The Importance of Calibrating Diffused Silicon Pressure Transmitters

As a core component in industrial automation control，the measurement accuracy of diffused silicon pressure transmitters directly affects production safety and efficiency。Models such as YMP-YMP489 convert pressure signals through the piezoresistive effect of semiconductor strain gauges，but long-term use or environmental changes can cause zero-point and span drift。According to statistics，the error of transmitters that are not calibrated regularly can reach up to 2.5% of full scale，which may cause serious consequences for processes requiring precise control（such as pressure monitoring of chemical reaction kettles）。

Taking the YM-1XH pressure transmitter as an example，its manual clearly requires recalibration every 6 months or when operating conditions change abruptly。The calibration process is essentially to establish a linear relationship between the sensor output（4-20mA or 0-10V）and the actual pressure through a standard pressure source。It is worth noting that，Domestic Instrument SWP-D803 Temperature Detection Alarm Digital Display Control Instrument Controller and other high-precision instruments can be used as auxiliary equipment to monitor signal stability in real time during the calibration process。

Preparation Before Calibration

1. Equipment Inspection：Confirm the power supply voltage（24VDC ±10%）and output signal type of the YMP-YMP489 pressure transmitter（for example，the DMK331-250-4000 model supports the HART protocol）。Check whether the sensor diaphragm is clean，especially after measuring corrosive media，it should be rinsed with deionized water

2. Selection of Standard Instruments：According to the accuracy class of the YD-322 pressure transmitter（usually class 0.1 or 0.2），select a piston pressure gauge or digital pressure controller with accuracy 3 times higher than that of the instrument under test。For example，for a YM-115 transmitter with a range of 0-1MPa，the standard instrument must have an accuracy of 0.03%FS or better

3. Environmental Control：The laboratory temperature should be stable at 23±2℃，and the humidity should be ≤60%RH。For on-site calibration，vibration and electromagnetic interference must be avoided（for example，keep more than 3 meters away from frequency converters）

Detailed Explanation of the Three-Step Calibration Method

Step 1：Zero Calibration

Disconnect the pressure connection pipe and ensure that the YMP-YMP489 is under atmospheric pressure。Use a handheld terminal or SWP-D803 digital display instrument to read the current output value，which should ideally be 4mA（current output）or 0V（voltage output）。If the deviation exceeds the allowable value（such as ±0.05mA specified in the YM-130 specification），adjust it through the transmitter zero-adjustment screw or enter the "ZERO" command with a HART handheld communicator。Note：Diffused silicon sensors are sensitive to temperature，so confirmation should be made after waiting 5 minutes for thermal equilibrium

Step 2：Full-Scale Calibration

Connect the standard pressure source and apply the rated pressure（such as the 10MPa full scale of MBS-G3131）。Slowly increase the pressure to 95%FS and hold it for 1 minute，then observe whether the output reaches 20mA。If there is a deviation，calculate the adjustment coefficient according to the following formula：
K=(P_standard-P_display)/(P_display×100%)
Enter the correction value through the span potentiometer or digital menu，repeat 3 times and take the average value。This step is particularly critical for transmitters used in trade settlement，such as YSZK-01G-C

Step 3：Linearity Verification

Conduct forward and reverse stroke tests at 25%FS interval points（0%，25%，50%，75%，100%），and record the output characteristic curve of the YM-1QQ transmitter。The allowable nonlinearity error should be less than the value marked in the specification（such as 0.2%FS for YD-322）。If excessive hysteresis is found，it may be due to plastic deformation of the silicon diaphragm caused by sensor overload，and the manufacturer should be contacted for inspection and repair

Professional tip：After calibration is completed，apply anti-rust silicone grease to the process connection threads，and attach a traceability label containing the calibration date，personnel，and standard instrument number

Solutions to Common Problems

Recommended Calibration Tools and Summary

For users without professional calibration equipment，Domestic Instrument SWP-D803 Temperature Detection Alarm Digital Display Control Instrument Controller can be used for simple verification。This device supports fast sampling of 0.2 seconds，with a basic error of less than 0.5%FS，and can accurately capture instantaneous changes in the transmitter output signal。Its dual alarm function can also be set to provide calibration out-of-tolerance reminders，greatly improving work efficiency

Through the above three-step calibration method，diffused silicon pressure transmitters such as YMP-YMP489 can be ensured to continuously provide accurate measurement data。Xi'an Shenghongchuang Instrument Co., Ltd. recommends preventive maintenance every 12 months and keeping complete calibration records。If you need the complete technical manuals for models such as YM-1XH，or want to consult the price details of the YSZK-01G-C pressure transmitter，please feel free to contact our engineering technical team for professional support