1. Measurement Range First, determine the maximum pressure to be measured in the system. Generally, a transmitter with a pressure range approximately 1.5 times larger than the maximum value should be selected. This is mainly because many systems, especially in water pressure measurement and processing, experience peak values ​​and continuous irregular fluctuations. These instantaneous peaks can damage pressure sensors. Sustained high pressure values ​​or slightly exceeding the transmitter's calibrated maximum value will shorten the sensor's lifespan and decrease accuracy. A buffer can be used to reduce pressure spikes, but this will reduce the sensor's response speed. Therefore , pressure range, accuracy, and stability must be fully considered when selecting a transmitter. 2. Measurement Medium Viscous liquids and slurries can clog pressure ports. Solvents or corrosive substances may damage the materials in the transmitter that come into direct contact with these media. These factors will determine whether to select a direct isolation diaphragm and the materials that come into direct contact with the media. 3. Accuracy Class Factors determining accuracy include nonlinearity, hysteresis, non-repeatability, temperature, zero-point offset calibration, and the effect of temperature. However, due to its nonlinearity, hysteresis, and non-repeatability, the higher the accuracy, the higher the price. 4. Temperature Range A transmitter is typically calibrated with two temperature ranges: one is the normal operating temperature, and the other is the temperature compensation range. The normal operating temperature range refers to the temperature range within which the transmitter can operate without damage. Outside the temperature compensation range, the transmitter may not meet its performance specifications. The temperature compensation range is a typical range smaller than the operating temperature range. Within this range, the transmitter will definitely achieve its expected performance specifications. Temperature affects the output in two ways: zero-point drift and full-scale output. For example, the full-scale output is +/-X%/℃, and the reading is +/-X%/℃. Outside the temperature range, the full-scale output is +/-X%, and within the temperature compensation range, the reading is +/-X%. Without these parameters, uncertainty in use will result. It's crucial to determine whether the change in transmitter output is caused by pressure or temperature changes. Understanding temperature effects is one of the most complex aspects of understanding how to use a transmitter. 5. Output Signal (mV, V, mA) and Frequency Output: The choice of output type depends on various factors, including the distance between the transmitter and the system controller or display, the presence of noise or other electronic interference signals, whether an amplifier is needed, and the amplifier's location. For many OEM devices with short distances between the transmitter and controller, mA output transmitters are the most economical and effective solution. If amplification of the output signal is required, it is best to use a transmitter with built-in amplification. For long-distance transmission or in the presence of strong electronic interference signals, mA-level output or frequency output is preferable. In environments with high RFI or EMI requirements, in addition to choosing mA or frequency output, special protection or filters should also be considered. 6. Selection of Excitation Voltage: The type of output signal determines the selection of excitation voltage. Many transmitters have built-in voltage regulators, thus offering a wide power supply voltage range. Some transmitters are fixed-configuration and require a stable operating voltage. Therefore, the operating voltage determines whether a sensor with a regulator is used. When selecting a transmitter, the operating voltage and system cost must be considered comprehensively. 7. Is an Interchangeable Transmitter Required? Determine if the required transmitter can be adapted to multiple systems. This is generally important, especially for OEM products. Once the product is delivered to the customer, the calibration costs can be substantial. Good interchangeability means that changing the transmitter used will not affect the overall system performance. 8. Transmitter Stability After Overtime Operation Most transmitters experience "drift" after overtime operation. Therefore, it's essential to understand the transmitter's stability before purchase. This proactive approach reduces future problems. 9. Transmitter Packaging The transmitter's packaging, often overlooked, is its frame. However, its shortcomings will become apparent during use. When selecting a transmitter, consider its future operating environment: humidity levels, installation method, and potential exposure to strong impacts or vibrations.