Reinstalling the valve: how to achieve the ideal preload value
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This post was last edited by moshou1415 on 2016-6-15 at 23:34. There is a single-seat Globe diaphragm control valve that has been completely disassembled and now needs to be reassembled. So, what method should I use to install the valve core, valve stem, and cylinder push rod (with Haf coupling blocks), in order to ensure that the pre-tightening force of the valve meets the requirements specified at the time of manufacture or during use? Is there any specific metric for this (such as the distance of the cylinder push rod, pressure, etc.)? ? ? ) Please ask an expert to resolve this doubt
This post was last edited by moshou1415 on 2016-6-15 23:35. Can I do this: Fill the cylinder with air, and after the push rod has stopped moving downward completely, mark the part of the push rod that is exposed outside the cylinder. After the valve core, valve stem, and push rod have been installed, operate the cylinder again to mark the portion of the push rod that extends outside the cylinder. The two markings show a distance difference; would a pre-tightening force of 2-3 mm be sufficient? ? ?
When you were taking it apart, didn’t you check how long the screws at the connection points were, and how many threads there were?
1. To achieve performance equivalent to that of the original unit, it is first necessary to know what characteristics the original unit has. 2. In cases where the original performance is not available, an effective approach is to conduct tests and make recordings based on predetermined criteria and established methods before disassembly. 3. After reinstallation, tests are carried out using the same methods, and the results are compared; performance that is superior to that before disassembly serves as the basis for evaluation. 4. In the owner’s example, size is not the only factor to consider; the torque required to operate the valves, the time taken to complete one full cycle of opening and closing, and the consistency of performance at different opening degrees also need to be evaluated. 5. To check the torque, one method is to reduce the air pressure supplied to the diaphragm gauge in order to determine the minimum air pressure required to activate the valve
;For professional tasks, it’s necessary to find skilled technicians or send some photos for analysis. Help is available at http://www.tc29.net/gsjj/index_3.html