Problems with double-flange level gauges
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Question 1: For a double-flange level gauge, if no capillary is used on the positive-pressure side and it is connected directly to the flange, while a capillary is used on the negative-pressure side, then there is no need for migration. Is such an application possible? Question 2: Is it okay if the table header isn’t installed in the meter box during winter? Liaoning Province.
1. The capillary also needs to migrate, right! Must the silicone oil inside not migrate? ? ……Is this to save on the flange for that section of capillary on the positive pressure side? ? I’ve never seen anything like this! 2. The header doesn’t have to be equipped with it..., but low temperatures combined with snow and rain can easily cause problems, so it’s usually installed! A protection box is sufficient; no insulation is needed! It can be used as a reference, depending on the ambient temperature and the lowest temperature that the transmitter can withstand!
Question 1: There are capillaries on the negative pressure side; even with static pressure, migration still occurs... Question 2: We are in the south, so this problem does not exist; it’s unclear whether a meter box is required or not...
No need for re-migration means that it can be migrated properly at the factory, without the need for further migration on-site, as the amount of data to be migrated has already been determined.
Question 1: Migration is still necessary, of course. Unless the height of your positive and negative pressure chambers is the same as that during calibration in the laboratory, negative migration is required! Question 2: It is acceptable to not use an instrument box, but it is necessary to ensure that the local ambient temperature remains within the operating range of the gauge; the diaphragms in the positive and negative pressure chambers need to be insulated!
Question 1: As long as it is a closed container, migration is necessary; for open containers, using double flanges is an overkill. Question 2: It is generally not necessary, but at around minus 40 degrees Celsius, even capillaries sometimes require proper insulation.
:L is speechless. . . It’s negative pressure that’s being transferred, bro – what does that have to do with the positive pressure pipe? And are you sure such a gauge exists?
I have seen this type of instrument; Rosemount can manufacture it, but I’m not sure about other manufacturers. The capillary tube should be placed on the negative pressure side. If it’s for migration, it’s definitely still necessary. As for what you mentioned regarding factory migration, if the specific and accurate range is specified in the purchase specifications, the factory will carry out the migration as required; it has nothing to do with whether it’s a single or double capillary. Meters can usually operate normally at temperatures between -30 and -40 degrees; there is no major issue if they are not equipped with a meter box.
It is not recommended to use it this way, as the thermal expansion and contraction of silicone oil in the negative pressure side capillary affects the measurement accuracy of the instrument
Question 1: If it’s an open-tank setup, there’s no problem. But in the case of a sealed tank, after installation, simply mark the zero point when there’s no water present; no need to make any adjustments. Question 2: It’s fine for the gauge head to not be placed in a gauge box during winter. Nowadays, transmitters can withstand temperatures ranging from -40 to 85°C; it’s advisable to insulate the capillary tube as well: victory: