How to choose Fuji FKE single flange liquid level transmitter and FKD, FKX double flange differential pressure transmitter?
Fuji FKE Single Flange Level Transmitter
Fuji FKE single-flange liquid level transmitter means that the positive pressure side of the pressure transmitter is a flange structure, which is directly connected to the interface of the measuring medium, while the negative pressure side uses a pressure pipe to connect the measuring medium and the transmitter. The chambers are connected.
The advantage is that the measurement accuracy is high and can reach the measurement technical indicators of the transmitter. The disadvantage is that the negative pressure pipeline must be absolutely sealed, and the transmitter needs to be ranged. During calibration, the error of the medium liquid in the negative pressure pipeline should be migrated. Lose.
The Fuji FKE single-flange liquid level gauge measures the liquid level of the open tank. The following factors are mainly considered when selecting the type:
1. Measurement objects, such as the physical and chemical properties of the measured medium, as well as the working pressure and temperature, installation conditions, the speed of liquid level change, etc.;
2. Measurement and control requirements, such as measurement range, measurement accuracy, display mode, on-site indication, remote indication, interface with computer, safety and corrosion resistance, reliability and convenience of construction.
Fuji FKD, FKX double flange differential pressure transmitter
Double flange differential pressure transmitter means that the positive and negative pressure sides of the pressure transmitter are flanged structures, which are used to prevent the medium in the pipeline from directly entering the pressure sensor assembly in the transmitter. The devices are connected by fluid-filled capillaries. It is used to measure the liquid level, flow rate and pressure of liquid, gas or steam, and then convert it into 4~20mA DC signal output.
The advantages are easy installation, convenient calibration, and no need for range migration. The disadvantage is that the measurement accuracy is not high. Due to the elastic hose connection between the flange and the transmitter, the interior should be filled with silicone oil, so there is a certain deviation in the transmission of medium pressure changes, and the external temperature change is somewhat affected by silicone oil. Therefore, there is a certain error in the measurement reflection.
FKD, FKX double flange differential pressure transmitter consists of two flanges, mainly used in closed equipment kettle tank to measure liquid level, suitable for high temperature and high pressure, strong corrosion and other media.
1 Selection considerations
(1) Determine the model of the pressure transmitter
The model determination of the pressure transmitter refers to the model confirmation of the measuring head. The confirmation process needs to be based on the measurement pressure range, output mode (4~20mA with HART protocol or Profibus, etc.), process flange type, capillary connection form, Whether it has parameters such as LCD head for model selection. The choice of whether to use a liquid crystal head depends on the ambient temperature of the transmitter. If the ambient temperature is too low (below minus 25), it is not recommended to bring a liquid crystal head, because according to the actual application experience on site, if the ambient temperature is too low, the liquid crystal The display will not show.
(2) Determine the Diaphragm Seal Assembly Model
Diaphragm seal assembly model confirmation refers to the model confirmation of flange and capillary. During the confirmation process, model selection should be made according to parameters such as diaphragm seal type, seal position, capillary filling liquid, and capillary connection length. Among them, the capillary filling liquid should be selected according to the temperature of the measuring medium. If the filling liquid is not selected properly, it may cause the double flange differential pressure transmitter to be unable to adapt to the temperature of the measuring medium during use, resulting in the inability of the instrument to measure normally and accurately.
Summarizing the above two types of transmitters, Fuji FKE single flange is used to measure the liquid level of open tanks, and FKD and FKX double flanges are used to measure the liquid level of closed tanks.
