Product category:
Test and calibration instrumentation
News Release from: Michell Instruments | Subject: Opti-Cal
Edited by the Laboratorytalk Editorial
Team on 12 April 2004
On-site relative humidity calibration
Offers the opportunity to provide local calibration of RH sensors, without the need to send them away to a traceable laboratory or incur the cost of on-site calibration services
For the user of relative humidity sensors there is always a question over the calibration accuracy and stability of the instruments in use RH sensors provide economical measurement but require regular calibration and adjustment to ensure correct performance over extended time periods
This article was originally published on Laboratorytalk on 17 Nov 2005 at 8.00am (UK)
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Traceable laboratory humidity calibration
Stand-alone calibrator for relative humidity (RH) sensors provides humidity and temperature profiling with an inbuilt, traceable cooled mirror reference hygrometer
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.
It is common for such sensors to require calibration and adjustment at three or six month intervals, depending on the criticality of the measurement process.
Opti-Cal offers the opportunity to provide local calibration of such RH sensors, without the need to send them away to a traceable laboratory or incur the additional cost of contracted on-site calibration services.
For a relatively low capital investment, Opti-Cal will provide calibrations that are directly traceable to International Standards over a wide relative humidity range, and at any set temperature from 10 to 50C.
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.
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
Opti-Cal is a portable, fully self-contained humidity/temperature calibrator.
The system comprises a humidity/temperature controlled chamber that can house up to six or more humidity sensors, depending on their physical dimensions.
Temperature and humidity within the chamber are closed-loop controlled and continuously monitored by a precision chilled mirror reference hygrometer.
Opti-Cal works by time proportioning the flows of dry and saturated air according to the pre-selected relative humidity value.
The chamber temperature is controlled by a four-zone Peltier heat pump arrangement for maximum stability and minimum temperature gradient.
The saturator assembly can be filled easily with distilled water at the front of the unit and the easily accessible desiccator can be re-charged by heating when required.
No other maintenance is necessary.
The only external service required is a single phase power supply.
Four wire resistance thermometers for temperature and dew point measurement allow Opti-Cal to provide precise humidity and temperature reference data for the calibration of relative humidity sensors.
System accuracy of +/-0.2C dew point and +/-0.1C temperature means that an overall uncertainty to better than 2% of measured RH value is achievable.
The in-built reference cooled mirror hygrometer may be calibrated traceable to UK and US national standards and is provided as standard with Ukas certification giving conformity with EA and ILAC.
Bundled with Opti-Cal is a Windows application software suite that allows the user to monitor, chart and log calibration reference data on a PC for later manipulation.
The software also allows control of the reference hygrometer parameters for diagnosis and optimisation, and provides the capability to configure measurement units, analogue outputs and alarms. Request a free brochure from Michell Instruments ...
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