for the high temperature/high humidity range up to +80C dew point.
The S4000 reference hygrometers used in each system are directly calibrated at NPL.
These systems provide Justervesenet the capability to calibrate other reference hygrometers or field humidity sensors with direct traceability to a primary standard, giving the end user added confidence in humidity measurement. Request a free brochure from Michell Instruments ...
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