Precautions for the installation and measurement applications of differential pressure transmitters

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Differential pressure transmitters are used to measure the level, density, and pressure of liquids, gases, and vapors, and then convert these values into a current signal of 4-20 mADC for output; the differential pressure value can be displayed using a gauge. A differential pressure transmitter for measuring differential pressure values; this transmitter is robust and resistant to vibration, and its range, zero point, and damping can be adjusted continuously on-site. It features high performance and good stability. Combining different sensor technologies with a compact aluminum alloy or plastic housing, differential pressure transmitters can be used for measuring a variety of liquids and gases. The differential pressure transmitter utilizes a fully sealed oil-filled isolation technology, along with a unique dual-core design, which provides reliable protection against static pressure and significantly enhances its resistance to reverse overload. Intelligent compensation technology ensures stable performance over the long term, allowing it to be used effectively in a wide range of precision measurements, including those related to the flow of gases and liquids. Differential pressure transmitters differ from ordinary pressure transmitters in that they have two pressure interfaces; they are typically divided into a positive pressure side and a negative pressure side. In general, the pressure on the positive pressure side of a differential pressure transmitter must be higher than that on the negative pressure side in order to carry out measurements. Installation requirements for differential pressure transmitters: 1. The installation location of the differential pressure transmitter on the process pipeline is determined by the medium being measured. To achieve optimal installation results, it is necessary to take into account the following factors: preventing direct contact between the transmitter and corrosive or excessively hot media ； Prevent residue from accumulating in the pressure guiding pipe and causing blockages ； The lengths of the pressure tapping pipes on the positive and negative pressure sides should be as similar as possible ； The hydrostatic head of the liquid columns in the pressure tapping pipes on the positive and negative pressure sides should be kept balanced; these pressure tapping pipes are installed in areas with temperature gradients and temperature fluctuations ； 2. When measuring liquid flow rate, the differential pressure transmitter should be installed beside or below the pipeline being measured, so that bubbles can be discharged into the pipe ； 　　 3. When measuring gas flow rate, the differential pressure transmitter should be installed beside or above the pipeline being measured, so that any accumulated liquid can easily flow into the pipeline ； 　　 4. When measuring steam flow, the differential pressure transmitter should be installed below the pipeline being measured, so that condensate can fill the pressure guiding tubes. It should be given special attention that when measuring steam or other high-temperature media, it is necessary to prevent the temperature of the medium in contact with the differential pressure transmitter from exceeding the maximum operating temperature allowed for the transmitter. 　　 Points to note for differential pressure transmitters: (1) During design and installation, it should be considered to place the pressure-taking openings at the bottom of the oil tank as low as possible in order to eliminate errors caused by temperature changes; temperature compensation should be employed if necessary. 　　 (2) When the horizontal cross-section of the oil tank is not uniform (e.g., smaller at the top and larger at the bottom), compensation measures need to be considered. For secondary meters, the WP-H80 series level-volume controller is selected. 　　 (3) To achieve a certain requirement, such as when a breather valve is installed on the top of an oil tank, a differential pressure transmitter must be used instead of a pressure transmitter. For open-top oil tanks or in cases where high requirements are not necessary, pressure transmitters can be used directly to facilitate installation. 　　 (4) Where possible, use smart meters for secondary instruments, as they facilitate range adjustment and enable temperature compensation, among other functions.