What are the interference measures for pressure sensors

What are the interference measures for pressure sensors
Pressure sensor is the most commonly used sensor in industrial practice. It is widely used in various industrial automation environments, including water conservancy and hydropower, railway transportation, intelligent buildings, production automation, aerospace, military, petrochemical, oil well, electric power, ships, machine tools , Pipelines and many other industries, so the daily use and maintenance are particularly important. The following editor will introduce you in detail.
Inevitable error of pressure sensor
When choosing a pressure sensor, we have to consider its comprehensive accuracy. What are the influences on the accuracy of the pressure sensor? In fact, there are many factors that cause sensor errors. Below we pay attention to four unavoidable errors, which are the sensor’s Initial error.
Offset error:
Since the vertical offset of the pressure sensor remains constant throughout the pressure range, changes in transducer diffusion and laser adjustment and correction will produce offset errors.
Sensitivity error:
The size of the error produced is proportional to the pressure. If the sensitivity of the device is higher than the typical value, the sensitivity error will be an increasing function of pressure. If the sensitivity is lower than the typical value, then the sensitivity error will be a decreasing function of pressure. The cause of this error is the change in the diffusion process.
Linearity error:
This is a factor that has a small effect on the initial error of the pressure sensor. The cause of the error is the physical nonlinearity of the silicon chip, but for the sensor with an amplifier, the nonlinearity of the amplifier should also be included. The linear error curve can be a concave curve or a convex curve load cell.
Lag error:
In most cases, the hysteresis error of the pressure sensor is completely negligible, because the silicon chip has a high mechanical stiffness. Generally, only the hysteresis error needs to be considered when the pressure changes greatly.
The four errors of the pressure sensor are unavoidable. We can only choose high-precision production equipment, use high-tech to reduce these errors, and can also perform a little error calibration when leaving the factory to reduce the error as much as possible. Meet the needs of customers.
Anti-interference measures for pressure sensors
Maintain stability
Most sensors will "drift" after overtime work, so it is necessary to understand the stability of the sensor before buying. This kind of pre-work can reduce the troubles that will occur in future use.
Pressure sensor packaging
The packaging of the sensor, in particular, is often easy to overlook its frame, but this will gradually expose its shortcomings in future use. When purchasing a transmitter, you must consider the working environment of the sensor in the future, how the humidity is, how to install the sensor, and whether there will be strong impact or vibration.
Select output signal pressure
What kind of output signal the sensor needs: mV, V, mA and frequency output digital output depends on many factors, including the distance between the sensor and the system controller or display, whether there is "noise" or other electronic interference signals. Do you need an amplifier, the location of the amplifier, etc. For many OEM devices where the distance between the sensor and the controller is short, the sensor with mA output is the most economical and effective solution. If the output signal needs to be amplified, it is best to use a sensor with built-in amplification. For long-distance transmission or strong electronic interference signals, it is best to use mA-level output or frequency output.
If you are in an environment with high RFI or EMI indicators, in addition to choosing mA or frequency output, you must also consider special protection or filters. (Currently due to various acquisition needs, there are many types of pressure sensor output signals on the market, mainly 4-20mA, 0-20mA, 0-10V, 0-5V, etc., but the more commonly used ones are 4-20mA and There are two types of 0-10V. Among the output signals I mentioned above, only 2-20mA is a two-wire system. The output we said is a few-wire system without grounding or shielding wires. The others are three-wire systems).
Select excitation voltage
The type of output signal determines what excitation voltage is selected. Many amplified sensors have built-in voltage regulators, so their power supply voltage range is relatively large. Some transmitters are configured quantitatively and need a stable working voltage. Therefore, the available working voltage determines whether to use a sensor with a regulator. When choosing a transmitter, the working voltage and system cost must be considered comprehensively.
Do you need interchangeable sensors
Determine whether the required sensors can accommodate multiple use systems. Generally speaking, this is very important. Especially for OEM products. Once the product is delivered to the customer, the cost for the customer to calibrate is considerable. If the product has good interchangeability, even if the sensor used is changed, the effect of the entire system will not be affected.
other
After we determine some of the above parameters, we must confirm the process connection interface of your pressure sensor and the power supply voltage of the pressure sensor; if it is used in special occasions, also consider the explosion-proof and protection level.
Daily use and maintenance of pressure sensor
Prevent dregs from depositing in the pipe and the sensor from contact with corrosive or overheated media.
When measuring gas pressure, the pressure tap should be opened at the top of the process pipeline, and the sensor should also be installed on the upper part of the process pipeline so that the accumulated liquid can be easily injected into the process pipeline.
When measuring the liquid pressure, the pressure tap should be opened on the side of the process pipeline to avoid slag deposits.
The pressure guiding tube should be installed in a place with small temperature fluctuations.
When measuring the liquid pressure, the installation position of the sensor should avoid the impact of the liquid (water hammer phenomenon) to avoid damage to the sensor due to overpressure.
When freezing occurs in winter, the sensor installed outdoors must take anti-freezing measures to prevent the liquid in the pressure inlet from expanding due to icing and causing sensor loss.
When wiring, pass the cable through the waterproof connector or flexible tube and tighten the sealing nut to prevent rainwater from leaking into the transmitter housing through the cable.
When measuring steam or other high-temperature media, a condenser such as a buffer tube (coil) should be connected, and the working temperature of the sensor should not exceed the limit.