Problem of reverse installation of control valve
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I’m looking for help. Does anyone know why control valves need to be installed in reverse? That is, they’re not installed according to the standard procedure, but in the opposite direction. Why is that? Is backflow equipped with a flow meter? And how do you determine the inlet and outlet of a control valve? Are there any practical methods or theoretical approaches? Even the experienced craftsmen won’t tell me; they’re afraid of making mistakes or hiding their skills. I really don’t understand why – it’s not necessary at all. After all, they have more experience than us. It frustrates me to deal with people these days
Could you explain in more detail? Under normal circumstances, it cannot be installed in reverse.
Single-seat control valves normally operate with flow from low to high, and arrows are indicated on the valves to show this. We have used the cut-off valve installed in reverse. On the steam pipeline, it is used for purging; usually the valve is in a closed position, and it is opened during interlock operations to allow steam to flow in order to carry out purging. It is installed in reverse orientation because the pressure of the purging medium is relatively high. If installed in the normal orientation, the steam pressure would be low, and there might be a risk that the valve cannot be opened, which is why it is installed in reverse.
The post on the third floor is probably correct, because we have encountered situations in our work where the valves were installed incorrectly; as a result, the flow rate was insufficient. But no official provisions were seen.
Generally, control valves have arrows indicating the direction; installing them in the reverse orientation may allow the valve to open even when the air pressure is low.
Control valves are classified into flow-open and flow-closed types based on the direction of fluid flow. There are indicators indicating the flow direction on these valves, but in practical applications they can be installed in reverse; however, the magnitude of the unbalanced force acting on the valve core will differ.
By reverse installation, you probably mean the opening and closing of the flow, not the reverse placement of the valve core as used in the term regulating valve. The flow direction of the control valve should be installed according to the direction indicated on the valve body; otherwise, the control valve may not function properly. This is especially true for control valves with large pressure differences, as they must not be installed in the reverse direction.
This control valve is installed on the circulation return stream at the top of the pressure reduction tower. The issue arose due to the arrow on the control valve; upon closer inspection, it was found that the flow direction was from low to high. But is it possible that the arrow was installed incorrectly? If this is correct, then there’s a problem with the mid-stage circulation flow, because its arrows follow the normal direction of the process flow; however, with data flowing from high to low, it doesn’t make sense according to common logic
:) Single-seat valves generally have fluid inlet at the lower side and outlet at the higher side; make sure to pay attention to the arrow on the valve body!
It’s a single-seat valve; the direction indicated on the valve body is incorrect, so it was thought to have been installed wrongly. However, upon inspection, it’s clear that fluid enters from the lower side and exits from the upper side – this direction is opposite to that of the flow process.
If the flow direction of the control valve is installed in reverse, it can cause the control valve to vibrate again or produce abnormal noises during operation; the solution is to install the control valve in the correct orientation. This situation has been encountered before.
Check whether it is a gas release valve; if so, reversing its installation can improve the sealing effect
Most single-seat control valves have low inlet and high outlet, but some have high inlet and low outlet; these are what are known as flow-on valves or flow-off valves. The purpose of this design is to ensure that the control valve can open and close smoothly, provides good sealing, and that the arrow on the valve indicates the correct direction of flow
Check the documentation for the valve; there are technical specifications available
The pressure recovery coefficients for air-open and air-close valves are different, which results in varying flow capacities. Could it be that the valve size chosen during design was too large, causing it to operate at a low opening degree throughout?； Reduce the flow capacity of the valve by installing it in reverse. :lol