The method of judging the accuracy grade of pressure gauge.
The accuracy grade of the pressure gauge is expressed as a percentage of the allowable error in the measuring range of the pressure gauge, which is generally divided into seven grades: 0.5, 1, 1.6, 2, 2.5, 3, 4 (grade 3 and 4 are not used on the boiler). The smaller the value, the higher the accuracy.
For example, for a pressure gauge with a dial range of 0 to 2.5 MPa precision, the allowable error between the pressure value indicated by its hands and the actual pressure value of the tested medium shall not exceed the upper 2.5MPa × 2.5% = ±0.0625 MPa;. When the pressure indicated by the pressure gauge is 0.8MPa, the actual air pressure is between 0.7375~0.8625MPa.
1. Precision pressure gauge grade selection:
According to the national regulations: the grade accuracy of the standard pressure gauge can not be greater than 1/3 of the grade accuracy of the pressure gauge being tested.
If the grade of the pressure gauge that needs to be verified is 1.6, then the grade accuracy of the standard pressure gauge should be less than the precision pressure gauge of grade 0.5, and the national precision of the precision pressure gauge has been clearly stipulated, so the 0.4 grade precision pressure gauge can be selected.
2.Selection of measuring range of precision pressure gauge:
Precision pressure gauges are more sophisticated instruments. When in use, try not to exceed 2/3 of the measuring range of precision pressure gauges.
If the pressure gauge that needs to be verified is class 1.6and the range is 10kg, and the pressure unit is converted to MPa, then the range of the selected precision pressure gauge is 1 divided by 2/3, which is equal to 1.5MPa, while the national precision pressure gauge does not have the precision pressure gauge of 1.5Mpa in the standard range, then choose the precision pressure gauge of the near range, that is, 0-1.6MPa.
