Choose the quality of the pressure gauge
的弹簧管是具有一定横截面形状( 常用的有扁平圆和近似椭圆形两种) ，弯曲成“C” 形，而且能满足一定弹性要求的管状弹簧。 1. The spring tube of a general pressure gauge is a tubular spring that has a certain cross-sectional shape (commonly used are flat circles and approximately oval shapes), bent into a "C" shape, and can meet certain elastic requirements. If the spring tube is too small, it will affect the accuracy level of the pressure gauge. 2. The indication of the pressure gauge exceeds the allowable error, the indication adjustment screw of the gauge should be adjusted. If the gauge does not have the indication adjustment screw, the gauge can only be judged as unqualified. 3. The dial numbers and symbols of the pressure gauge dial shall be complete and clear. The dial indexing scales should be evenly distributed, and the center angle of the package is generally 270 °. The pointer of the pressure gauge should extend into all the indexing lines. The width of the pointer indicating end should not be greater than 1/5 of the minimum indexing interval. The distance between the pointer and the plane of the index plate should be within the range of 1 to 3mm. If the outer diameter of the case is above 200mm (including 200mm), the distance between the pointer and the plane of the index plate should be within the range of 2 to 4mm. 4. The case of the pressure gauge should be able to protect the internal parts from contamination. The pressure gauge should be equipped with a safety hole, and the safety hole must have a dustproof device. 5. For a pressure gauge with a stop pin, the pointer should be close to the stop pin when there is no pressure or vacuum, and the "shrinkage" must not exceed the specified allowable error. 6. Digital pressure gauge. It depends on the rationality of the overall structure, the selected material, the aging process of the electronic components, and the long-term stability.
量程怎么选择？ How to choose the pressure gauge range? 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 measured pressure, but also the speed of the pressure change. Enough room. When using a pressure gauge to measure stable pressure, the maximum working pressure should not exceed 2/3 of the range; 2. When using a pressure gauge to measure the 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 range. To ensure measurement accuracy, the minimum working pressure should not be lower than 1/3 of the 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. It should be selected according to the working pressure of the boiler. 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 working pressure of the boiler in actual operation is always lower than the rated pressure on the nameplate. This is true of industrial steam boilers and hot water heating boilers. For example, a 4t / h steam boiler has a rated pressure of 1 MPa. If the manufacturer is equipped with a pressure gauge 1.5 times, it should be equipped with a 1.6 MPa range pressure gauge. If the user needs to meet the production process under the pressure of 0.5 MPa due to the production process, at this time, when the measuring range is running, the pointer of the pressure gauge points to a position less than one-third of the measuring range. small. That is, the range of the selected pressure gauge 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 a pressure gauge equipped with it should be 1 MPa or 1.6 MPa. 1.6MPa pressure gauge. In actual operation, as long as 0.2 MPa can meet the heating requirements, the pointer of the pressure gauge points to one-eighth of the range, it is difficult to convince people of the accuracy and sensitivity of the pressure gauge. ，即在水压试验时，采用锅炉厂按额定压力配备的压力表； 6、在日常运行时按实际工作压力的2倍来配备压力表。 5. In order to solve the above problems, two kinds of pressure gauges should be used, that is, the pressure gauges provided by the boiler plant at the rated pressure during the hydrostatic test; 6. The pressure gauges should be equipped with twice the actual working pressure during daily operation. If the working pressure is 0.2MPa, a pressure gauge with a range of 0.4MPa is used. In this way, the pointer is in the middle of the dial, pointing up vertically. The seating pressure of the safety valve is also adjusted according to the working pressure, and the pressure gauge still has sufficient margin to cope with the overpressure indication.