ISO 139 pdf download – Textiles – Standard atmospheres for conditioning and testing.
3 Requirements
3.1 Standard atmosphere
Standara atmospheres shall nave a temperature ot 20.0 C ano a relative numiarry 0* 65,0’s.
3.2 Standard alternative atmosphere
Standard alternative atmospheres shall have a temperature of 23.0 °C and a relative humidity of 50,0%.
The alternative atmosphere may be used only if the parties involved agree on its use.
3.3 Tolerance zone for the standard atmosphere and for the standard alternative atmosphere
The tolerance for temperature is ± 2,0 °C.
The tolerance for relative humidity Is & 4.0 %.
NOTE For control ol standard atmospheres, see Annex A.
4 Apparatus
4.1 MeasurIng devices for temperature and relatIve humidIty
Measuring devices shoukl meet The following requirements:
— resolution: for temperature. 0,1 °C or better, and for relative humidity, 0,1 % or better;
— uncertainly of measurement: tor temperature, ± 0.5 “C or better, and tar relative humidity. ± 2,0% or better
Calflation to determine the uncertainties ot the measurement sensors shall be carried out regularly.
4.2 LimItations to measurement devices
Devices used for the measurement 01 relative humidity and temperature in the conditioned atmosphere shall be separate from those normally used tor controlling heating, ventilation and air condition Wtg ducts.
5 Procedures
5.1 Reading frequency for continuous monitoring
Sensor readings of a conditioned atmospheric enclosure shall be made at such a frequency that any short-term out-of-tolerance-limit events can be detected (see Annex A for additional information).
5.2 Spatial variation
Mere than one measuring devices might be required to ensure adequate monitoring ot the atmospheric conditions throughout the enclosure (see Annex A).
An air-conditioned laboratory shall provide and maintain a standard atmosphere as defined in 3.1 or 3.2, within the tolerance zone as defined in 3.3.
The specified condition of temperature and relative humidity shall be considered to have been attained when the followin9 requirements are satisfied.
a) The mean terrerature and relative humioity over any continuous 1 h period shall conform to the tolerance zone at the standard atmosphere conditions
b) The spatial variation of the standard atmosphere shall comply with the specified tolerance zone.
A.2 Apparatus
Apparatus shal be in accordance with the requirements 01 4.t A device such as a digital or electronic sensor with a recorder output for continuous monitoring is suitable.
A.3 Procedure
A3.1 Spatial variation
Monitor periodically the spatial variation ol the atmospheric conditions within the laboratory at various positions. The number of position checks required shall be equivalent to a minimum of 1 per 50 m3.
Where the spatial variation does not comply with the tolerances, the air movement within the laboratory shall be checked.
A.3.2 Positioning of the continuous monitoring devices
Variations in temperalure and relative humidity are likely to exist throughout the working space. The selection of an appropriate monitoring position can be made only after position checks have been conducted. The selected position should be close to the main working area
In order to better define “tolerance zone”, as defined in 2.4 and specified in 3.3 (for both temperature andrelative humidity), the concepts of specification zone and conformity zone should be introduced (these notionshave been developed in IS0 14253-1).This International Standard proposes rules to determine whether or nota characteristic conforms to the specification, taking into account the uncertainty of measurement.
The specification zone represents what the laboratory can practically control and the conformity zonerepresents the theoretical values that the laboratory wishes to reach.
EXAMPLE For the relative humidity, based on a conformity zone ol土2 % and an uncertainty of measurement ol 土2%,the specification zone is estimated as王4%.
The relationship between ‘specification zone” and “conformity zone” is shown schematically in Figure B.1.
ISO 139 pdf download – Textiles – Standard atmospheres for conditioning and testing
