Zeroing of double-flange capillary differential pressure gauge
Thread Content
Yokogawa’s double-flange capillary gauge is used to measure differential pressure, with a range of 100+ Kpa. It is installed on the filter outlet pipeline at a height of 1.5 meters above the ground, while the positive side is installed on the filter inlet pipeline at a height of 4 meters above the ground. The extraction pump is located at the end of the outlet pipeline; the medium in question is a heavy fluid consisting of mixtures such as residue oil and bottom oil. The pipelines have a diameter of 6 inches, so blockages should not occur theoretically. Is it possible for the negative pressure reading on the gauge to be higher than the positive pressure reading? To zero the gauge using the normal method, does it involve placing the two flanges on the same level, then using 475 to perform the zeroing? After zeroing, positive and negative pressures are applied to the flanges of the pipeline respectively to eliminate the differential pressure, after which it can be put into use? If, by accident, the flanges are not at the same level and the 475 is zeroed out while there is a differential pressure, then will the baseline zero point of the gauge be lost? This could potentially prevent the gauge from functioning properly
The two flanges are on the same horizontal level, so the differential pressure should be zero. After the instrument is installed, if the flanges are not at the same level, note the differential pressure at that time before it is put into use; this value can be used as the migration amount. If zeroing is performed at 475 under differential pressure conditions, the measurement will be inaccurate; it is necessary to remove the device again to perform zeroing.
Set the range, install the zeroing mechanisms on both sides – that’s all there is to it
Actually, the original poster is correct. Why would the poster ask in that way? ? ? ? Is it meaningful for my own answer? ? ? ? ?
Because someone asked me about the principle behind this type of installation, and also why it’s not possible to reset it directly, and what the reason for that is. I can’t say, so I’m here to ask about the principle
Since the differential pressure is not zero under actual installation conditions, it cannot be reset to zero; after resetting, the displayed value might be “0”.
They are not on the same level; if the differential pressure is reset, the zero point will be inaccurate after installation, and the measurements will also be incorrect. However, it’s still possible to take measurements.
Filter differential pressure is the pressure drop resulting from fluid flow (mainly the differential pressure across the filter screen); both diaphragm cells should measure the fluid level, otherwise it becomes a liquid level measurement. The amount of migration can be estimated as follows: = height difference of 2500 mm of water column x (capillary density – medium density). The process is stopped, and it is ensured that both membrane chambers contain liquid; at this point, the differential pressure of the process is “zero”. You can read the “actual differential pressure” at this point, which is the actual amount of migration. Since there is no valve assembly, there is no other way to return to zero. @jiaguoyun
The flange at the level measurement point should be on the positive pressure side; the differential pressure range is determined based on the height. When there is no liquid level, the range is shifted to zero before the gauge is put into use. I’m not sure if this approach is correct
The flange at the level measurement point should be on the positive pressure side; the differential pressure range is determined based on the height. When there is no liquid level, the range is shifted to zero before the gauge is put into use. I’m not sure if this approach is correct