Anhui Star Control Instrument Co., Ltd.

Anhui Star Control Instrument Co., Ltd.

Pressure gauge range selection

1. In order to ensure that the elastic elements of the pressure gauge can work reliably within the safe range of elastic deformation, the selection of the pressure gauge range should not only be based on the size of the measured pressure, but also the speed of the measured pressure change, and its range needs to be retained. Enough room. When using a pressure gauge to measure the steady pressure, the maximum working pressure should not exceed 2/3 of the measuring range;
2, using a pressure gauge to measure pulsating pressure, the maximum working pressure should not exceed 1/2 of the range;
3. When using a pressure gauge to measure high pressure, the maximum working pressure should not exceed 3/5 of the measuring range. In order to ensure the measurement accuracy, the minimum working pressure should not be less than 1/3 of the measuring range. According to this principle, after calculating a value based on the measured maximum pressure, select a measurement range slightly larger than the value from the pressure gauge product catalog.
4, should be based on the working pressure of the boiler to choose, the scale of the scale limit should be 1.5 to 3.0 times the working pressure, preferably 2 times. In industrial boilers, the actual situation is that the actual working pressure of the boiler is always lower than the rated pressure on the nameplate. This is true for industrial steam boilers and hot water heating boilers. For example, for a steam boiler of 4t/h, the rated pressure is 1 MPa. If the manufacturer is equipped with a pressure gauge at 1.5 times, it should be equipped with a 1.6MPa range pressure gauge. If the user needs the production process, the actual operation can meet the process requirements under the pressure of 0.5MPa. At this time, the operating range and the pointer of the pressure gauge will be less than one-third of the range. The pointer turns the angle very small. That is, the pressure gauge selected is too large.
The same is true for hot water boilers. For example, the rated pressure of a heating boiler is 0.7 MPa, and the pressure gauge is equipped with a pressure gauge of 1 MPa or 1.6 MPa. If a pressure gauge equipped with 1 MPa is used, it is feared that the pressure gauge will be overloaded during the hydrostatic pressure test. Therefore, the measuring range is 1.6MPa pressure gauge. In actual operation, as long as 0.2 MPa can meet the heating requirements, the pointer of the pressure gauge is one eighth of the range, which makes it difficult to believe the accuracy and sensitivity of the pressure gauge.
5. In order to solve the above problems, two pressure gauges shall be used, that is, when the water pressure test is conducted, a pressure gauge equipped with the boiler plant according to the rated pressure shall be used;
6, in the daily operation according to the actual working pressure of 2 times equipped with a pressure gauge. If the working pressure is 0.2MPa, a pressure gauge with a 0.4MPa range is used. This position the pointer in the middle of the dial, vertical upwards. The starting pressure of the safety valve is also adjusted according to the working pressure, and the pressure gauge still has enough margin to cope with the over pressure indication.
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