I. Gas chromatographic failure analysis basis
1. Understand the relevant components of gas chromatography;
2. Familiar with the role of various parts of the gas chromatograph;
3. Know how each part of the GC works.
4. Can clearly distinguish whether the work of each part is normal or not;
5, to strictly follow the relevant regulations overhaul, understand the maintenance process should pay attention to matters.
Second, failure analysis ideas
1. The problems that should be paid attention to during overhaul: It is necessary to have safe electricity knowledge, pay attention to self-protection awareness, and prevent the occurrence of electric shock accidents;
2. Determine the parts and factors associated with the fault based on the occurrence of the fault phenomenon;
3, pay attention to maintenance methods, do not easily disassemble and replace components, so as not to expand and transfer the fault range;
4, the failure analysis ideas and methods:
(1), sequential reasoning: Reasoning, checking, and searching for causes of failures based on working principles;
(2) Segmentation elimination method: Exclude one by one and narrow down the scope so as to find the cause of the failure;
(3) Empirical reasoning: accumulate according to maintenance experience to determine the cause of failure;
(4) Comparative inspection method: Refer to the relevant data of the normal machine to determine the fault point;
(5) Comprehensive method: Use the above methods in a comprehensive manner until the fault source is found.
Third, the type of gas chromatography failure
1. Faults in the gas path: gas input is not normal, the type of gas is not right or purity is not enough, gas leakage, gas blockage, gas path pollution, gas circuit component failure, improper flow setting, column problems, etc.;
2. Part of the host circuit is faulty: the startup or initialization is abnormal, the temperature control is partially faulty, the keyboard or display is partially faulty, the door is not normal, the range attenuation is not properly set, and other functional faults.
3, the detector output signal is not normal: no signal output, zero offset of the output signal, the output signal is not stable, the value of the input signal is not equal;
4. Other faults: abnormal gas source, abnormal grid voltage, abnormal secondary instrument, mechanical failure, etc.
Fourth, the fault diagnosis
1. Basics: The basis for checking the causes of failures is to fully understand the method of gas chromatography fault discrimination. The basis for mastering the fault diagnosis method is to familiarize with and understand the composition, function and working principle of each part of the instrument;
2. Inputs and Outputs: Each part, component, and even part of each instrument usually has its input and output. Input generally refers to the premise of normal operation of the part, and output generally refers to the role played by the part. Features.
For example: FID amplifier its input is the FID detector through the ion signal line over the micro current signal, the amplifier's operating voltage, and the amplifier's zero potentiometer; its output is amplified and sent to the secondary instrument electrical signal . The method of determining whether the amplifier is working properly is:
A: If the input is normal and the output is abnormal, the fault must be in the amplifier itself.
B: If the input and output are normal, the amplifier is normal;
C: If the input is abnormal, the amplifier cannot be judged normally.
3. Collection and accumulation: Actively collect maintenance data, make maintenance records carefully, and constantly accumulate methods and experiences for identifying various types of faults, and understand, familiarize, master, and keep these methods and experiences in mind.