DP capillary transmitter

DP capillary transmitter

Capillary DP transmitters allow the transmitter to separate from direct contact with the process fluid

Capillary DP transmitters are useful to

1- The process temperature is outside the normal range of the transmitter operation and it cannot be entered by piping

۲. The process is corrosive and requires frequent transmitter replacement

3. This process requires unusual constructions

4- This process contains a lot of solids or is viscous. Both conditions can connect the impact pipes

5- The program needs to use sanitary fittings

6. To prevent contamination between the handles, there is a need for easy process cleaning of the joints

7. Wet feet need to be replaced to reduce maintenance In cases where wet feet are not stable or often need to be refilled

 The basic surface measurement uses the same principle as the DP capillary transmitter: the pressure is proportional to the surface. The pressure of the liquid head is proportional to its height, which is multiplied by its specific gravity. Careful selection of remote seals is crucial in maintaining a reasonable performance expectation from the pressure transmitter

An open tank, a single-diaphragm flood system, with a transmitter under the valve, is very similar to a transmitter system that uses shock tubes that use a process fluid-filled transmitter. The difference is that the distance between the valve and the transmitter must be calculated instead of the process fluid with the specific gravity (S) of the filled liquid. Note this is the vertical distance, not the capillary length

Flood apertures have another advantage over the parts that are directly connected to the flood, there is more installation capability to install the transmitter. The transmitter can be placed on top of the valve. This is especially useful when burying the tank or when the transmitter should be in a more comfortable area. The transmitter can be mounted on top of the valve as long as the back pressure on the seal does not exceed 1 pressure (33.9 ft). When the seal is higher than the valve, the level calculation is slightly different because the distance must be reduced from the surface instead of the added one

In closed systems, the location of the transmitter is limited by the maximum allowable distance above the lower faucet. In pressurized systems, this is the equivalent of 1 atmosphere previously seen. In sub-atmosphere systems (vacuum systems) the transmitter must be installed at the valve or at the bottom of the valve. This ensures that the transmitter always sees positive pressure on both the measuring and reference sides. In two sealing systems, the distance between the taps is converted from zero to reference compensation. The calculations are the same regardless of where the transmitter is installed

Capillary DP Transmitter Applications

Using a DP capillary transmitter increases the number of applications that can use a pressure transmitter. However, the entire sealing assembly, diaphragm seals, capillaries and filled fluids must be selected and installed to optimize performance

The use of remote flood diaphragms has several advantages over wet foot systems

• The diaphragm of remote seals allows fluids to be maintained between the valve and the transmitter, especially at the reference point (low pressure)

• In vacuum systems, a closed sealing system maintains a constant degree of downward reference, rather than a wet foot

Because the diaphragm of remote seals is a pressure transmitter format, the accuracy of the transmitter measurement is the same. However, using remote seals can add an error to the overall performance of the system. Changes in temperature and the installation of the transmitter are important parameters that must be considered.

Temperature effects