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5.11
A
Technical article on General Humidity - Humidity Definitions, Details on
Relative or Absolute Humidity, Practical Requirements of Humidy Measurement,
State of the Technology and functional principles - from Vereta
Notes
on Relative Humidity- from the University of Illinois.
Atmospheric
Moisture - Sample chapter from the textbook
Meteorology Today by C. Donald Ahrens. (PDF 1.5MB 22 pages)-Thanks
to www.novalynx.coHumidity
Sensors for Industrial Applications - This paper reviews various humidity
sensor technologies and their typical applications in context of the measurement
ranges to which they are best suited. The effects of contamination, highly
significant in view of the analytical nature of the measurement, are briefly
assessed. In conclusion, it is suggested that, if initial cost is not the prime
consideration, the chilled mirror, optical dew point hygrometer offer the most
accurate, repeatable and reliable method of humidity measurement with the widest
possible range - from Able Instruments and Controls - from Michell Instruments.
Cooled
Mirror Sensor Technology - The optical condensation principle of dew point
measurement has been established for centuries as the most fundamental method of
determining the moisture content of a gas. The dewpoint temperature (that is,
the temperature at which water vapour begins to condense to liquid or ice as the
gas is cooled) describes precisely the moisture concentration of the gas. The
major uncertainties in this measurement are related to the instantaneous
detection of the on-set of condensation and the accuracy to which the
temperature of the condensing surface can be measured. Early manual dew-point
hygrometers suffered inaccuracies due to their cyclical nature, being cooled by
an external coolant such as carbon dioxide or by the evaporation of a solvent,
and also because of the time taken to produce an observable layer of condensate,
often leading to an underestimation of the moisture content. The modern,
automatic cooled mirror sensor addresses these deficiencies and also provides an
instrument that is rugged and reliable enough to be applied to process control
measurement as well as laboratory use - from Michell Instruments.
Moisture
Sensor for the Measurement of Absolute Humidity in Process Air and Gases -
This latest generation impedance dewpoint sensor
combines fast response and high repeatability with long-term
stability and resistance to contamination - from Michell Instruments.
The following technical papers are from gesensing
An
Intercomparison of a Two-Pressure/Two-Temperature Frost Point Generator and
Chilled Mirror Condensation Hygrometer
Humilab
Benchtop Humidity calibration system
The
Theory and Operation of Optical Chilled Mirror Hygrometers for Humidity
Calibration
Condensation
Hygrometers as Humidity Transfer Standards
A
comparison of chilled mirror hygrometers
Development
of a Bench-Top Time Proportional Humidity Generator with Chilled Mirror
Hygrometer Reference Standard
The
State of Pressure Uncertainty by Ken Kolb
Differential
Pressure Primary Standard - Technical Aspects
Dew
Point Measurement in Metal Heat Treatment
The
Effect of Air Laden Soluble Salts on Dew Point Measurement Using Condensation
Hygrometers
Humidity Analysers - Theory and information of Condensation Chilled Mirror Hygrometers - from Able Instruments and Controls.
The following papers are from gesensing
"Achieving
Reliable Parts-Per-Billion Calibration of Moisture Analyzers"
Care
of Grain: Guide to Professional Grainstore Management
Dampness
Measurement in Concrete Floors
Ventilation,
damp, mould & condensation feature article from "Housing Association
Building and Maintenance"
8.10
Online
Moisture Analysis in Materials Handling - Graeme McGown - Moisture analysis
during materials handling and processing presents a number of challenges that
can be solved with appropriate use of online techniques - from Intalysis and www.processonline.com.au
Hydrocarbon Dew Point Technology- The condensation temperature of heavy hydrocarbon components in gas - commonly known as the hydrocarbon dew point - is a complex and difficult parameter to measure. Traditionally this measurement has been made using a manual optical technique based on the cooling of a mirrored surface in contact with the hydrocarbon gas mixture. Whilst it is possible, with experience and application, to obtain repeatable results with a manual dew-point hygrometer, the subjective nature of this technique yields it ever less applicable in today's de-regulated gas markets where continuous and precise measurement of this critical parameter are demanded - - from Michell Instruments.
The following papers are from gesensing
Moisture
Measurement in Natural Gas - Priya Rajesh - This article focuses on
the basics of natural gas, why moisture measurement in natural gas is important
and the various types of moisture measurement instruments.
The
War against Water - Ken Soleyn -Water even in small concentrations, poses
large problems for the distribution of natural gas. Natural gas is dehydrated
and treated prior to transportation and use, at considerable cost to the
supplier and consumer. However attempts to reduce dehydration results in a
reduction of 'gas quality' and an increase in maintenance costs and
transportation, as well as potential safety issues. Consequently, to strike the
right balance it is important that the water component of natural gas is
measured precisely and reliably. A new instrument that utilises a tuneable diode
laser is now available to continuously monitor the water concentration in
natural gas and offers considerable advantages over traditional instrument
technology.
The Following technical articles are from Michell Instruments
Moisture
Measurement in Natural Gas -Thanks
to Rolf Kolass, Michell Instruments GmbH,
Hydrocarbon
dew point of gas
- Redeveloping
Instrumentation to reduce the cost of ownership-Thanks
to Jon
Severn
Hydrocarbon
Dew-point – A Key Natural Gas Quality Parameter
Moisture
and Hydrocarbon Dew-point Measurement in Natural Gas
Development of a Bench-Top Time Proportional Humidity Generator with Chilled Mirror Hygrometer Reference Standard - from gesensing
Trace
Moisture Measurement in Inert, Reactive and Corrosive Ultra High Purity
Semiconductor Gases - from Able Instruments and
Controls.
Moisture
Behavior in Ultra-High Purity Gas Distribution Systems - The purpose of this
Application Note is to familiarise users of CQC systems with the difficulty of
making ultra-trace level moisture measurements, to set a practical expectation
for moisture analyzer performance and to establish guidelines for the proper use
of these analysers in controlling and monitoring moisture in UHP gases - From
Delta F.
Detecting
Single-Digit parts per billion Levels of Moisture
in Ammonia Gas - Andrew O. Wright,
Clayton D. Wood, Kimberly J. Reynolds and Mark L. Malczewski - An
increasingly important chemical used in the manufacture of
electronic devices such as high-intensity light-emitting
diodes (LEDs) is ultrahigh-purity (UHP) anhydrous ammonia. However,
the presence of residual trace moisture iUHP ammonia is a
matter of concern. Especially in blue and white
LEDs, there is a strong correlation between device
performance and moisture content in the process ammonia
used during manufacturing. In addition, increasing
chemical consumption is forcing many facilities to use
bulk storage tanks as a single supply source instead of
cylinders as supply sources for individual tools.
In light of these trends, it is imperative to have a
robust, continuous process instrument with a single-digit
parts-per-billion detection limit that can measure moisture in
ammonia.
Relative
Humidity Tables- from the National Weather Forecast
Centre
Humidity
Calculator - from the Australian Government Bureau of
Meteorology
Humidity Charts
from the Old Farmers Almanac
Dew
Point Temperature Table (Fahrenheit) - Also includes
equations for calculating dew point temperature. From the University of
Nebraska-Lincoln
7.11Humidity
Calculator for Conversion of Humidity Measurements - The humidity
calculator from E+E Elektronik is used for the rapid conversion of humidity
measurements. Uniquely, the humidity calculator also includes measurement
uncertainties in the calculation. This is helpful for obtaining realistic
and reliable overall uncertainties based on the specification of the
measuring device.
Humidity Analysers - Product quality improvement with correct moisture measurement in thermal processes using electrolytic hygrometers - from Able Instruments and Controls.