In the field of chemical engineering applications, pressure transmitters play a crucial role and are widely used. There are various types of pressure transmitters, which can be divided into three categories based on the measurement object: pressure transmitters, gauge pressure transmitters, and differential pressure transmitters. Depending on different environmental conditions, application scenarios, installation conditions, and other factors, there are varying requirements for the selection of transmitters.    

Type selection of transmitters in the field of pressure measurement

In the field of pressure measurement, pressure transmitters are predominantly used in the forms of medium and low gauge pressure transmitters, medium and high gauge pressure transmitters, and single flange diaphragm sealed pressure transmitters for medium and low gauge pressures. According to different installation methods for measurement, transmitters can be further categorized into two types: direct pipeline connection installation and pressure tapping installation via a pressure conduit. In the case of micro-pressure conditions, direct pressure measurement may lead to unstable fluctuations. Therefore, when measuring micro-pressures not exceeding 500Pa, it is more reasonable to choose a differential pressure transmitter.   

In the field of differential pressure and liquid level measurement, the selection of transmitter types involves the so-called differential pressure measurement, which refers to obtaining the pressure difference value by subtracting pressures measured using a transmitter. In the field of liquid level measurement, measurement results can be obtained through differential pressure measurement methods. Transmitters that can be used in the field of liquid level measurement include differential pressure transmitters, high differential pressure transmitters, flange-mounted differential pressure transmitters, and diaphragm-sealed double flange differential pressure transmitters. When measuring the liquid level of an atmospheric pressure vessel, it is advisable to use a pressure transmitter or a single flange diaphragm-sealed pressure transmitter due to the vessel being connected to the atmosphere. When measuring the liquid level pressure of a sealed vessel, there may be gas phase volatilization in the vessel's negative pressure chamber, or the lower end of the vessel may be nitrogen-sealed. Therefore, when measuring the hydraulic pressure, if a flange-mounted transmitter is selected, the negative pressure chamber needs to be connected via a pressure guiding tube. If a diaphragm-sealed transmitter is chosen, both the positive and negative pressure chambers must be connected using remote flanges. For open pools, if there is silt at the bottom, a single flange sealed diaphragm pressure transmitter can be selected to measure the liquid level.   

Selection of transmitter types in the field of flow measurement: Flow measurement generally involves the selection of differential pressure transmitters and diaphragm-sealed double-flange differential pressure transmitters. Differential pressure transmitters require the combination of throttling devices such as orifice plates, Annubar, and Venturi tubes, and the measured result is also a differential pressure value. If measuring media such as steam or gas, it is also necessary to obtain the flow rate value through corresponding calculations performed by a secondary meter or a supervisory system such as DCS/PLC.   

Of course, pressure transmitters are widely used in the chemical industry. When selecting a pressure transmitter, it is necessary to specifically consider the chemical characteristics of the application environment, taking into account comprehensive factors such as temperature, concentration, and corrosivity. Then, by weighing its economic efficiency, a reasonable type of pressure transmitter should be chosen to better meet the needs of chemical production activities.