scope:

Scope and field of application

This part of ISO 649 specifies requirements for five basic series of glass hydrometers of constant mass which are graduated to indicate density (kg/m³ or g/ml) at 20 ^OC.

Each series comprises hydrometers which between them cover the interval 600 to 2 000 kg/ma³ or 0,6 to 2,0 g/ml. The hydrometers are graduated appropriately for use in liquids of low, medium or high surface tension.

It also specifies three sub-series of hydrometers which are graduated to indicate density at either 20 ^OC or 15 ^OC. These hydrometers have smaller tolerances on scale error, are limited to the range 600 to 1 100 kg/ma³ or 0,6 to 1,l g/ml and are for use in liquids of low surface tension.

This International Standard does not cover hydrometers with a built-in thermometer, for which a separate International Standard is under consideration. The hydrometers comply with the requirements of ISO 367.

A table of standard categories of surface tension is given in annex A. A table of recommended stem diameters is given, for guidance in manufacture, in annex B.

Part 2 of this International Standard deals with test methods and use of density hydrometers.