1. What kind of pressure does the sensor measure?
Answer: The first thing to consider is the maximum pressure of your system. The maximum pressure range of the pressure sensor usually required should reach 1.5 times the maximum pressure value of the system. The reason for this proposal is that these additional pressure ranges are due to pressure spikes or continuous pulses in many systems (especially water pressure and process control). These spikes can reach five times the "maximum" pressure, or even ten times, and can cause damage to the sensor. Continuous high-pressure pulses, approaching or exceeding the maximum rated pressure of the sensor, will shorten the life of the sensor. When selecting a sensor, simply increasing the rated pressure of the sensor is not a panacea, because the resolution of the sensor will be sacrificed. The best compromise is to choose to use a buffer to attenuate the spikes, even this will somewhat reduce the response speed of the sensor.
2. What is a pressure medium?
Answer: Another key factor to consider when selecting a sensor is the medium being measured. Will there be a viscous liquid or paste on the pressure contact surface? Is the contact with the sensor a soluble or corrosive medium or clean and dry air?
3. What accuracy does the sensor need to achieve?
Answer: Accuracy is usually a term commonly used for sensor output error. These errors may come from non-linearity, hysteresis, non-repeatability, temperature, zero balance, correction and humidity effects. For many sensors, the "accuracy" will be lower than the nominal value due to factors such as temperature and zero balance.
The cost of having a higher accuracy sensor will be higher, so does your system really need such a high degree of accuracy? A system composed of high-precision sensors and low-resolution instruments is actually an inefficient solution.
4. What is the temperature resistance of the sensor?
Answer: Pressure sensors, like all physical equipment systems, will cause errors and even become unusable under extreme temperature environments. Generally, each sensor will have two temperature ranges, which are the working range and the compensation range. The compensation range is included in the working range.
The working range means that within this range, the sensor can be exposed to the medium without being damaged after being energized. However, this does not mean that its performance can reach the nominal specifications (temperature coefficient) when it is outside the compensation range.
The compensation range is generally a narrower range within the working range. Within this range, the sensor ensures that the nominal specifications can be reached. The temperature change affects the sensor in two ways, one is to cause zero drift, and the other is to affect the output of the entire range. The sensor specification should list these errors in the following form: ±x% full scale/°C, ±x% reading/°C, ±x% full range within the entire temperature compensation range, or ±x% within the entire temperature compensation range reading. Without these parameters, it will cause uncertainty in your use. So is the change in sensor output due to pressure change or temperature change? When understanding how to use a sensor, the temperature effect will be the most complicated part.
5. What kind of output should be used?
Answer: Almost all sensors have millivolt output, or voltage amplification, or milliamp, or frequency output. The output type you choose depends on the distance between your sensor and system control or display components, noise, and other electrical interference, as well as whether it needs to be amplified, and the best location for the amplifier. For many original equipment manufacturers, the distance between their control components and sensors is very short, so millivolt output is generally sufficient and the cost is low.
If you need to amplify the sensor output, it is easier to use another sensor with a built-in amplifier. In long-distance cables, or in areas with large electrical noise, mA output or frequency output is required. In an environment with strong radio frequency interference and electromagnetic interference, you need to consider adding some additional shielding or filtering equipment to the mA and frequency output.
6. What is the excitation voltage?
Answer: The type of output may determine the excitation voltage you need. Many amplified sensors have built-in voltage regulators that can work with a wide range of unregulated voltage sources. Some sensors are proportional and require a regulated excitation source. The power source used will determine whether you are using a regulated or unregulated power source. This requires a compromise between system cost and all incentive sources.
7. Do I need the sensors to be interchangeable?
Answer: Is the interchangeability of sensors important for different systems, or will you calibrate every part of the system? This is a very important issue, especially for original equipment manufacturers. After you deliver the product to the customer, the cost of calibration is very high. If your sensors are interchangeable, then you can replace the sensors in the system and still keep the parameters unchanged.
8. What degree of time stability does the sensor need?
Answer: Most sensors will "drift" over time. It is very important to understand the stability of the sensor over time. This preliminary work requirement can reduce the problems that may be encountered in the future.
9. How sturdy is the sensor?
Answer: A factor that makes users a headache is often encountered, that is, what mechanical strength does the sensor need, especially its housing? It is very important to consider the environment in which the sensor will be applied. Is it in a high humidity or water vapor environment? Is there high-intensity vibration or shock? These issues must be considered carefully when choosing a housing type.
10. How do I connect the sensor to my electrical system?
Answer: Is the short cable on the sensor enough? Or, in long cable applications, is it necessary to add a connector to the sensor? Most pressure sensors can provide cables or connectors.
