The core of maintaining and calibrating natural gas online dew point meters is "regular cleaning and protection+standardized calibration process+environmental and installation adaptation" to ensure long-term measurement accuracy. The specific methods are as follows:
1、 Daily and Regular Maintenance
Keep the sampling pipeline clean and dry, regularly check for leaks, blockages, or condensed water accumulation, and avoid contamination of sensors with oil and dust in natural gas.
Regularly clean the sampling port and filter of the dew point meter, and replace the filter element every 1-3 months according to the working conditions to prevent impurities from adhering and affecting the detection.
Avoid exposing the instrument to severe temperature changes, vibrations, or corrosive gas environments. For outdoor installation, insulation, rain protection, and dust prevention measures should be taken.
Regularly check the power supply and signal transmission lines of the instrument to ensure secure wiring and avoid data drift caused by electromagnetic interference.
For condensing dew point meters, it is necessary to regularly check whether the refrigeration system is normal and promptly clean the residual impurities in the condensing chamber; For capacitive sensors, avoid contact with liquid water to prevent sensor failure.
2、 Standardize the calibration process
Calibration cycle: Generally calibrated every 6-12 months, shortened to 3-6 months in harsh working conditions (such as high dust, high humidity, and impurities), or calibrated in a timely manner according to instrument alarm prompts.
Calibration standard: The standard dew point gas or dual temperature and dual pressure method is used for calibration. The dew point value of the standard gas should cover the commonly used range of the instrument, and the uncertainty should be better than the accuracy level of the instrument.
Calibration steps: 1. Switch the instrument to calibration mode first, ensuring that the sampling pipeline is tightly connected to the standard gas source without leakage; 2. Introduce standard gas and maintain a stable flow rate (usually 0.5-2L/min according to the instrument manual). Record the data after the reading stabilizes; 3. Compare the instrument display value with the standard gas dew point value, calculate the error, and adjust the instrument coefficient if it exceeds the allowable range; After calibration is completed, introduce dry gas to blow the pipeline and restore the instrument to normal measurement mode.
Calibration record: Detailed record of calibration date, standard gas information, calibration data, adjustment parameters, etc., establish calibration files for future reference.
3、 Key precautions
Before calibration, it is necessary to ensure that the instrument and standard gas source are in a stable working state to avoid calibration during severe temperature and pressure fluctuations.
Do not directly impact the sensor with high humidity gas. After calibration, it is necessary to thoroughly blow it with dry gas to prevent the sensor from getting damp and aging.
If the instrument experiences excessive reading drift, inability to calibrate, or frequent alarms, it is necessary to promptly contact the manufacturer for maintenance and replace aging sensors or core components.
Operators need to undergo professional training and strictly follow the instrument manual and calibration specifications to avoid human errors.