Metrology is the science of measurement.

Metrology is important in international trade because it provide the necessary technical means to ensure correct measurement.

The performance of test and measuring equipment may change with time, due to the influence of the environment to which it is exposed, wear and tear, overload or because of the improper use. Calibration intervals are usually recommended by the manufacturer of the measuring or test equipment. It may also depend on the performance and frequency of use of the equipment.

Choose any calibration laboratory whose calibration is traceable to national standards. However, for internationally whose calibration certificate, you have to chose a calibration laboratory that has been accredited by an accreditation body that has signed a mutual recognition arrangement (MRA) established by one of the regional accreditation cooperation (ILAC).

No, you need only calibrate or verify measuring equipment that you use to ensure compliance with specified requirement.

To measure is to compare an unknown value of a quantity with the standards unit of the same quantity and to express the result as a fraction or multiple of the unit in question. This comparison, done with the help of a measuring instrument is never perfect. The instrument is accurate to a degree and the accuracy itself is certain only within limits that are expressed quantitatively as the uncertainty. The estimation of the uncertainty of a measurement enables those who use measurement result to assess the reliability of those results. The accuracy of a measuring instrument is it ability o give a measure close to a “true” value of represented by a standards.

Traceability implies that a measurement can be related to national or international measurement standards, and that this relationship is documented. Traceability is defined in VIM as the property of the result of a measurement or the value of standards whereby it can be related to stated references, usually national or international standards, through an unbroken chain of comparisons all having stated uncertainties.

A measurement standards can be a physical measure, measuring instrument, reference material or measuring system intended to define, realize, conserve or reproduce a unit or one or more values of a quantity to serve as a reference. The hierarchy of measurement standards starts from the international standard at the apex and goes at the way down to working standards.

Calibration: is the set of operations that establish, under specified conditions, the relationship between values of quantities indicated by a measuring instrument or measuring system, or values represented by a material measure or a reference material, and the corresponding values realized by standards.

Verification is the procedure which includes the examination and marking and/or issuing of a verification certificate, that ascertains and confirms that the measuring instrument complies with the statutory requirements.Adjustment is the operation of bringing a measuring instrument into a state of performance suitable for its use.

Gauging is the operation of fixing the positions to the seale marks of a measuring instrument, in relation to the corresponding values of the measurand. A typical application of gauging is the determination of the content of a storage tank for liquids by relating volume marks on a dip stick to the liquid level in the tank.