Issues with level setting of the E H servo level gauge
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The DCS configuration is set between 0–12000 mm, with liquefied gas as the medium being measured; the input density is 0.5 g/cm3. The level gauge is set such that 4 mA corresponds to 0 mm, and 20 mA corresponds to 12000 mm. When the level reaches 10050 mm, the display shows 10060 mm – there’s a difference of 10 mm. What could be the reason for this? Is it due to different densities? I would be extremely grateful if those who know could let me know!
This post was last edited by tiger2010 on 2020-5-3 05:55. The precision of milliampere current signals is limited; when the range values exceed the thousandths place, it becomes impossible for the readings on the field gauge to be exactly the same as those on the DCS
This post was last edited by sdlyml on 2020-5-9 09:08. I’ve never used a servo; since you suspect a density issue, why not try changing the density to that of water when conducting the test with water? Let’s guess: the principle behind servos is actually force balance – the pulling force of the motor plus the buoyant force equals the weight of the float. With a density of 0.5, perhaps 50% of the float’s volume is submerged in the liquid; but when using water, with the motor’s pulling force remaining unchanged, only 30% of the float’s volume is submerged. Isn’t the change in height caused by those 20% of the float’s volume that constitutes the error?
The errors are more or less the same. I remember there’s also something related to pressure compensation that needs to be adjusted during installation; I’m not sure if that’s correct. The ones from Cologne have it
That must be a measurement error. The current issue is that the liquid level readings inside and outside the unit do not match; no matter how the transmitter’s liquid level is calibrated, as long as the range is not changed, the readings inside and outside will remain inconsistent. The liquid level shown indoors is about 10 mm higher than that shown outdoors. Could it be the safety barrier? I forgot to mention that the transmitter doesn’t use a communication cable; it uses 4-20mA instead.