Discussion on the use of EJA Yokogawa differential pressure level gauges
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I would like to ask: for Yokogawa differential pressure level gauges, when they are first installed and put into use, should the range be set first or the zero point adjusted first? What’s the difference? Also, how is the migration range set?
Before installing the transmitter, it is first calibrated according to its range; after installation, the zero point is adjusted using zero adjustment or offset adjustment....
This post was last edited by nckly on 2016-4-25 at 20:39. In the case of differential pressure using a diaphragm cell, after installing the double-flange diaphragm cell, the pressure difference is zero when no pressure is applied; the range is approximately zero. If calculations are to be done, the value should be set based on the distance between the upper and lower flanges; generally, the density of silicone oil used inside the diaphragm box is 1. If one uses custom-made pressure transfer pipes, the calculations should take into account the density of the medium involved, with negative migration being indicated in such cases
First set the range, then install it on the double flange and transfer it; it should display 0 when there is no liquid level
At zero point, when the differential pressure is zero, is 4mA outputted? Migration refers to the shift of the zero point; after negative migration, the zero point corresponding to that liquid level still results in 4mA being outputted. It is necessary to make a clear distinction.
First, set the zero point, then calculate the range based on the measurement height and the density of the medium. Generally, these settings are already adjusted at the time of ordering, so it can be installed and used straight away. Negative migration mainly applies to differential pressure gauges with pressure lead pipes; with double flanges, the installation height of the transmitter can be adjusted, so negative migration is not necessary!
If it is a double-flange level gauge, negative migration should be performed first; zero adjustment is not recommended. Use ρgh to calculate the negative migration amount, where ρ is the density of silicone oil. The range span is also calculated using ρgh, where ρ is the density of the medium being measured.
Can we zero it out after installation, and then adjust the range based on how much it has been moved?
It’s a double-flange differential pressure level gauge. I first attach the upper and lower pressure sensing diaphragms, then adjust the zero point, and after that set the range. However, setting it to the original range isn’t correct; account also needs to be taken for drift. I’m not sure what calculations are required
Is migration just changing the range again? Reset to 0?