External calibration company for instrument annual inspection, providing on-site calibration and measurement services

External calibration company for instrument annual inspection, providing on-site calibration and measurement services

The following are the general procedures for calibrating a level:

External calibration company for instrument annual inspection, providing on-site calibration and measurement services

Pre-calibration preparation

1. Check the appearance of the instrument, which should be free of paint peeling, rust, and scratches, with good sealing. The surface of the optical parts should be clean, without defects such as delamination, film peeling, oil stains, mold spots, etc.

2. Confirm that all components of the instrument are functioning properly, the motion mechanism rotates flexibly, the level is securely installed, and the bubbles move flexibly.

Measurement performance calibration

1. Calibration of circular level: Level the instrument to center the bubble, rotate the instrument horizontally 180 °, and observe whether the bubble deviates from the center of the circle. If there is deviation, use an Allen wrench to adjust the correction screw, correct the deviation of the bubble from the center of the circle by half, and repeat the operation until the bubble is centered in any direction.

2. Cross wire calibration: Align one end of the telescope wire with marker point A, tighten the brake screw, rotate the micro motion screw to move the telescope left and right, and check if point A moves on the wire. If not present, open the cover of the cross wire dividing plate, loosen the fixing screws, rotate the dividing plate seat to make the horizontal wire horizontal until point A always moves on the horizontal wire, and then tighten the fixing screws.

3. Calibration of sightline error (i angle): Set two scales A and B about 100m apart in an open field, place the calibrated instrument in the middle of the two scales for measurement, read out the elevations A1 and B1, and calculate the height difference G1. Then measure the tested instrument close to scale B, read out the elevations A2 and B2, and calculate the height difference G2. The tilt error of the line of sight should be adjusted within the allowable deviation range, that is, the difference between G2-G1 meets the relevant requirements.

4. Calibration of vertical axis operation error: For level tube level instruments, the vertical axis operation error of the calibrated instrument should not exceed 1/2 of the nominal angle value of the level tube, and subsequent calibrated instruments should not exceed the nominal value; For automatic leveling instruments, during operation, the deviation of the circular leveling bubble and the orthogonal leveling tube should not exceed 1/4 of the nominal angle value.

5. Calibration of the perpendicularity between the horizontal wire and the vertical axis of the telescope reticle: The perpendicularity between the horizontal wire and the vertical axis of the level telescope reticle should not exceed 3 '.

6. Calibration of line of sight multiplication constant error: The line of sight multiplication constant error should not exceed 0.4%.

External calibration company for instrument annual inspection, providing on-site calibration and measurement services

Post calibration processing

After calibration is completed, a calibration record should be filled out, recording information such as calibration date, calibration personnel, instrument model and number, calibration items, calibration results, etc. For instruments that fail calibration, they should be labeled as unqualified and sent to a professional maintenance institution for repair. After repair, they need to be recalibrated.