1、 Large deviation in results: Three dimensional investigation from "sample equipment operation"

The deviation of the test results exceeds the allowable range (usually carbon ≤± 0.005%, sulfur ≤± 0.0005%), and the problem needs to be gradually located according to the "sample pretreatment → equipment status → operation process".

1. Sample stage: the core cause of source error

Uneven samples and improper pretreatment are the primary factors. If there are inclusions or segregation in the sample, or if the "representativeness principle" is not followed during sampling (such as not avoiding surface oxide layers or cracks), it will directly lead to distorted test results. In addition, sample weighing deviations (such as not being accurate to 0.0001g) and abnormal addition of flux (such as excessive tungsten particles causing sulfur adsorption, or insufficient tin particles affecting combustion) can also cause deviations. During the investigation, it is necessary to recheck the appearance and weighing data of the sample, and verify the flux ratio according to the standard ratio (such as 1g sample+1g tungsten particles+0.2g tin particles).

2. Equipment stage: Key component status verification

The abnormality of the combustion system and detection system is the main equipment cause. Insufficient temperature in the combustion furnace (incomplete combustion of carbon and sulfur below 1200 ℃), insufficient oxygen purity (introduction of impurity gases below 99.99%), and clogged dust removal pipes (resulting in poor gas circulation) can all affect the efficiency of carbon and sulfur conversion; However, contamination of the infrared detection pool and aging of the filter will reduce the accuracy of signal capture. When troubleshooting, it is necessary to first check the temperature display of the combustion furnace and the reading of the oxygen pressure gauge, and then disassemble the dust removal pipe to check the dust accumulation. If the transmittance of the detection tank is lower than 80%, the lens needs to be wiped with anhydrous ethanol and recalibrated.

3. Operational stage: The importance of standardized processes

The operator's failure to calibrate the instrument according to the regulations (such as long-term failure to use standard samples for verification), setting the combustion time too short (insufficient release of carbon and sulfur), or uncleaning the sample boat (residual previous detection substances) may all lead to deviations. The solution is to calibrate with standard samples after daily startup to ensure that the test results are within the allowable error range; Strictly control the combustion time (such as setting the steel sample to 40-60 seconds), and replace the clean sample boat after each test.

2、 Instrument alarm: Accurately handle according to "alarm code - fault location"

The CS alarm of the carbon sulfur analyzer is usually accompanied by a code prompt, and the fault location should be located according to the code to avoid blind disassembly.

1. Common alarm codes and handling solutions

Low oxygen pressure alarm (code E01): First, check if the oxygen cylinder valve is open. If the valve is normal, check the pressure of the oxygen pressure reducing valve (which should be ≥ 0.4MPa). If the pressure is insufficient, replace the oxygen cylinder; If the pressure reducing valve malfunctions, it is necessary to replace the valve with a new one and readjust the pressure.

Combustion furnace over temperature alarm (code E03): Immediately turn off the heating power, check if the temperature sensor (thermocouple) is loose or damaged. If the sensor is normal, check if the temperature controller parameters have been mistakenly changed (such as setting the temperature above 1300 ℃), reset the standard temperature (commonly used for steel testing at 1250 ℃), and restart the equipment.

Infrared detection pool fault alarm (code E05): After turning off the instrument power, open the detection pool cover and wipe the infrared light source and receiving end lens with a dust-free cloth dipped in anhydrous ethanol to remove dust or oil stains; If the alarm persists after wiping, contact the manufacturer to test the light source intensity or replace the detection cell.

2. General principles for handling alarms

When encountering an unknown alarm code, first press the "emergency stop" button to cut off the power supply and avoid the fault from expanding; Refer to the "Alarm Code Comparison Table" in the equipment operation manual again to preliminarily determine the type of fault; If it cannot be resolved by oneself (such as circuit board failure), the alarm time, code, and equipment status should be recorded, and professional maintenance personnel should be contacted. Do not disassemble core components (such as infrared detection module, temperature control motherboard) without authorization.

3、 Daily Maintenance: Key Measures to Reduce Malfunctions

Whether it is result deviation or instrument alarm, most problems can be prevented through daily maintenance. Suggest establishing a "daily weekly monthly" maintenance checklist: check oxygen pressure and clean sample boats before starting up each day; Dismantle the dust removal pipe every week to clean the accumulated dust and calibrate the zero point; Verify the detection accuracy and check the aging condition of the heating wire in the combustion furnace using standard samples every month. At the same time, operators need to regularly participate in equipment training, familiarize themselves with instrument principles and emergency response procedures, shift from "passive maintenance" to "active prevention", and ensure the long-term stable operation of carbon sulfur analyzers.