The selection of pressure transmitter is mainly based on the type of measured pressure, maximum overload of the system, accuracy grade, measurement range and other angles. After determining the manufacturer and model of the transmitter, determine the range of the transmitter according to the use requirements. The selection of measuring range shall follow the principles of adjustable measuring range up and down, the highest accuracy and suitable price.
There is a given continuous functional relationship (usually linear function) between the output signal of the pressure transmitter and the pressure variable. In order to ensure that the transmitter you choose meets the requirements of field use, there are several points to pay attention to during model selection:
1. Types of measuring pressure: the pressure types mainly include gauge pressure, absolute pressure, differential pressure, etc; Gauge pressure refers to the pressure less than or greater than atmospheric pressure based on atmospheric pressure; Absolute pressure refers to the pressure higher than the zero position of positive pressure based on the zero position of positive pressure; Differential pressure refers to the difference between two pressures.
2. Accuracy grade: the measurement error of the transmitter is divided according to the accuracy grade. In the actual use process, it is selected according to the demand of measurement error and the principle of applicability and economy.
3. Maximum overload of the system: the maximum overload of the system shall be less than the overload maintenance limit of the transmitter, otherwise it will affect the service life of the commodity and even damage the commodity. The overload maintenance of 2 times the measurement scale is the standard equipment of our company's goods (it can also be customized according to the customer's request).
4. The general measuring range is 80% of the actual measuring range.
5. Working temperature scale: the temperature of the measuring medium shall be maintained within the temperature range that the pressure transmitter can work normally. If the temperature exceeds the applicable range, the error will become great and the service life of the instrument will be shortened accordingly; In the production process of pressure transmitter, the temperature influence will be measured and compensated to ensure that the measurement error of goods affected by temperature is within the range of accuracy requirements. When the temperature is high, we can consider selecting high-temperature pressure transmitter or adopting auxiliary cooling methods such as condenser and radiator.
6. Compatibility between measuring medium and touch raw materials: in some application places, because the measuring medium is corrosive, it is necessary to select data compatible with the measuring medium or carry out special process treatment to ensure that the transmitter is not damaged.
7. Pressure interface method: usually the commodity is connected with thread (M20 × 1.5) is the standard interface method.
8. Power supply and output signal: usually 24V power supply, and the output signal includes 4 ~ 20mADC, 0 ~ 5VDC, 1 ~ 5VDC, 0 ~ 10VDC, etc