Resources

SmartLog | Papers | Applications | Humidity Calculator | Definitions

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SmartLog

Download PGC's free Windows-based controller-interface software. Log, monitor, and control chamber conditions from your PC.

SmartLog.zip

Papers

Issues to Consider when Complying with ICH Guidelines Involving Temperature and Relative Humidity Conditions

TAPPI Rooms - Criteria for Obtaining Specified Humidity and Temperature Conditions

Conditioning – Is it Really Necessary? (Only When Your Testing is Important)

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Applications

Where the equipment presently sells:

Pharmaceuticals

Main Applications

• Product Stability Testing (shelf life)
• Packaging (23°C/50%)

Stability Specifications (ICH)

• 25°C/60%
• 30°C/60%
• 40°C/75%
• 40°C/15%
• 5°C

Generally ±2°C and ±5% RH

PGC Product Utilized

• Reach-ins
• Walk-ins
• Conditioners for existing rooms

References

• Johnson & Johnson
• Abbott
• PPD
• McNeil
• Cordis
• Quintiles
• Andrx

Packaging/Pulp and Paper

Main Applications

• TAPPI Labs--Technical
• Association of Pulp and Paper Industry
• Package testing

Common Conditions

• 23°C/50% (Main TAPPI Spec.)
• 35°C/30% (TAPPI pre-conditioning)
• 32°C/90%
• 5°C/85%

TAPPI Tolerance is ±0.5°C and ±2% RH

PGC Product Utilized

• Walk-ins
• Conditioners for larger TAPPI Labs

References

• International Paper
• Georgia Pacific
• Mead-Westvaco
• Inland
• Box USA,
• PCA
• Jefferson Smurfit

Electronics

Main Application

• Circuit Testing

Common Conditions

• 85°C/85%
• 85°C/60% (TAPPI pre-conditioning)
• 60°C/60%

PGC Products Utilized

• Reach-ins

References

• IBM
• Texas Instruments
• AT&T

Semiconductor (Process)

Main Application

• Mini-Environments (Microlithography)

Common Conditions

• 18-23°C/35-50% Extrememly tight tolerances (±0.05°C/±0.5%RH)

PGC Products Utilized

• Conditioners (Generally Custom)

Textile

Main Application

• Color consistency (Fabric and Carpet)
• Fabric testing

Common Conditions

• 22°C/65%
• Occasional High RH

PGC Products Utilized

• Reach-ins
• Conditioners

References

• Springs Industries
• Shaw
• Joan Fabrics

Tobacco

Main Application

• Smoking Machines
• Tobacco Sample Conditioning

Common Conditions

• 23.9°C/60% (±2%RH)

PGC Products Utilized

• Reach-ins
• Conditioners

References

• Philip Morris
• RJR
• Tobacco Institute Testing Labs
• Lorrilard
• Legget Group

Calibration

Main Application

• Humidity Sensor Calibrations

Common Conditions

• Various

PGC Products Utilized

• Reach-ins

References

• Kaye Instruments
• Intel
• Thailand National Standards Lab
• Chinese Government
• South Korean Navy
• Lockheed

Museums

Main Application

• Rare Document Storage

Common Conditions

• 10°C/50%RH

PGC Products Utilized

• Custom
• Rooms

References

• U.S. Library of Congress (Gutenberg and Mainz Bible Cases, Gettysburg Address, Top of Treasures Cases)

Wood Products

Main Application

• Strength and Stress Testing
• Laminate Adhesive Testing

Common Conditions

• Various

PGC Products Utilized

• Reach-ins
• Rooms

References

• Universities of Maine, North Carolina, Vancouver
• Hartco Flooring
• Thomasville

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Humidity Calculator

Download Edgetech's Humidity Calculator (EdgeCalc.zip)
This file is zipped. You can download a free version of Winzip here.

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Definitions

Dew Point (DP)

Dew point is that unique temperature to which the air (or any gas) must be cooled in order that it shall be saturated with respect to water.

Frost Point (FP)

Frost point is that unique temperature to which the air (or any gas) must be cooled in order that it shall be saturated with respect to ice.

The dew point or frost point DEFINES the partial pressure of the water vapor in the gas, from the Smithsonian Meteorological Tables.

Relative Humidity (RH)

Relative Humidity (RH) is the ratio of the actual vapor pressure in the mixture to the saturation vapor pressure, with respect to water, at the prevailing dry bulb temperature.

NOTE: RH is arbitrarily defined with respect to water even though it seems that it should be with respect to ice at -40&186;C (-40&186;F).

Dalton's Law (Pm)

John Dalton was the first to surmise that the total pressure (Pm) exerted by a mixture of gases or vapors is the sum of the pressures of each gas if it were to occupy the same volume individually. THe pressure which each gas component of a multiple constituent gas (such as air) exerts is called its partial pressure. If Px, Py, and Pz represent the respective partial pressure of gases X, Y, and Z in a mixture, Dalton's Law states:

Pm = Px + Py + Pz + ...

Elementary as it may seem, the concept of Dalton's Law is often overlooked when considering problems in humidity, because one forgets that the "water vapor" in a gas is actually a gas itself and must therefore be treated in accordance with the gas laws. Air must be considered a mixture of gases: oxygen, nitrogen, and water vapor (neglecting the minor constituents). All discussions of humidity can then be reduced to discussions of water vapor pressure, and all definitions encountered in humidity can be expressed in terms of vapor pressure.

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