Pressure indication
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Dear senior, I have a simple question: for the compressor inlet here, the pressure specification is 99 kPa (gauge). I’m not sure whether, when converted to gauge pressure, it should be -1 kPa or +1 kPa Why are process parameters expressed in this way?
I mean, expressing the advantage in terms of absolute pressure means it remains constant; but if expressed using a gauge, is it vacuum or gauge pressure? I’m a bit confused; regarding the compressor, I think it should be negative – am I correct?
Gauge pressure = Absolute pressure – 101.325 kPa
Well, it’s like this: if it’s expressed in gauge pressure, it would be -2 kPa, while the vacuum level would be 2 kPa. On my end, the pressure at the other compressor inlet is -85.7 kPa (gauge). So wouldn’t the gauge pressure be -186.7 kPa? That’s not possible. I’m not sure what the problem is
I know that there are two compressors here, different ones; one has a pressure of 99 kPa(A) and the other -85.7 kPa(A). I’m not sure, but if converted to gauge pressure, wouldn’t the latter value be -186.7 kPa? That’s impossible
Another compressor inlet of -85.7 kPa(A) is definitely wrong
-85.7kpa(A) – that’s definitely wrong
-The value of 85.7 kPa(A) does not conform to physical principles; it should be G 99 kPa(A) as shown on the gauge. The value can be -1, +1, or +2, as there are variations in atmospheric pressure and the zero point of the gauge can also vary
Put simply, this refers to the situation in a vacuum: I can use the pressure inside the container itself to represent it (that is, absolute pressure). I can also use a gauge outside the container to read the value (in this case it’s gauge pressure; whether the container’s pressure is higher or lower than atmospheric pressure, I still use this value to represent it). If the actual pressure inside the container is lower than atmospheric pressure, then the gauge will show a negative value, indicating that the container’s actual pressure is indeed lower than atmospheric pressure – for example, 10 kPa. In that case, the actual pressure inside the container would be 90 kPa. If the gauge pressure is 1 MPA, then it means the actual pressure inside the container is higher than atmospheric pressure, at 2 MPA. In summary, there are two ways to express pressure: as actual pressure, gauge pressure, or as a vacuum reading. I consider actual pressure to be the pressure “inside” the container, while gauge pressure represents the pressure “outside” the container; it’s just a difference in representation! I’m not sure, am I? Feel free to point out any mistakes