The shut-off valve closes too slowly

Reply to 1# xubiao213: You need to specify whether it’s for on-air or off-air operation, and where the solenoid valve is installed Should it start closing after 20 seconds or close completely?

It depends on whether it’s a pressure-open valve or a pressure-close valve; if that doesn’t work, switch to a double-acting one

If it’s a newly installed valve, the air supply pressure might be low; adjust the pressure. If not, and it was working normally before, it might be that the exhaust outlet is blocked.

It closes quickly probably because the spring mechanism pushes it open, which is why it’s fast; it closes slowly perhaps because it has to overcome the force of the spring, which is why the closing process is slow

Original poster, I’ve encountered this situation before: when the shut-off valve is turned on or off, the gas inside the cylinder needs to be released through the directional valve and the silencer. In several instances I’ve faced this issue, it was due to rust inside the silencer, or sometimes there were valves present in the silencer, which prevented smooth gas release and caused the valves to open or close slowly. Try removing the silencer to see if that helps.

From the perspective of a valve manufacturer, I would guess it’s probably an actuator with spring return. Different movement speeds may be due to the following reasons: 1. The pre-tensioning force of the actuator is relatively high ； 2. It might be that the flow capacity of the intake and exhaust ports is different. Under normal circumstances, cut-off valves only have requirements regarding the speed at which faults can be resolved; therefore, valve manufacturers will choose standard piping for the intake lines, such as 1/4\" NPT-Φ8 pipes ； As for the exhaust vents, when speed requirements exist, they are made larger, such as 1/2", and exhaust is facilitated through a air control valve with a higher flow capacity. When air is drawn in, the speed of intake is slow due to the small size of the inlet, and the pressure gradually increases; the valve begins to move only when the torque exceeds the pre-tightening force. When exhausting, the spring force is high, and the exhaust port is large, allowing for rapid exhaust; therefore, the valve responds quickly. Suggestions: 1. Increase the size of the valve’s air inlet and the associated air supply pipes; this may require replacing the filter pressure regulator with a larger one. 2. When specifying requirements for valves in the future, clearly state the required operating speeds, indicating the speeds for OTS (open to shut) and STO (shut to open). (Generally, these specifications are provided by the design agency.) Avoid specifying just a general time frame, as this might lead others to assume that only the reset speed is required. This way, there will be no mistakes.

Is it an open-air situation or a closed-air one? If it’s an open-air situation, use a quick discharge valve

In reply to those above: It’s the valve that’s causing the problem. I’ve checked the exhaust port and there’s no issue with it; there’s no silencer either. The valve used to close at a normal speed, but recently it has started to close slowly – it takes about 20 seconds before it begins to close, and it takes around 10 seconds to close completely. The pressure of the air supply for the control valves is usually 4 kilograms, and even after increasing this pressure, the problem persists

It’s a gas valve that opens quickly but closes slowly. There are two possible reasons: either the gas pressure is too high, in which case it can be reduced; or the exhaust hole isn’t unobstructed and isn’t completely blocked~~~

Reply to 9# xubiao213: There seems to be a problem with the exhaust pipeline; check if there are any blockages, and inspect all the components along the exhaust pipeline.