Issues with removing the diaphragm head of control valves
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May I ask, when removing the actuator (diaphragm head) of a pneumatic diaphragm valve, is it necessary to provide space for core extraction? In other words, does the space above the valve body need to be large enough for such extraction?
Generally, at least 200 mm of space is required; the specific amount depends on the valve parameters
It’s not necessary. There is a detachable clamp-type fitting with internal threads (male and female threads) between the valve stem driven by the diaphragm head and the valve stem of the lower control valve.
It’s not necessary, but space must be reserved; sufficient space is required if the valve internals need to be removed
Does a damaged valve core require core extraction?
This post was last edited by ylb913 on 2016-12-14 at 16:46. I hadn’t paid much attention to this issue before; it’s only now that I understand it. It is quite common for control valves to disassemble due to potential failures; in the vast majority of cases, this disassembly occurs at the valve cover of the control valve, and as it does so, the valve stem becomes separated from the valve seat. Then check whether there are any problems with the valve seat and valve core. The most common problems I’ve encountered since then have been blockages caused by slag and the like; followed by issues at the bottom of the valve seat (which isn’t relevant for widespread application). If it is assumed that the valve core is faulty and needs to be replaced, this is done only after the entire assembly above the control valve’s cover is removed. In such cases, it is necessary to check whether there is a threaded connection between the valve core and the valve stem, which determines whether the lower part of the valve stem also needs to be replaced. However, in cases where it is necessary to pull out the valve stem, I think it should also be pulled out from the bottom.