Detailed explanation of pressure gauge calibration technology
1、 Preparation before calibration
1. Selection of standard instruments
-Select a standard pressure source with an accuracy level at least twice that of the calibrated gauge (such as a 0.05 level piston pressure gauge or digital pressure calibrator)
-Supporting equipment includes: pneumatic/hydraulic pump, precision connecting hose, temperature compensation device, insulated gloves and goggles
2. Environmental condition control
-Temperature control within the range of (20 ± 5) ℃, humidity ≤ 80% RH
-Avoid vibration sources (such as air compressors, mechanical processing equipment) and electromagnetic interference
-Establish a constant temperature laboratory or use an anti vibration table
3. Preprocessing by the school schedule
-Appearance inspection: Confirm that the dial glass is intact, the hands are flexible, and the seal is intact
-Cleaning treatment: Wipe the case and interface with alcohol
-Temperature balance: Place the pressure gauge in the calibration environment for at least 2 hours
2、 Calibration Implementation Process
1. Zero point calibration
-Slowly reduce the pressure to -10% FS and maintain it for 30 seconds before returning to normal pressure
-Record zero point indication error: Δ=| P displayed - P standard|
-The allowable error is calculated according to the formula: δ ≤ (MPAE × P range)+0.0025MPa
2. Range calibration
-Boost rate control: 0-40% FS ≤ 10kPa/min, 40-100% FS ≤ 5kPa/min
-Voltage stabilization time: Spring tube type ≥ 30s, digital type ≥ 10s
-Return calibration should cover the main detection points and observe hysteresis errors
3. Temperature correction
-Compensation formula for temperature difference every 10 ℃: Δ P=α · P ·Δ T (where α is the material's coefficient of linear expansion)
-Preheat the system for at least 15 minutes under high temperature conditions
3、 Data recording and processing
1. Error analysis method
-Maximum allowable error (MPE)=± (accuracy level% x range+reference value)
-Example: Level 1.6 0-1.6MPa meter, MPE=± (1.6% × 1.6+0.025)=± 0.047MPa
4、 Typical problem handling
1. Common fault diagnosis
-Linear out of tolerance: deformation of the spring tube or wear of the transmission gear
-Zero drift: spring elastic fatigue or demagnetization of magnetic steel
-Excessive hysteresis: abnormal viscosity of damping fluid or piston jamming
2. Adjustment method
-Mechanical watch: Bending adjustment screw correction linear error
-Digital table: Input calibration parameters for software compensation
-Modular table: replace sensitive component components
5、 Certification and Identification Management
1. Paste the calibration label containing the following information:
-Calibration date, validity period (usually 1 year)
-Calibration institution qualification number
-Traceability number of standard instruments
-Environmental condition record (temperature and humidity)
2. Issue calibration certificates that comply with ISO/IEC 17025 standards
6、 Special media processing
1. Corrosive media (such as Cl ₂)
-Adopting diaphragm isolation technology
-After calibration, nitrogen purge the pipeline ≥ 3 times
-Dry nitrogen maintenance during storage
2. Viscous media (such as heavy oil)
-Configure heating sleeve to maintain (50 ± 5) ℃
-Immediately flush the pipeline with kerosene after calibration
-Conduct a full-scale cycle test once a month