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For the gas path part, the phenomenon of faults that are easy to occur can be divided into three categories:
(1) Flow regulation failure; (2) Airway leakage failure; (3) Airway blockage and pollution failure.
Gas Chromatography Instrument Troubleshooting
For the gas path part, the phenomena that are easy to occur can be divided into three categories: (1) flow regulation failure; (2) gas path leakage failure; (3) air circuit blockage and pollution failure. Among the various faults that appear in the gas chromatograph, a considerable part of the gas sensor is related to the humidity sensor probe, stainless steel electric heating tube, PT100 sensor, fluid solenoid valve, cast aluminum heater, heating coil, therefore, understanding and familiarity with gas Road failure is very necessary
1, the flow can not be adjusted
(1) Visual inspection: First check the instrument system for obvious air leakage. When there is a large leak in the gas path of the instrument system, it is likely that the flow rate will not be adjusted. If you can't hear the leak, turn it to (3).
(2) Checking the leak: After hearing the leaking sound, it can be gradually positioned according to the direction in which the sound is emitted. At this point, the application of the soap can be used to further determine where the leak occurs. Find the cause and plug it in time 10ml precision Gas Chromatography vials
(3) Pre-column pressure observation: Observe the numerical value of the column front pressure indication table, which can quickly determine whether it is caused by the gas source or the internal airway blockage and damage of the instrument. If the pre-column pressure is too low (precisely lower than the predetermined pressure value during normal flow operation), then the gas source needs to be inspected; if the pre-column pressure is normal, the instrument's internal gas path needs to be checked.
(4) High pressure inspection of the cylinder: After opening the cylinder valve, observe the indication of the high pressure gauge, the pressure should be between 1 and 15 MPa. If the pressure is below 1 MPa, the cylinder is deactivated and the air is ventilated; if the pressure is within the proper range, the cylinder pressure is normal.
(5) Low-pressure output check on the pressure-reducing valve: Adjust the pressure-reducing valve to see if the indication of the low-pressure gauge on the cylinder can be adjusted to 0.25~0.6MPa. If it is normal, it may be suspected that the pneumatic filter joint is clogged or there is a problem with the stability valve on the instrument. In this case, it should be carried out according to (6); if the low pressure value is not normal, the pressure reducing valve has a problem and needs to be carried out (7) Repair
(6) Filter blockage and pressure regulator check: Slowly unscrew the connector exiting the filter outlet to the instrument air source to see if there is a strong airflow running out of the joint. If so, the filter is not blocked and the regulator valve may be defective. After confirming that the regulator valve is not out of gas, valve disassembly and cleaning can be performed, which may be caused by blockage between the valve needle and the valve seat in the regulator valve. If the valve still does not work properly after cleaning, zui should change a new valve; if there is no strong airflow flowing out of the unscrewing joint in the above test, it is necessary to check the possible blockage before and after the filter inlet; of course, the blockage of the intermediate pipeline is also Possible, but the incidence is very small 10ml precision Gas Chromatography vials
(7) Repair of the pressure reducing valve: After the structure of the pressure reducing valve is known, the pressure reducing valve can be removed and repaired. Since there is a high pressure on the inlet side of the pressure reducing valve, it is not necessary to disassemble blindly if there is no repair experience. If conditions permit, it is recommended to switch to a new valve; when changing the valve, it must be noted that the hydrogen or oxygen meter should be used separately from the pressure reducing valve used in other air source meters. The special name of the gas source should be indicated on the pressure reducing valve.
(8) Deactivation, ventilation: When the pressure of the cylinder is too small, it should be immediately deactivated, replaced with a new one or inflated. Under too small a pressure, not only the gas source output is unstable, but also the impurity concentration in the gas source will increase significantly, which is particularly disadvantageous for high sensitivity analysis. Another problem that must be noted is that the residual gas in the cylinder, especially the residual gas in the hydrogen cylinder, cannot be discharged casually.
(9) Remove the column inlet gas path: Remove the gas joint at the column inlet and observe whether the rotor in the flow meter can rise to the upper end of zui. If it can be raised to the upper end of zui, the gas path in front of the column is normal, and it is transferred to (10) for further inspection. If the rotor does not reach the upper end of the zui, the gas path in front of the column is blocked, and (13) inspection is required.
(10) Remove the column end: After connecting the column inlet back to the original gas path, remove the column outlet side joint, and observe whether the rotor in the flow meter can be adjusted to a predetermined value. If it is possible, it will judge that the pipeline and detector behind the column are blocked, and it needs to be treated according to (11); if the rotor is still not adjusted, it can be considered that the column is too tight, and it is required to press (12).
(11) Blockage inspection and elimination: Queue and clean when it is judged that the pipeline or detector is blocked after the column.10ml precision Gas Chromatography vials
(12) The column packing is too tight: the main reason for the column packing being too tight is that the carrier mesh is too large, causing excessive gas resistance. The flow rate can be adjusted to a predetermined value after appropriate use of a smaller number of carriers or by shortening the length of the column.
(13) Remove the flow meter outlet gas joint: After unscrewing the gas flow at the outlet end of the rotameter, observe whether the rotor can rise to the high end of Zui. If it is OK, it is determined that the injection and vaporizer air circuit are blocked, and the treatment is carried out according to (14). If the rotor still cannot rise to the high end of Zui, the flow valve may be damaged or the flowmeter inlet pipe may be blocked. Press (15).
(14) Plugging of the inlet: The clogging of the injector can be carried out according to the cleaning procedure of the syringe.10ml precision Gas Chromatography vials
(15) Flow valve and pipeline blockage: It will be quickly determined whether the flow pipeline is blocked by segmentation test. If yes, follow the cleaning of the gas pipeline; if the pipeline is normal before the flowmeter, the flow control valve can be removed for cleaning.
2, the flow is too big to adjust
If the gas flow rate is always large and cannot be reduced, it can be considered as a malfunction of the pneumatic control system. There are three reasons for such failures: *, there is a leak in the gas path after the flow meter; second, the gas path is too small; and third, the flow control valve is damaged. The inspection method is as follows: first block the gas outlet of the detector and observe whether the rotor in the flowmeter can be lowered to zero. If it cannot be reduced to zero, it is necessary to consider the inspection of the leaking gas. For the specific method, see the inspection and elimination of the gas leakage; if the rotor can be lowered to zero, the system will not leak. At this time, it should be observed whether the flow rate has a large change when the flow regulating valve rotates. If there is any change, the gas path air resistance can be appropriately increased; if there is no change, the valve member itself should be suspected to be in problem, and the cleaning part of the valve member should be treated. The treated valve parts should be reinstalled into the original gas path for control test.10ml precision Gas Chromatography vials
This is the end of the introduction of Gas Chromatography Instrument Troubleshooting. I hope it can help you.
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