Standard laboratory atmosphere

Standard Laboratory Atmosphere. Standard laboratory atmosphere is defined as an atmosphere having a temperature of 23 C (73.4°F) and a relative humid-... 

Conditioning procedures of test specimens and products are important in order to obtain reliable, comparable, and repeatable data within the same or different testing laboratories. Procedures are described in various specifications or standards such as having a standard laboratory atmosphere [50 2% relative humidity, 73.4 1.8°F (23 1°C)] with adequate air circulation around all specimens. The reason for this type or other conditioning is due to the fact the temperature and moisture content of plastics can affect different properties. 

Standard on Fire Protection for Laboratories Using Chemicals Recommended Practice on Materials, Equipment and Systems Used in Oxygen-Enriched Atmospheres Standard for the Storage, Use, and Handling of Compressed Gases and Cryogenic Fluids in Portable and Stationary Containers, Cylinders, and Tanks Liquefied Petroleum Gas Code... 

The value of 23 °C was chosen so that the certificate values would be correct for the standard laboratory atmosphere (10). 

In addition to testing methods and product specifications, ASTM Committee D-20 on Plastics has also prepared definitions of terms and recommended practices for molding test specimens and constructing testing equipment, conditioning and weathering procedures, and related standards. These are published in the ASTM books of standards (4-7). There is also a federal standard for laboratory atmospheric conditions for testing (34). 

U. S. Federal Supply Service, Standard for Laboratory Atmospheric Conditions for Testing, ... 

Use of the SPB-1 column system A qualitative standard mixture is first analyzed (see Figure 1). A reagent blank analysis is then performed to monitor interference from the laboratory atmosphere. A sealed headspace vial containing internal standard solution (1,1,2-trichloroethane - - ethylbenzene in analyte-free diluted whole blood) is incubated (65°C, 15 min) and a portion (100-300 pi) of the headspace is taken for analysis using a warmed (40°C) gas-tight glass syringe. Subsequently, the sample (whole blood, plasma, serum, or urine) (200 pi) is added to the same vial and, after reincubation (65°C, 15 min), a further portion of headspace is taken for analysis. 

Strength, dry—The strength of an adhesive joint determined immediately after drying under specified conditions, or after a period of conditioiung in the standard laboratory atmosphere. 

Standard condition n. Standard condition is that reached by a specimen when it is in moisture equilibrium with a standard atmosphere. Standard condition is seldom realized in practice since laboratory atmospheres are continually fluctuating between narrow limits, and it is not practical to wait for the attainment of moisture equilibrium, which would require several days or more for tightly wound samples of high regain material. Practically, specimens are brought to moisture equilibrium in the standard atmosphere for testing as defined in these definitions. The term standard condition should not be used as a Syn the concept of standard atmosphere . 

The specimens are conditioned using standard conditioning procedures. Since the tensile properties of some plastics change rapidly with small changes in temperature, it is recommended that tests be conducted in the standard laboratory atmosphere of 23 2°C and 50 5 percent relative humidity. The Procedure A of ASTM methods D 618 (as explained in Chapter 11) is recommended for this test. 

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