national measurement act 1960

determination by the national standards commission

Recognized-Value Standard of Measurement

of Viscosity

In pursuance of paragraph 8A(1)(a) of the National Measurement Act 1960, the National Standards Commission hereby determines that the magnitude of the dynamic viscosity of water prepared as in the Schedule and at a temperature in the range 19.98°C to 20.02°C shall be a recognised-value standard of measurement having the value of 0.001 002 Pa.s.

For the purposes of this Determination the chance is not more than one in one hundred that the viscosity of the water differs from the designated value by more than 0.000 001 Pa.s.

The Schedule

The water shall have been prepared by being distilled at least twice, the final distillation having been performed after addition to the water of potassium permanganate to a concentration of not less than one part in ten thousand by mass. In the final distillation the distillate shall have been collected in silica or borosilicate glass. The water shall have been maintained subsequently in contact with air at a pressure in the range 80 000 to 120 000 Pa, and shall be free from bubbles. The electrical resistivity of the water at 20°C shall be not less than 1 000 Ω.m.

Dated this 21st day of March 1985

The common seal of the national     T.J. PETRY

standards commission was hereto

affixed by authority of the Commission

in the presence of