Reading of U-type differential pressure gauge
Check the division value on the U-shaped differential pressure gauge, which is the reading of each small grid, and the final read data must be accurate to the next digit of the division value;
Read and record the data on the left and right respectively; calculate the difference between the readings on the left and right, and this is the final result.
Since the inner diameters of the glass tubes on both sides of the U-tube manometer are difficult to keep completely consistent, in order to limit the introduction of additional errors when reading the value, the U-tube manometer should be placed vertically;
And read the liquid level height of the two tubes at the same time, the field of vision should be flush with the liquid level, and the reading should be based on the tangent line at the top of the meniscus of the liquid level.
The normal reading error is about 1mm, and if it is a secondary reading, it is about 2mm.
The measurement accuracy of the U-shaped tube pressure gauge is determined by the measurement range, the size of the measured pressure and the selection of the working fluid.
After the working fluid of the U-tube manometer is determined, the larger the measurement range, the higher the measured pressure, and the higher the measurement accuracy.
For example, when water is used as the working fluid, the accuracy is ±0.5% at 5kPa, ±1% at 2.5kPa, ±2.5% at 1kPa, and ±5% at 0.5kPa.
In addition, if you want to improve the measurement accuracy and flexibility when the height is constant, you should choose a working fluid with low density.
In the process of use, it should also be noted that the liquid level of the glass tubes on both sides must be read at the same time. It is not allowed to read only the value of one glass tube and multiply it by two. This must be paid special attention to.
The importance of reading the values of both glass tubes at the same time can be understood from the following example.
