Why does the valve move slowly when it opens?
Thread Content
Three-way valve, Yamaki AVP100 actuator, air-actuated valve. It operates normally when turned off, but moves slowly when turned on; it takes 30 seconds to go from fully off to fully on. It feels like the air is moving out very slowly inside. What’s going on? How should it be handled?
1. Does removing the silencer from the locator’s exhaust port improve things? 2. If it was fast before but slow now, check whether the packing gland is dirty or blocked. 3. If the speed remains low, a spring can be considered for adding to the die head
Where is the exhaust vent silencer located? I’ll go check it in a bit. It’s probably not a paralysis issue, because I cut off the instrument air, and it can be fully opened with normal operation.
As you said, it should be a gas shut-off valve; the valve opening works fine, so it’s probably not a problem with the gas supply. Check whether there is air leakage in the cylinder, or if the pressure of the gas supply is too low, making it difficult to overcome the spring force and thus slowing down the process.
1. If the ambient temperature is low, it is suspected that the dew point of the instrument air is not within acceptable limits, resulting in water in the cylinders. Solution: Install electric heating elements at the cylinders. 2. At midnight, replace a valve positioner to check whether the valve is functioning properly. 3. Are the exhaust vents unobstructed?
It’s a gas shut-off valve; closing it works fine, but it opens slowly – you’re looking at it in the wrong direction.
Where is the exhaust vent? I only heard the sound of exhaust; I looked around but couldn’t find it. Is it inside the locator? Should we disassemble the locator?
Insufficient spring preload or slow exhaust from the actuator
The most likely reason is that the packing has aged and tightened, causing friction to slow down the rise of the valve stem.
They are all experts; the simplest solution is to replace the locator. If it works after the replacement, then it is a problem with the locator; if it still doesn’t work, then it is a problem with the packing or the actuator