AS 1141.2:2015 pdf download.Methods for sampling and testing aggregates Method 2: Basic testing equipment.
3 EQUIPMENT
3.1 General
Standard items of laboratory equipment in everyday use, such as test tubes, Petri dishes, beakers, mechanical stirrers, mortar and pestles, stirring rods, mixing apparatus, dishes and trays, spatulas, and similar items are not described in this Standard. Similarly, tools such a shovels or trowels, ancillary equipment such as barrows or trolleys, and miscellaneous items such as brooms, bags and brushes are not described. These and similar aids, need to be of good commercial quality to ensure successful sampling and testing.
3.2 Equipment calibration
Prior to commissioning any item of test equipment, it shall be established that the equipment is capable of meeting any performance requirements or other conformance criteria, such as dimensional tolerances, which are listed within this series of Standards for the applicable equipment category. This will normally entail formal calibration by a recognized calibration authority, or an equivalent process, to ensure that equipment compliance is established in a way that is traceable to Australian, or international, measurement standards, where available.
A program for ongoing assurance of equipment capability shall be established for each equipment item to ensure that the performance is not compromised in any way due to wear or deterioration resulting from usage, aging or possible mishandling of the equipment. This will require the operators of such equipment to define the intervals for equipment recalibration. In establishing the recalibration intervals, the equipment operator may take into account any schedule of equipment checks designed to identify drift or other loss of performance capability (i.e. between successive recalibrations) that would then trigger an unscheduled recalibration.
Establishing an effective equipment assurance program will involve consideration of how effectively the measurement uncertainty is being controlled for individual equipment items. In the absence of such supporting analysis, suggested intervals for laboratory test equipment checks and calibrations are available from the publications of some laboratory accreditation bodies.
NOTE: In Australia, the responsible authority for laboratory accreditation is the National Association of Testing Authorities (NATA).
4 MAINTENANCE
All items used in sampling and testing shall be maintained so that they comply with the specified requirements.
Before use, equipment shall be examined for signs of’ excessive wear or damage. No equipment that appears to have been excessively worn or damaged shall he used for testing until it has been checked and, if necessary, repaired.
5 BASIC EQUIPMENT REQUIRED
5.1 Balances
Balances shall comply with the limit of performance specified in the individual test methods (see Note 1).
NOTES:
1 For a balance, the limit of performance (±F) means that there is not more than five chances in one hundred that the measured mass will be outside (±F) of the true value.
2 The limit of performance is applied where no calibration corrections are used in the normal operations of weighing on the balance.
Accredited balance calibrators are usually required to test and report on balances in accordance with NMI Monograph 4.
5.2 Drying ovens
Drying ovens shall comply with the following:
(a) A temperature-sensing device shall be mounted in the oven so that it accurately indicates the temperature of the oven enclosure. The temperature indicator shall be located so that it can be observed from the working space in front of the cabinet, and shall be readable to 0.5°C. Additional sensors may be included in the oven design, in which case the temperature indicator may also show an average oven temperature.
(b) The oven shall be fitted with an adjustable, automatic control device for maintaining the oven temperature within the range of土2°C of the indicated oven temperature when empty and with the vents open and with the oven operating at the temperature settings used in the laboratory.
(c) Forced air ventilation shall be provided to assist escape of moisture-laden air. NOTE: For older ovens where forced air ventilation is not provided, records should be maintained which demonstrate the capability of the oven to achieve a minimum average evaporation rate of 15 g/h and not less than 10 g/h from each measured location in the oven, when measured by the procedures given in AS 1141.24.
(d) The maximum temperature at any point shall not exceed the indicated temperature by more than 士5°C and shall be determined by placing temperature measuring devices, readable to 0.5°C， at the centre and eight corners of the oven. The temperature measuring devices shall not be placed within 50 mm of the walls, floor or ceiling of the oven. Readings shall be determined after a minimum of 12 h of continuous operation with the oven empty, the vents open, any forced ventilation system in operation and the door closed.AS 1141.2 pdf download.