Basic guidelines to follow when maintaining the instrument

A. Follow the one-time rule when maintaining the instrument. When the system fails, you can tentatively change some states, and you can change one parameter at a time. For example, to limit the problem of de-dimensionalization of chromatographic peaks, you can change the mobile phase, change the guard column, and change the analytical column one by one. Some simple change steps may solve the problem. B. Follow the secondary comparison rule when maintaining the instrument. A. Follow the primary rule when maintaining the instrument. When the system fails, you can tentatively change some states, and you can change one parameter at a time. For example, to limit the problem of de-dimensionalization of chromatographic peaks, you can change the mobile phase, change the guard column, and change the analytical column one by one. A few simple changes may be able to solve the problem. B. Follow the secondary comparison rule when maintaining the instrument. The fault location has been identified before the manual overhaul, or the solution to the fault has been determined. In other words, you have found the right solution before you start. For example, if the peak value of the internal standard is found to be lower during the injection process, you can repeat the injection to see how the repeatability is. If it is accidentally lowered, whether it is caused by bubbles in the loop. This rule can be used to examine the situation after the system is changed. After changing the flow direction, two standards can be injected before the formal injection to check the stability of the retention time and the stability of the chromatographic peak. If there are redundant peaks in gradient elution, you can elute once with no-load gradient (is there really a problem?), using this rule can avoid unnecessary changes and determine corrective measures as soon as possible. C. Follow the substitution rules when maintaining the instrument. Replace the suspicious parts with good ones. This is the best way to find faults. If you suspect that the detector is causing noise, replace it with a good rotorless vulcanizer detector. If the fault is eliminated, it means there is a problem with the replaced detector. The scale of the application of this rule varies from large to small, ranging from changing the entire component to changing the integrated block on the printed circuit board. D. The replacement rule should be followed when maintaining the instrument. This rule is used together with the replacement rule. After a good part replaces the suspicious part of the melt flow rate tester, the situation has not improved, and the original part should be replaced. This minimizes maintenance costs and prevents the backlog of used parts from the rotorless vulcanizer. This rule only applies to a single failure. The replacement principle does not apply to the following situations: (1) The new part is damaged when it is removed (such as the pump sealing gasket); (2) The price of the component is low (such as the column liner filter); (3) The original part is reinstalled Take the risk of damage; (4) Regular replacement parts. E. The rules of reference conditions should be followed when maintaining the instrument. There are usually two reference conditions: ①standard reference conditions; ②test reference conditions. Standard reference conditions, also called standard test conditions, are conditions that are easy to verify from one system to another, and from one laboratory to another. The data measured under this condition helps to identify problems between the actual test and the system. If the system pressure rises under certain test conditions, but the pressure is normal under standard conditions. This shows that the abnormality of the melt flow rate analyzer system is caused by the changes in the laboratory. The following table lists the standard test conditions for starting a new column. The standard test conditions can also be used to check the system during use.