1. In order to ensure that the elastic element of the precision 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 consider the speed of the measured pressure change. There is enough leeway.
When using a pressure gauge to measure stable pressure, the maximum working pressure should not exceed 2/3 of the range; when using a pressure gauge to measure pulsating pressure, the maximum working pressure should not exceed 1/2 of the range.
2. When using a precision pressure gauge to measure high pressure, the maximum working pressure should not exceed 3/5 of the range. In order to ensure the measurement accuracy, the minimum working pressure should not be lower than 1/3 of the range. According to this principle, after calculating a value according to the measured maximum pressure, select a measurement range slightly larger than this value from the product catalog of the pressure gauge.
3. The precision pressure gauge should be selected according to the working pressure of the boiler, and the limit value of the range scale should be 1.5 to 3.0 times the working pressure, preferably 2 times.
In industrial boilers, the actual situation is that the actual operating pressure of the boiler is always lower than the rated pressure on the nameplate, both industrial steam boilers and hot water heating boilers. For example, for a 4t/h steam boiler, the rated pressure is 1MPa. If the manufacturer is equipped with a pressure gauge according to 1.5 times, it should be equipped with a 1.6MPa range pressure gauge.
If the user is required by the production process, the actual operation can meet the process requirements under the pressure of 0.5MPa. At this time, when the range is run, the pointer of the pressure gauge points to a position less than one-third of the range, and the angle that the pointer rotates is very small. , that is, the range of the pressure gauge selected is too large. The same is true for hot water boilers. For example, the rated pressure of the heating boiler is 0.7MPa, and the pressure gauge should be 1MPa or 1.6MPa. If the pressure gauge is equipped with 1MPa, it is afraid that the pressure gauge will be overloaded during the hydraulic test, so it is equipped with a range of 1.6 MPa. MPa pressure gauge.
In actual operation, as long as 0.2MPa can meet the heating requirements, and the pointer of the pressure gauge points to one-eighth of the range, it is difficult to make people believe in the accuracy and sensitivity of the pressure gauge.
4. In order to solve the above problems, two kinds of pressure gauges should be used, that is, in the hydraulic test, the pressure gauge equipped by the boiler factory according to the rated pressure should be used.
5. Equip a pressure gauge according to 2 times the actual working pressure during daily operation. If the working pressure is 0.2MPa, a pressure gauge with a range of 0.4MPa should be used. In this way, the pointer is in the middle of the dial, vertically upward. The seat 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 overpressure indication.