application
Whether you are using new and outstanding products or using traditional products, you must consider the following:
1. The proportion of the process;
2. 0% and 100% accurate positioning;
3. The specific gravity of capillary filling liquid or sealing liquid (pulse tube);
4. Vertical height of capillary or pulse piping;
5. Accurate positioning of the transmitter relative to the container;
6. The vertical distance between the flanges.
Depending on the specific application, the container may open (reference pressure) or close (at some shock pressures).
Raising is often used when the container is closed. To reference shock pressure, low-end wet tubes or remote seals must be used. The low pressure creates an opposing force on the transmitter, which is the result of multiplying the specific gravity of the fill fluid by the vertical height.
Suppression is a positive pressure developed at the high end of the transmitter, usually due to the zero point above the transmitter. It is generally used at the reference atmospheric pressure of an open container. This is a positive pressure, which is the result of multiplying the specific gravity of the fill fluid by the vertical distance between the zero point and the transmitter.
The increase/suppression distance is usually inconsistent with the P&ID because the actual pipeline (or remote seal capillaries) does not all form a precise angle in the field. In most cases, the exact vertical height is not known until after the unit is installed.
Range is the result of multiplying the specific gravity by the vertical distance of the process: Figure 1. 10.5x0.9 = 9.45 mH2O (31.5 inH2O).
The correction range is to consider positive and negative pressures in the calculated 0 and 100%. In Figure 1 it looks like this:
0% = H - L
(4.5×0.8) - (15×0.8)
3.6 - 12 = -8.4 mH2O (-28 inH2O)
100% = H-L
(4.5×0.8) + (10.5×0.9) - (15×0.8)
3.6 + 9.45 - 12 = 1.05 mH2O (3.5 inH2O)
Correction range:
-8.4 to 1.05 mH2O (-28 to 3.5 inH2O)
The information required to perform calculations is not readily available. It is in the supplier's manual and P&ID, but it is not known until the unit is actually installed, because the process line and the capillary do not constitute a predetermined angle on site.
solution
DPharp has a smart level setting function that does not require an increase/suppression operation and the setting becomes faster and easier.
Only need to complete the correction through the following four steps:
1. Set the range for the process using BT200 in C21:LRV and C22:HRV, and set the value of height x specific gravity to 0~9.45mH2O (0~31.5inH2O).
2. Install the prss using a capillary or pulse tube.
3. Set the zero point (4mA) for the process.
4. Execute H10:Auto LRV via the BT200 on the H:AUTO SET menu.
DPharp calculates all boosts/suppressions and automatically sets the device for installation. It can even correct the software values ​​on C21 LRV-28 and C22 HRV 3.5 so that customers can print and record the actual configuration of their maintenance documents.
One question is, why can't we make zero settings for the process? The user has completed the installation, the fluid is now in the container, and the output of the transmitter does not match the user's sight glass. What should I do?
Most transmitters can only be adjusted at 0% or 100%. However, DPharp can be adjusted in any range with full boost/full suppression. As long as the transmitter is programmed in the correct range, all necessary things in the process (usually provided by the sight glass) are only known. The output can be adjusted in any of the following two ways.
1. Simply adjust the encoder on DPharp until the output reaches a known point. In Figure 1, the output is adjusted to 60%.
2. The correct value can be input to J10:Zero Adj. In this example, the correct output value will be entered - 60%. The value of the deviation can also be viewed in J11:Zero Dev.
DPharp's digital sensing technology makes it possible. With analog sensing technology (such as capacitive sensors), changing the range usually requires recalibration or A/D converter reduction in order to achieve the specified performance. The digital DPharp sensor does not have an A/D converter, so there is no need to cut it. The new range of performance can be guaranteed within the specified range.
note
1. It is important to maintain a stable reference pressure in the liquid level measurement. In a closed container system, the use of a remote seal and capillary system is most helpful in achieving this.
2. It is important to note that the range calculation is based on the process height X specific gravity of the process fluid and does not need to match the physical height.
3. The output will have a linear relationship with the level, regardless of whether it is a liquid or a filtration system.
4. The use of a remote seal eliminates many problems such as condensation in the pulse piping, maintenance requirements of the condensate container, and leakage of the fill fluid during the process.