Pressure gauges are common in life and work. Quickly and accurately interpreting pressure gauges is the basic skill of gas distribution inspection operators. How can we read the pressure gauge quickly and accurately? In view of the phenomenon that the readings of different people differ greatly when interpreting the pointer pressure gauge, this paper analyzes the reasons for the large reading error, and gives the correct posture for reading the pressure gauge; for the phenomenon that the estimated value cannot be read, the pointer pressure is summarized. The classification of the dial is divided into three cases according to the minimum division, and the methods of correctly interpreting the accurate value and the estimated value are respectively given.
In our life, we can often see a circular watch installed on a pressure vessel or pipeline. There is a dial under the glass cover in the watch case and a pointer in the middle. This is a pointer pressure gauge. The pointer pressure gauge can intuitively detect the pressure level in the container or pipeline. Only by correctly interpreting the indicated value of the pressure gauge can the measured pressure value be accurately recorded. , the reading error should be minimized. However, it is often found in work that when the same pressure gauge has the same indicated value, the values read by different people are very different, and some cannot even read the correct value for a long time. Why? How to quickly and accurately read the indicated value of the pressure gauge?
1 Reasons for large meter reading errors
The principle of the pointer pressure gauge for measuring pressure is to use the elastic element to sense the pressure and generate a small elastic deformation, which is amplified by the transmission amplifying mechanism and converted into the rotation of the pointer shaft, which drives the pointer to indicate the pressure value on the dial. Due to the structural characteristics of the pointer pressure gauge, the reading error is inevitable. The main reasons for the reading error are as follows.
1.1 There are intervals between the scale lines of the pressure gauge dial
The rotation angle of the pressure gauge pointer is continuous, and the scale line is spaced. When the pointer is only between two adjacent tick marks, the value cannot be read accurately. The method of estimation is adopted. Different people have different reading habits, resulting in different reading values.
1.2 The reading posture of the meter reader is wrong
There is a distance between the pointer of the pressure gauge and the dial. When the meter reader observes the pressure gauge, the line of sight is directly on the dial, causing the position indicated by the pointer to change and causing reading errors.
1.3 The hands swing erratically
The pressure gauge is in a vibrating environment, the needle cannot be stably pointed to a specific position, and the reading person cannot determine the reading.
2 How to read the pressure gauge correctly
2.1 Observe the dial information
When reading the pressure gauge, you should first observe the dial of the pressure gauge to understand the range, pressure unit, accuracy level and division value of the pressure gauge. The range specifies the measurement range of the pressure gauge, and you can know whether the measured pressure is within the effective measurement range of the pressure gauge; the scale value of the pressure gauge and the pressure unit together have the actual physical meaning. The same value is expressed in different units. The pressure value of the pressure gauge is different; the accuracy grade indicates the relative error of the pressure gauge, and the maximum absolute error value of the pressure gauge can be calculated in combination with the range; the division value determines the accurate value and estimated value of the pressure gauge. Therefore, the first thing to understand when reading a pressure gauge is the above information.
2.2 Correct reading posture
For the convenience of reading the watch, the dial of the pointer pressure gauge is generally installed vertically. When reading the pressure gauge, the standing, sitting or half-standing posture can be adopted according to the height of the head to ensure that the height of the eyes and the head are roughly equal. When reading an ordinary pressure gauge, make the line of sight perpendicular to the dial, and observe the position of the pointer end corresponding to the dial scale line; when reading a precision pressure gauge, not only ensure that the line of sight is perpendicular to the dial, but also make sure that the pointer and the pointer are formed on the mirror surface of the dial. Like coincidence, observe the position of the pointer end corresponding to the dial scale.
2.3 Accurate reading of reported values
The reading of the pressure gauge consists of two parts, the exact value and the estimated value. The exact value is the value corresponding to the scale line closest to the pointer between the pointer and the 0 scale. When the same pressure gauge indicates the same pressure, the value read by different people should be the same. The estimated value is the value estimated by the person reading the meter according to the position indicated by the pointer. It is an uncertain number. When the same pressure gauge indicates the same pressure, different people may read different values.
3 points to note
3.1 Rules for reading estimates
According to the reading rules, the reading pressure of the estimated value is different depending on the division value of the meter. In general, the minimum division on the pressure gauge dial has three situations, namely, the minimum division is "1" (such as 0.001, 0.01, 0.1, 1, 10, etc.), and the minimum division is "2" (such as 0.002, 0.02, 0.2, 2, etc.), the minimum division is "5" (such as 0.005, 0.05, 0.5, 5, etc.).
When the minimum division is "1", it is generally estimated according to one tenth of the minimum division value, and the estimated value is the next digit of the accurate value. For example, for a pressure gauge with a range of 0 to 40 MPa and a division value of 1 MPa, the measurement error appears at the tenth of MPa, which is estimated to be 0.1 MPa.
When the minimum division is "2" or "5", it is generally estimated at one-half or one-fifth of the minimum division value, and the estimated value is in the same position as the exact value. For example, a pressure gauge with a range of 0 to 10 MPa and a division value of 0.2 MPa, the measurement error appears in the tenth of MPa, and if it is estimated to be in the tenth of MPa, if it is less than half a grid, it should be discarded. If it exceeds half a grid, it should be estimated. , in MPa, the numbers on the tenths may be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. For example, a pressure gauge with a range of 0 to 1 MPa and a division value of 0.005 MPa, the measurement error appears in the thousandth of MPa, and the thousandth of MPa is estimated, and the estimated reading is a few-fifths of a small grid. When the unit is MPa, The numbers at the thousandths place may be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.
3.2 Reading the pressure gauge with pointer shaking
When the pressure gauge is in a relatively static environment, its pointer indication is relatively stable, and the reading is very convenient. If the pressure gauge is in a vibrating environment, its needle may vibrate. At this time, the amplitude of the pointer shaking should be observed, and the pressure value should be the value corresponding to the middle position of the pointer shaking.
The pressure value displayed by the pointer pressure gauge is very intuitive, but accurate reading is very important. It is necessary to follow the reading rules and adopt the correct reading method, and long-term training can master the skills of fast and accurate reading.
