Valves: relatively special types of failures
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An oxygen vent valve (imported from abroad) is experiencing the following issue during use: when it is not under pressure and being adjusted, its stroke and operation are all normal. However, once pressure is applied, at levels above 6.5 MPa, the valve cannot be opened fully – it can only reach about 60% of its full opening position. The valve actuator is of mechanical type; despite multiple attempts at adjustment, this problem persisted. After replacing the actuator with one from another unit in the same application, the valve worked properly for a while, but further observation is still needed. I hope experts in this field can help analyze the causes of this fault
Have you tried using the replacement locator in another location? If the same situation occurs, please set the locator parameters; if that doesn’t work, use a new one!
Is the valve stroke the same as that of the positioner? Generally, there are two types with strokes of 60mm and 100mm; as long as the stroke meets the requirements, there is no major issue.
The pressure difference before and after the valve is quite high; it is suspected to be a problem with the selection of the valve. I have encountered this phenomenon before.
It’s definitely because the air supply pressure output of the locator is insufficient; mechanical ones allow for adjustment of the zero and full-scale settings, so try adjusting those. Just adjust the gas source output. Main zero adjustment position
Insufficient air pressure: Increase the air supply pressure; the locator is misconfigured or faulty
Check whether your valves are of the FC or FO type, and whether they have two cylinders or use spring return; it’s possible that the restoring force of the spring is not sufficient. It would be best to provide a detailed introduction to the valves, with everyone under the guidance of Staff Officer Benny.
It could be a problem with the air supply pressure or the locator!
Since it is a relief valve, the pressure difference before and after the valve should be large. When set to 60 degrees, the flow rate should be high. ? Is that right?