First, the appearance check
1. The newly manufactured pressure gauge should be even and smooth without obvious peeling.
2. The assembly of pressure gauge parts should be firm and free of looseness.
3. The pressure gauge index plate should have the following signs, manufacturing unit or trademark; product name; measurement unit and digital measuring instrument manufacturing license mark and number, vacuum table should have "-" or "negative" sign, accuracy Grade, factory number.
4. The pressure gauge should have a safety hole, and the safety hole must have a dustproof device. (Except for the pressure gauge outside the meter that is not allowed to be tested)
5. The pointer indication end should cover 1/3~2/3 of the length of the shortest index line, and the width of the pointer indication end should not be greater than the width of the index line.
6, the reading part, the pressure gauge glass should be colorless and transparent, there should be no defects that hinder the reading. The indexing plate should be flat and clean, and the signs should be clearly identifiable.
7. Zero position, pressure gauge with stop pin. When there is no pressure, the pointer should be close to the stop pin. The “retraction” should not exceed the allowable error value specified in Table 1. The pressure gauge without stop pin, when there is no pressure. The pointer shall be within the zero mark, and the zero mark shall not exceed 2 times the absolute value of the allowable error specified in Table 1.
8. Commonly used accuracy levels are ±1% FS, ±1.6% FS, ±2.5% FS, ±4% FS.
Second, measuring instruments
1. The working medium requirement is a pressure gauge with an upper limit of not more than 0.25 MPA. The working medium is clean air or a non-toxic, harmless and chemically stable gas. The pressure gauge with a lower limit of measurement not greater than (0.25~250) MPA, the working medium is a non-corrosive liquid.
2. The environmental conditions are such that the temperature is between 15 and 25 ° C and the relative humidity is not more than 85%. The ambient pressure is atmospheric pressure, and the pressure gauge should be at least 2H in the above environment for verification.
3. The absolute value of the allowable error of the standard gauge should not exceed 1/4 of the absolute value of the allowable error of the gauge.
4, standard equipment available spring tube type precision pressure gauge and vacuum gauge, piston pressure gauge, piston vacuum gauge
5. Auxiliary equipment, pressure calibrator and vacuum calibrator.
3. Verification of indication error, return error, and tapping displacement
1. The method of indication error verification, the indication test of the pressure gauge is carried out according to the index line marked with numbers, and the inspection gradually gradually boosts (or depresses). When the indication reaches the detection upper limit, the pressure source is cut off. Withstand voltage of 3MIN, then smoothly step down (or boost) back to the original checkpoint.
2. Return error, absolute value of the allowable error specified in Table 1 for the same point check timing, during boost (or buck) and buck (or boost) check.
3. Tap the displacement. For each point check, during the step-up (or buck) and buck (or boost) check, the indication change caused by the light case is not greater than the allowable error specified in Table 1. 1/2 of the value.
4, indication error, for each verification point, Ai Chi Mall reminds you that in the boost (or buck) and buck (or boost) check, the front and back of the lightweight case and the standard value The difference should meet the requirements of Table 1.
Fourth, pressure gauge verification method
1. When the upper limit of pressure measurement is 0.06MPA, the vacuum part is checked for three points.
2. When the upper limit of pressure measurement is 0.15MPA, the vacuum part is checked for two points.
3. When the upper limit of pressure measurement is (0.25~250) MPA, the vacuum part is verified. When the air is empty, the pointer should point to the vacuum part.
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