Determination of instrument air pressure dew point in air compressor station
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1. How is the dew point of instrument air pressure determined in an air compressor station? 2. Is the instrument air pressure determined by the pressure at the points where air is used within the plant? 3. What is the relationship between instrument air pressure and pressure dew point? 4. The chemical engineering design manual states that the dew point should be 10°C lower than the lowest outdoor temperature in the area where the plant is located. Does the dew point here refer to the pressure dew point or the atmospheric dew point?
The last edit to this post was made by 678-2 on 2017-11-9 at 11:00. Regarding your question, it is recommended that you refer to sections 4.1.3 and 4.3 of the \"SHT 3020-2013 Standards for Design of Gas Supply Systems in Petrochemical Industries\" – specifically those sections dealing with gas supply units and gas supply pressure – which will help resolve your issue. Refer to GBT 4830-2015 Industrial Automation Instruments – Pressure Range and Quality of Air Supply as well. For your reference
The dew point is generally at -30°C; it depends mainly on the local minimum temperature. Refer to the standard GB/T50029-2014 for details
1. The main purpose is to prevent condensation from damaging the instruments; generally, it is specified that the dew point of the instrument air at atmospheric pressure should be -40 degrees Celsius. 2. The gas pressure is determined by the maximum gas pressure specified by the instrument; it can be supplied at a reduced pressure or at a different pressure. 3. There is no functional relationship between pressure and dew point; instead, there is a functional relationship between dew point and temperature. As for the dew point at normal pressure and the dew point under pressure, these values can be found in tables. 4. It refers to the dew point at atmospheric pressure; “outdoor” indicates that it is at atmospheric pressure~~
It is definitely necessary to consider the pressure dew point; according to standards, this value should be 10°C lower than the local temperature. Since compressed air is transported under pressure in pipes, usually at a pressure of 6–8 kilograms per square centimeter, if the local minimum temperature is -12°C, then the pressure dew point must be at least -22°C, leaving a margin of 10°C. http://www.lnw1000.com/d/file/jishu/2017-10-11/2baa745b87dc5262e29d47398f523ded.jpg Online dew point meter: Generally, manufacturers’ dew point meters are used to measure dew point at atmospheric pressure, but the readings can be converted. Software for converting pressure dew point to atmospheric dew point: http://www.lnw1000.com/jishu/246.html http://www.lnw1000.com/d/file/jishu/2016-12-21/185a1ecb3889853a03d427b8bd9b2b9d.jpg