AATCC 76 pdf free download

AATCC 76 pdf free download.Electrical Surface Resistivity of Fabrics.
4.3 The radioactive bar emits alpha radiation which is externally harmless to the human body. The radioactive isotope polonium 210 is toxic and precaution should be exercised to prevent ingestion or inhalation of the solid material. Do not take the radioactive bar apart or touch the radioactive strip under the grid. If the strip is touched or handled, wash hands thoroughly at once. Return the device to the manufacturer when it loses its elTectiveness as a static eliminator or for disposal if use is to be discontinued. Do not discard as scrap.
5. Apparatus and Materials
5.1 Electrical resistance meter (see
I I . I).
5.2 Conditioning and test chamber (see
11.2).
5.3 Standard resistors (see 11.3).
5.4 Radioactive bar (see 11.4).
5.5 Two rectangular flat metal surfaces of suitable size to serve as electrodes.
5.5.1 As an alternative, two concentric ring electrodes of spacing suitable to the material being measured and the purpose ofthe results (see 11.1.1).
6. Test Specimens
6.1 Adjust the size of fabric test specimens to suit the electrodes of the particular equipment being used. When using parallel plate electrodes, the width of the specimen must not exceed the width of the electrodes. When using the concentric rings, any size specimen at least as large as the outer ring may be used. Avoid contaminating the area on which the measurement is to be made.
6.2 Specimens for use with instruments providing parallel p/aft’ electrodes. Prepare 2 sets of 3 test specimens each. 1 set each so that the direction of testing is parallel to the yarns in the length direction of the fabric and I set with the direction of testing parallel to the width direction of the fabric.
6.2. 1 Test specimens fOr use with in— siruinents providing concentric ring dcc— (rocies. Prepare I set (3 test specimens) since, with this type instrument, the resistance is measured in both fabric length and fabric width directions simultaneously.
6.2.2 Depending on the fabric construction or end-use, it may be advisable to differentiate between face and back measurements. Each test specimen should be taken from a different part of the fabric.
7. Procedure
7.1 Calibrate the electrical resistance meter according to the manufacturer’s recommendations. This calibration should be repeated periodically (see 10.3).
7.2 Condition the test specimens in a suitable testing chamber or conditioning room at a predetermined relative humidity that will reflect the conditions at which information on the electrical resistivity of the fabric is needed.
7.2.1 For most fabrics which require antistatic treatments or whose static propcnsity is critical, measurements at 2O% relative humidity will be most meaningful.
7.2.2 In less critical situations 40% relative humidity may be employed.
7.2.3 For special requirements other relative humidities may be used. For example, preconditioning at 50% ± 2% RH at 21 ± 2°C is required for antistatic sheeting. film and textiles for use in hospital operating rooms (see 11.2.1). Measurements may be made under other conditions or ranges of conditions that are applicable to the end use (such as 65% RH and 24°C). It is preferable to keep the temperature or humidity consistent for all measurements.AATCC 76  pdf download.