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1. Precautions for measuring differential pressure with double flange transmitters (differential pressure range: 0–50 KPa). When the double flange transmitter is installed without any process connection, it is necessary to set the current PV value to zero in order to ensure that the differential pressure value, the output current value, and the instrument’s measurement range remain consistent. The differential pressure range is 0---50 KPa, and the zero point of the instrument does not shift when measuring differential pressure. If a dual-flange transmitter cannot be zeroed using HART 475, the transmitter’s built-in mechanical zero button should be used for zeroing. The double-flange capillary must be securely fixed. It is also possible to install two pressure gauges and perform subtraction in the system logic. Second, precautions for measuring flow rate using double-flange transmitters (differential pressure range: 0–50 KPa). When the double flanges are installed without any load, it is necessary to set the current PV value to zero in order to ensure that the differential pressure value, the output current value, and the instrument’s measurement range remain consistent. The differential pressure range is 0---50 KPa, and the instrument’s zero point does not shift when measuring flow rate. Since the square of the flow rate is proportional to the pressure difference, migration is not allowed when measuring the flow rate. If a dual-flange transmitter cannot be zeroed using HART 475, the transmitter’s built-in mechanical zero button should be used for zeroing. The double-flange capillary must be securely fixed. Third, precautions for measuring liquid level using double flange transmitters (differential pressure range: 0–50 KPa). When the double flange transmitter is installed with no liquid present, the current PV value should be set to the lower range limit LRV of the instrument. To measure the liquid level, a negative offset is required; the magnitude of this offset is equal to P (silicone oil density) × GH, and the lower range limit LRV is equal to –P (silicone oil density) × GH