AS 2193-2005 pdf download.Calibration and classification of force-measuring systems.
3.2.3 Calibration b elastic working force standards
Where a tbrce scale is to be calibrated at a given lince by an elastic orking force standard. the maclime or force-measuring system shall he operated to apply the force to the instrument so that the reaction is along the straining axis of the machine or force-measuring system. Multiple working force standards may be used in parallel, thereby providing a convenient means of measuring greater ranges of force. When used in this mode, the working force standards shall be arranged so that the resultant reaction is along the straining axis of the machine or force-measuring system.
Unless otherwise specified, the application of each force shall he controlled to ensure that stability is achieved.
If the force scale is to be calibrated for decreasing force. the working force standard shall have been calibrated under conditions of decreasing force, unless it has been established that the effects of hysteresis in the working force standard are insignificant in relation to the required accuracy of the testing machine or force-measuring system.
Working force standards may have been classified either for use at any force within a given range. or for use only at selected forces. Instruments that have been allocated a Continuous Class, in addition to Point Class, may be used to measure any forces in that part of the range which has the required Class. However, instruments that have been allocated a Point Classification shall only be used to measure the nominal values of force at which they were calibrated.
It is necessary to allow the calibrating instrument to reach a stable temperature before the calibration is commenced. Where the instrument is not temperature compensated, the effects of temperature shall be taken into consideration (see Clause 3.9).
In order to stabiliie the iero reading of the instrument, it is necessary. immediately before use, to apply a force to the instrument in the direction in which h is to be used, equal to the maximum force to be measured, and to repeat the procedure as necessary to produce a stable cro reading.
3.3 FOR(’F. CALIIIRATION PRo(’n)LkF:
3.3.1 General
Where practicable. the procedure for calibration shall be similar to the conditions of normal operation. e.g. where the straining mechanism is not used to apply the forces, as occurs when weights are used, the straining mechanism shall, where practicable. be operated to provide similar conditions to those present during testing.
NOTE: See Appendix H.
3.3.3 Preliminary Inspection
Before applying the procedure described in Clauses 3.3.4 to 3.3.6. it shall be ascertaiiied that—
(a) the testing machine or force-measuring System is in good working order and condition:
(b) the control of application of the forces is adequate for the method of calibration to be used:
(c) tension holders or compression platens to be used with the working force standard are satisfactorily aligned and function correctly:
(d) the maximum reading device, e.g. a friction pointer or pawls and ratchet, functions satisfactorily over the range of the scale to be calibrated (where applicable) and
(e) the recorder paper is suitable for the machine (where applicable).
NOTES:
I Other aspects of machine function such as reliable operation of soft are. ongoing calibration stability, etc.. as well as possible safety concerns should be considered before proceeding with calibration.
2 The decision to proceed with the calibration will depend on the result of the preliminary inspection and on agreement between the customer and the calibrating authority.
3.3.4 Setting up
The indicator of the testing machine or force-measuring system shall be set to zero before the first series of readings is commenced. If the design of the machine or force-measuring system is such that the gravity force exerted by the weight carrier or working force standard is applied to the force-measuring system. the zero shall be set with the working force standard set up in the machine. If the provision for zero adjustment of the machine or force- measuring system is inadequate for this, the weight carrier or working force standard shall be considered as a seight and due allowance made for the gravity force it applies. If a maximum reading device is to be used during the calibration, the zero setting shall be made with the device disengaged.
It is essential that the working force standard set up in the machine ensures that the forces are applied along the straining axis, as specified in Clause 3.2.
Where a working force standard is used, sufficient lime shall he allowed for the instrument to attain a stable temperature. The temperature of the instrument shall be recorded at appropriate intervals (usually at the end of each series of calibration forces).AS 2193-2005 pdf download.Calibration and classification of force-measuring systems
Calibration and classification of force-measuring systems
