"ZERO" Zone

Among the several minimum requirements established in INMETRO’s Ordinance there is the size of the tolerance range around the zero point, which is also known as zero zone, which is located at the beginning of the manometer scale. The Ordinance orders that the tolerance range shall not be greater than the one corresponding to +/ - 3mmHg in the scale. For a better view, this means that the total area of the tolerance range can not cover an area larger than the one equal to the area of three traces in the scale. It is quite simple to see it visually. Most of the portable sphygmomanometer has the same size, and taking our Premium-make device as a reference, the zero zone shall not measure more than 3 mm long with a rule.

The main consequence of a tolerance range greater than what is allowed is the hide of device’s non-gauging, as the pointer shall still be within the tolerance range, even when it is not gauged.