Double-flange diaphragm level gauge
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The existing double-flange level gauge on the measurement tower gives readings that are higher than the actual value. When the front hand valve on the flange was closed and the system was drained, it was found that the level gauge showed 100% only. The diaphragm on the high-pressure side is fine; I would like to ask whether the diaphragm on the low-pressure side might be damaged or have some other issue. Currently, the flange on the low-pressure side cannot be removed. Seek the reasons together. I still have one thing I don’t understand: how does the range of a double-flange level gauge correspond to that of an on-site magnetic flap level gauge? For example, if our on-site magnetic flap level gauge has a range of 3.5 meters, what value in mmH2O does that correspond to for the transmitter? And how should the transmitter’s range be set?
There are hand valves and they are all closed; the low-pressure measurement flange cannot be removed. What’s going on?
The range of a double-flange transmitter is related to the distance between the two flanges (or the distance from the highest liquid level to the lowest liquid level) as well as the density of the medium; it has no inherent connection with the magnetic level indicator on site!
Does it show 100% when both the high-voltage and low-voltage sides are empty?
I didn’t understand the first question; as for the second question, the relationship between the remote liquid level and the on-site magnetic flap depends on the installation conditions at the site.
The range for setting the double-flange level gauge is as follows: If the height of the upper and lower flanges is H, the density of the medium is ρ1, and the density of the silicone oil filling the capillary is ρ2, with g being the acceleration due to gravity, then the range for setting the level gauge is from 0 to ρ2*H*g, up to (ρ1-ρ2)*H*g
For double-flange level measurement, migration must have occurred. If the upper range limit is less than 0, then when it is removed the reading will be 100%; this confirms that there is basically no problem with the gauge itself. However, it is not possible to determine whether the diaphragm on the upper flange is in good condition or not – removal is necessary to find out. The measurement values here are on the high side; it is necessary to determine whether the range setting is correct Is there a discrepancy between the density specified in the design and the actual value?
But both the high and low voltage readings are showing zero; it should display zero
It is recommended that the original poster take a close look at the on-site volume of the instrument technician’s question bank – you still haven’t understood the principle behind using double flanges for liquid level measurement.
It’s not like that; when measuring high and low pressures relative to the atmosphere, it also depends on your installation location. Due to the weight of the silicone oil, if there is a difference in pressure between high and low pressures, there will be a differential pressure caused by the weight of the silicone oil.