Instrument air system
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The dew point after passing through the dryer is within the acceptable range, but mist appears at the bottom of the instrument air storage tank. What is the cause of this?
It’s cold in winter, and that’s completely normal. Here, during winter we usually keep the drain valve at the bottom of the air handling ducts open to about half an inch to continuously remove condensate. Also, our plant’s air compression station is part of the catalytic unit, and the purified air meets all quality standards
This is a conceptual issue related to relative humidity: when air conditioning is turned on in a room, the temperature drops, and the air conditioner needs to drain water – it’s the same principle.
To ensure that the air used in my device is of satisfactory quality, does that mean the air supplied from outside is also definitely of satisfactory quality? lol
Our one is under the Public Works Department
What is the criterion for acceptable dew point? Is it below the local minimum temperature?
General specification: -40 degrees, detectable
Yeah, that’s exactly what I mean. I’ve forgotten the specific criteria; in any case, they should be stricter than those set by the factory. Since the air compression stations, water treatment systems, gas tanks, and other utility systems here all fall under the catalysis workshop, I have some understanding of these aspects. But it’s been some time since I was working in catalysis, so I’ve forgotten the exact control criteria
The tasks in the catalysis workshop are quite heavy; generally, torches also fall under the responsibility of this workshop
If the instrument air actually contains liquid, that would be a problem, as it poses safety risks and requires close attention. The normal dew point of instrument air is -40 degrees, which corresponds to a water content of 126 ppmv. The instrument air pressure is generally 6-8 bar, and the water partial pressure can be calculated. If the ambient temperature is not too low, there should be no water condensation. It is recommended to calibrate the dew point meter with N2. I wonder where the original poster’s device is?