Pressure gauge calibration and verification

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This post was last edited by Wang Tianze on 2016-3-24 at 15:24. How to verify and calibrate pressure gauges? Regular calibration items and requirements for pressure gauges: 1. Visual inspection 1.1 The components of the pressure gauge should be firmly assembled, with no signs of looseness. 1.2 The newly manufactured pressure gauge should be smooth and even, with no obvious peeling. 1.3 Pressure gauges shall be equipped with safety vents, which must have dust protection devices. (Except for pressure gauges in which the medium to be measured is not allowed to overflow beyond the gauge face.) 1.4 The dial of the pressure gauge shall bear the following markings: manufacturer or trademark ； Product Name ； Unit of measurement, mark and number of the license for manufacturing digital measuring instruments; vacuum gauges should indicate “-” or “negative”, accuracy class, and serial number. 1.5 In the reading section, the gauge glass should be colorless and transparent, without any defects that could interfere with reading. The dial should be flat and smooth, with all markings clearly visible. 1.6 The pointer tip should cover 1/3 to 2/3 of the length of the shortest division line, and the width of the pointer tip should not be greater than the width of the division line. 1.7 The accuracy classes are 1, 1.6, 2.5, and 4. 1.8 Zero position: For pressure gauges equipped with a stop pin, the pointer should be close to the stop pin when there is no pressure or vacuum, and the “compression” should not exceed the allowable error value specified in Table 1. For pressure gauges without a stop pin, the pointer should be within the zero mark when there is no pressure or vacuum, and the zero mark should not exceed twice the absolute allowable error value specified in Table 1. For those who need to communicate, please contact: 4000-1919-15. 2. Measuring instruments: 2.1 The absolute value of the allowable error of the standard instrument shall not be greater than 1/4 of the absolute value of the allowable error of the pressure gauge being tested. 2.2 Standard instruments include spring tube precision pressure gauges and vacuum gauges, piston pressure gauges, and piston vacuum pressure gauges. 2.3 Auxiliary equipment includes pressure calibrators and vacuum calibrators. 2.4 The environmental conditions are a temperature ranging from 15 to 25°C, with a relative humidity not exceeding 85%. The environmental pressure is atmospheric pressure, and the pressure gauge should be left in said environment for at least 2 hours before it can be calibrated. 2.5 The working medium required is a pressure gauge with a maximum measurement limit of not more than 0.25 MPa; the working medium should be clean air or a gas that is non-toxic, harmless, and chemically stable. Gauges with a measurement lower limit of not more than (0.25~250) MPA, using non-corrosive liquids as the working medium. 3. Calibration of indication error, return error, and tap displacement 3.1 Method for calibrating indication error: The indication of a pressure gauge is calibrated using the scale markings with numbers on them. During calibration, the pressure is increased (or decreased) gradually and steadily. Once the indicated value reaches the upper limit of measurement, the pressure source is disconnected; the gauge is then held under pressure for 3 minutes. After that, the pressure is decreased (or increased) steadily in the reverse order, following the same calibration procedure. 3.2 Indication error: For each calibration point, during the voltage-raising (or voltage-lowering) and voltage-lowering (or voltage-raising) calibrations, the difference between the readings on the front and back of the gauge case and the reading of the standard instrument shall meet the requirements specified in Table 1. 3.3 Return error: the absolute value of the allowable error specified in Table 1 when measuring the same point during voltage increase (or decrease) and voltage decrease (or increase). 3.4 For tap displacement, when checking each point, the change in the reading caused by tapping the case lightly during voltage increase (or decrease) and voltage decrease (or increase) shall not exceed 1/2 of the absolute value of the allowable error specified in Table 1. 4. Calibration method for vacuum pressure gauges 4.1 When the upper limit of pressure measurement is (0.25~250) MPA, the vacuum section is calibrated; when the system is evacuated, the pointer should point to the vacuum section. 4.2 When the upper limit for pressure measurement is 0.15 MPa, the vacuum section is calibrated at two indication points. 4.3 When the upper limit for pressure measurement is 0.06 MPa, three reading points are checked for the vacuum section. `