ABB LS25 laser analyzer troubleshooting

Calibration: Proportional calibration and global calibration cannot be mixed

LS25 is calibrated with certified gas at the factory and usually does not require calibration upon receipt. After running for a period of time, laser aging may cause drift. It is recommended to verify annually with standard gas and calibration pool. Calibration is not recommended when the reading deviation is less than 2-3%, as this is close to the absolute uncertainty of the calibration gas itself; The instrument accuracy is about 1% of the reading (when the temperature and pressure settings are correct). The second harmonic technology itself has no baseline, and the zero point does not require calibration; If zero is forcibly marked, the software will report an error. Calibration is only allowed if the amplitude of the absorbed signal is higher than the preset level (usually 20 times the 1m optical path detection limit).

PROPORTIONAL only adjusts the proportionality constant between the peak amplitude of the absorption line and the concentration, without requiring special gas parameters or signal quality, and can be adjusted as needed on the process gas. It is possible to calibrate a specific gas separately, or use "Adjust" to automatically adjust other gases according to the proportion of the already calibrated gas. Global calibration simultaneously adjusts line width parameters and proportional constants, requiring stable and controllable reference gas, calibration pool, and certification mixture gas. Typically, nitrogen gas is used to prepare the measured gas, and dry air can be used for O ₂; Global calibration requires accurate pressure and temperature input into the calibration pool, and should be performed by experienced personnel after major repairs. Do not perform global calibration on process gases, and do not perform global calibration at low concentrations, short optical paths, or poor signal-to-noise ratios. Global calibration should only be considered after replacing the laser module, motherboard, receiver board, or adjusting the laser temperature, modulation amplitude, phase, and current.

When calibrating the pool connection, if there is flow in the gas path, the pool pressure is higher than the ambient pressure, and the pressure difference depends on the flow rate and the outlet pipe diameter and length. It is best to use an absolute pressure sensor to measure the pressure near the pool; If only environmental pressure can be measured, the airflow can be turned off and stabilized for 1 minute before calibration. Reactive and adsorbent gases such as HF, NH3, H ₂ O, HCl, H ₂ S should be treated with stainless steel tanks (PTFE for HF) and PTFE short tubes. The flow rate can be increased to 5-7 l/min, and the attenuation should be observed by turning off the flow after the concentration stabilizes; Rapid decay indicates that the pool needs to be passivated. After calibration, the settings file and reading file should be saved for easy tracking.

Quick troubleshooting of LCD error codes

The LCD of LS25 is the first diagnostic window on site. The common information and processing methods are as follows:

Low transmission: Transmission below the reliable measurement limit. First, clean the window, check for blowing, and realign it; Do not change the concentration parameters first.

Laser line up error: The laser did not hit the detector. Check for window contamination, light path obstruction, and alignment of transmission/reception.

PLC T-read error/PLC P-read error: 4-20mA temperature and voltage input current>23.7mA or<0.3mA. Check probe wiring, power supply, and range; Fixed values can be temporarily used instead.

T-read out of range/P-read out of range (warning): Current>22mA or<3.2mA, temperature and voltage may be incorrect. Check the sensor or change the fixed value.

P/T out of range (warning): Temperature and pressure compensation exceeds the acceptable range, and concentration accuracy may decrease. If the input value is correct, it indicates that the instrument is operating outside the specifications.

Ex read out of range (warning): The input current of the external gas sensor exceeds the range, check the Extra/Low current input.

Voltage supply failure: The power supply of the transmitting unit exceeds the range of 18-36V. Check the voltage drop of the power supply and cables; Repeatedly contacting the service.

Low/High laser temp (error): Laser temperature adjustment failed, instrument enters FAULT and automatically restarts after one hour. Check whether the launch unit is overheated, has heat dissipation and ventilation; Repeatedly checking electrical contacts or hardware.

Low/High box temp: The internal temperature of the transmitting or receiving unit exceeds the limit. Check the environmental temperature, thermal radiation, ventilation, and add insulation if necessary.

EEPROM error: Internal memory failure. Upload backup settings file; Repeatedly contacting the service.

Self test fail: Start self-test failed. Restart; Record all LCD information, download the Error log and System log, and contact the service.

Low/High line position, No absorption line: Spectral abnormality, possibly due to unknown interference gas, laser temperature/wavelength error, emission unit overheating, or laser malfunction. Verify by continuously running the calibration pool and appropriate concentration gas for more than 70 minutes; Still not disappearing or with obvious calibration errors, contact the service.