The kilogram is the unit of mass, which is one of the seven basic units of the International System of Units (IS). It is equal to the mass of the international prototype kilogram. The international prototype kilogram is a cylinder of platinum-iridium alloy kept at the International Bureau of Weights and Measures (BIPM) in France. Copies of this prototype have been distributed to the member countries of the meter convention. These copies are considered as reference standards for the dissemination of the unit of mass at the national level. It is worth mentioning that the unit of mass is currently the only unit still based on an artifact. Research in this area is now focused on the redefinition of the kilogram in terms of the constants of physics, which by their nature are invariant and universally accessible. Three sets of weights of OIML E1 class, that cover the range from 1 mg to 20 kg, are maintained by NSCL as the reference measurement standard of mass for Syria and for the dissemination of the unit of mass. NSCL provides the following calibration services, the details of which are shown in the table below:

• Calibration of standard weights of OIML classes E2, F1, F2, M1, M2, and M3, or any other equivalent recognized classes. Calibration weights of OIML classes E2 & F1 follows measuring their magnetic properties, using susceptometer YSZ01C.
• Calibration of Electronic weighing instruments (Classes I and II according to OIML R76-1). This service is carried out at the instruments place of use.

How To Request Calibration Services