According to the technical and sales staff of Jinhu Dongxiang Instrument Co., Ltd. for many years of experience in the production and sales of pressure transmitters ! Provide a pressure transmitter selection advice for customers who need to purchase!
First, the pressure transmitter In order to choose the right equipment, the first principle is that the measurement object is the measurement medium.
1) Based on the property index of the tested medium, it is a reference to save money and facilitate installation and maintenance. 晶、强腐蚀的，必须选用隔离型变送器。 If the measured medium is of high viscosity, easy to crystallize , and strong corrosion, an isolated transmitter must be selected. The isolated pressure transmitter is best to use the screw connection, the investment cost is not high, and the installation is more convenient.
)如果需要采用普通的压力变送器或压力变送器，则介质度可以不予考虑，因为普通型是引压到表内，长期工作时温度是常温，但是还是要考虑下介质的腐蚀性问题。 2 ) If an ordinary pressure transmitter or pressure transmitter is needed, the medium degree can be disregarded, because the ordinary type is induced into the meter, and the temperature is normal temperature during long-term work, but the corrosion of the medium must be considered. Sexual issues.
)还要考虑被测介质对膜盒金属的腐蚀，一定要选好膜盒材质，否则使用后很短时间就会将外膜片腐蚀坏，法兰也会被腐蚀坏造成设备或人身事故，所以膜盒材质的选择非常关键。 3 ) It is also necessary to consider the corrosion of the metal of the capsule by the measured medium. Be sure to choose the material of the capsule, otherwise the outer diaphragm will be corroded within a short time after use, and the flange will be corroded and cause equipment or personal accidents. Therefore, the selection of the material of the capsule is very critical. 304 不锈钢、 316/ 316L 不锈钢、钽材质等。 The transmitter's capsule is made of 304 stainless steel, 316 / 316L stainless steel, tantalum, etc.
Considering the working pressure level of the device, the pressure level of the transmitter must be compatible with the application.
)从经济角度上讲，外膜盒及插入部分材质比较重要，要选用合适的，但连接法兰可以降低材质要求，因为这样可以降低成本。 1 ) From an economic point of view, the material of the outer membrane box and the insertion part is more important. It is necessary to choose a suitable one, but the connection flange can reduce the material requirements because it can reduce costs.
)从使用角度上讲，系统量程的最大值1.5倍比较适合选用。 2 ) From the perspective of use, 1.5 times the maximum value of the system range is more suitable for selection.
)从选用变送器测量范围上来说，一般变送器都具有一定的量程可调范围，最好将使用的量程范围设定在它量程的1/4~3/4段，这样精度会有所保证，对于微差压变送器来说更是重要。 3 ) From the perspective of the measurement range of the selected transmitter, generally the transmitter has a certain range of adjustable range. It is best to set the range of use to 1/4 to 3/4 of its range, so that the accuracy will be Certainty is even more important for micro differential pressure transmitters . 液位测量)需要对变送器的测量范围迁移，根据现场安装位置计算出测量范围和迁移量进行迁移，迁移有正迁移和负迁移之分 In some applications ( level measurement ) , the measurement range of the transmitter needs to be migrated. The measurement range and the migration amount are calculated according to the installation position on the site. The migration has positive and negative migration.
Usually a transmitter will calibrate two temperature sections, one of which is the normal working temperature and the other is the temperature compensation range. The normal working temperature range refers to the temperature range when the transmitter is not damaged in the working state. When the temperature compensation range is exceeded, the performance index of its application may not be achieved.
The temperature compensation range is a typical range smaller than the operating temperature range. Within this range, the working transmitter will certainly reach its due performance index. Temperature change affects its output from two aspects, one is zero drift, and the other is the full-scale output. +/-X%/ ℃，读数的 +/-X%/ ℃，在超出温度范围时满量程的 +/-X% ，在温度补偿范围内时读数的 +/-X% ，如果没有这些参数，会导至在使用中的不确定性。 For example: +/- X% / ℃ of full scale, +/- X% / ℃ of reading, +/- X% of full scale when the temperature range is exceeded, +/- X% of reading when it is within the temperature compensation range Without these parameters, it will lead to uncertainty in use. The change in transmitter output to degree is caused by a change in pressure or a change in temperature. Temperature effects are the most complicated part of understanding how to use a transmitter.
The factors that determine the accuracy level are non-repeatability, temperature, non-linearity, hysteresis, zero offset scale, and temperature effects. But mainly by non-linearity, hysteresis, non-repeatability, the higher the accuracy, the higher the price.
、 mV 、 V及频率输出数字输出，选择怎样 的输出取决于多种因素，包括是否存在“噪声”或其他电子干扰信号，变送器与系统控制器或显示器间的距离，是否需要放大器，放大器的位置等。 General mA , mV , V and frequency output digital output. The choice of output depends on many factors, including whether there is "noise" or other electronic interference signals, the distance between the transmitter and the system controller or display, and whether an amplifier is required. , The location of the amplifier, etc. OEM 设备采用 mA 输出的变送器最为经济而有效的解决方法。 For many OEM devices with a short distance between the transmitter and the controller, the transmitter with the mA output is the most economical and effective solution.
The type of output signal determines what excitation voltage is selected. Many transmitters have built-in voltage regulators, so their supply voltage range is large. Some transmitters have a quantitative 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.
、是否需要具备互换性的变送器 7. Do you need an interchangeable transmitter?
Determine if the required transmitter can accommodate multiple use systems. OEM 产品。 This is generally important, especially for OEM products. Once the product is delivered to the customer, the cost of the customer's calibration is considerable. If the products have good interchangeability, then even the change of the transmitter used will not affect the effect of the entire system.
、 变送器超时工作后需要保持稳定度 Eight , the transmitter needs to maintain stability after overtime work
Most transmitters will "drift" after excess work, so it is necessary to understand the stability of the transmitter before purchasing. This kind of pre-work can reduce all kinds of troubles in future use.
Nine , what kind of connection is used between the transmitter and other electronic equipment?
Do you need a short-range connection? Do I need a connector for long distance connections?
、 变送器的封装 Ten , the package of the transmitter
的封装，往往容易忽略是它的机架，然而这一点在以后使用中会逐渐暴露出其缺点。 The package of the transmitter is often overlooked by its frame, but this will gradually reveal its disadvantages in future use. When choosing a transmitter , you must take into account the working environment of the transmitter, the humidity, how to install the transmitter, and whether there will be strong impact or vibration.