Issues with the range setting of gauge pressure transmitters
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The absolute pressure transmitter installed in the new unit is of the single-flange capillary type, with a range of 0–5 Kpa. The problem is that the pressure sampling point is located about 30 centimeters higher than the transmitter; what value should therefore be entered for the range? Do you need to migrate? How should it be set up correctly? Seeking guidance
Honeywell, yeah, that’s exactly what I’m struggling with too
“The problem now is that the pressure tapping point is about 30 centimeters higher than the location of the transmitter. Is there liquid in this tank? The gas pressure is the same at every point, so it doesn’t matter whether it is 30 cm higher or not. However, this application scenario is a bit strange. I assume what you have is not a gauge pressure transmitter but a single-flange level gauge; in that case, if the level is 30 CM higher, zero adjustment is required, and the area below 30 CM constitutes a blind zone.
I’m also a beginner. It involves creating a vacuum in the tank, and this is a new type of device as well; it’s indeed a gauge for absolute pressure. On-site, I observed that the transmitter was located about 30 centimeters lower than the pressure sampling point, and there was another case where it was about half a meter lower. So I would like to ask: does the capillary tube have a significant impact on the accuracy of the absolute pressure gauge? How should this situation be handled? Can it be migrated like a regular pressure transmitter? How should this situation be migrated?
It wasn’t me who chose it either! I’m also a beginner, and I’m here to ask for advice. I’d like to know how to deal with such issues – what can be done without replacing the transmitter? What are the differences between performing calibration on a gauge that measures absolute pressure and doing it on a regular gauge, and what should be taken into consideration? Was I wrong from the start? Solve doubts?
There should be no need for migration; we also have a gauge pressure meter here with a range of 0 to 160 kPa. The pressure sampling point is more than 1 meter above the meter itself, and it’s a pressure transducer of the duct type. The meter shows 98 kPa with respect to atmospheric pressure. Gauge pressure meters are used to measure gas pressure, and under normal operating conditions it displays 50 kPa
Is it measuring absolute pressure? Or is it measuring negative pressure level? No calibration is needed for measuring absolute pressure, but calibration is required for measuring negative pressure levels.
Since there is a capillary (with the gauge head 30 cm below the pressure measurement point), migration must be taken into account. If the density of silicone oil is 0.9 g/cm3, the pressure generated by it is 2.646 KPa; therefore, the measurement range of the transmitter can be set to 2.646–7.646 KPa(A). Correspondingly, the range set for the DCS is 0–5 KPa(A).
It’s a bit confusing to choose such a gauge; generally, those with capillaries are used for measuring high pressures. A pressure this low is indeed problematic. Migration is inevitable, but it’s difficult to determine exactly how much migration will occur, as the height difference cannot be measured accurately. There is also an absolute pressure of 5 kPa; make sure the gauge doesn’t show excessive readings at atmospheric pressure
Using a capillary for 0–5K gauge pressure seems a bit difficult. It might be better without a capillary. Floor 11 has already been given for relocation.