Pressure Sensor Specifications
In this post, Lets discover the key considerations for selecting pressure sensors and transmitters in various industries as we delve into their general specifications.
Pressure Sensor Specifications
When it comes to measuring pressure in chemical or fluid systems, ensuring balance is crucial to prevent potential damage. The selection of a pressure sensor involves considering various factors to meet specific requirements and ensure accurate measurements. To make the right choice, it’s essential to understand the different aspects of a pressure sensor. Familiarizing ourselves with the general specifications is crucial. In this post, we will delve into the key specifications to consider when selecting a pressure sensor, empowering you to make informed decisions that align with your specific needs.
Pressure Range
The measurement of pressure is indeed a fundamental parameter when selecting a pressure sensor. Pressure is typically sensed and expressed in units such as bar, kg/cm², or psi.
Understanding the required pressure unit is essential in choosing a pressure sensor that can accurately measure and display the pressure readings in the desired unit of measurement.
One important consideration when selecting a pressure sensor is to choose a sensor with a range that is higher than the maximum working range of the medium being measured. It is recommended to select a sensor with a range that provides a comfortable margin above the expected maximum pressure.
For example, if the maximum working range of the medium is anticipated to be 8 psi, it is advisable to select a pressure sensor with a maximum range of 15 psi. This ensures that the sensor can handle the expected pressure without reaching its upper limit, allowing for reliable and accurate measurements.
It is generally recommended to choose a pressure sensor with approximately 50% extra range for safe and reliable pressure measurement in various conditions.
However, it is important to avoid selecting a sensor with an excessively higher rating than required. Opting for a sensor with an excessively high range, such as a 20 psi sensor for an application that only requires 8 psi, can lead to unnecessary costs and potentially compromise accuracy.
Therefore, striking the right balance between having an adequate safety margin and selecting a sensor within the appropriate range is crucial for cost-effectiveness and maintaining accurate pressure measurements.
Please note that pressure ranges are typically classified into two types:
A) working pressure range
B) burst pressure range
The working pressure range refers to the pressure range within which the medium normally operates.
On the other hand, the burst pressure is the maximum pressure that a system or pipe can withstand before it fails or bursts.
Exceeding the burst pressure can result in damage or failure of the system. It is crucial to select a pressure sensor that can safely measure the working pressure range of the medium while ensuring it remains below the burst pressure to avoid any potential risks or damage to the system.
Sensor Output
When using a pressure sensor, it is necessary to have a means of measuring the sensor’s output, typically through a PLC or controller.
The electrical output of the sensor can be classified into two types: Analog and Digital.
Analog output is available in two common options: 4-20 mA or 0-10 V. These analog signals provide continuous variable measurements proportional to the pressure being sensed.
Digital output is usually represented as either Normally Open (NO) or Normally Closed (NC) signals, indicating discrete on/off states. The choice between analog and digital output depends on your specific requirements and budget.
Analog output is always costlier than digital output. Lets take an example !!
A 0-40 psi sensor, can provide a corresponding 4-20 mA output signal that can be scaled to represent the measured pressure accurately.
On the other hand, digital output pressure sensors operate by setting a specific pressure value within the transmitter. Once this pressure is reached, the relay output will switch open or closed based on the predetermined configuration.
In addition to analog and digital outputs, modern pressure sensors may also offer communication-form outputs such as Serial, HART, Profibus, Device Net, Ethernet, or CAN Open. These communication protocols enable seamless integration with control systems and allow for remote monitoring and control of pressure measurements.
When selecting a pressure sensor, it is crucial to consider the power supply requirements. Pressure sensors typically require a DC power supply, which can be 5, 12, or 24 volts. Choose the appropriate power supply voltage based on the availability and compatibility with your system requirements.
By taking into account the desired output type, communication options, and power supply compatibility, you can choose a pressure sensor that best suits your application needs and facilitates seamless integration into your overall system.
Operating Environment
It is important to consider the environmental specifications of a pressure sensor to ensure its proper operation and longevity.
Every sensor is designed to operate within specific ambient temperature and humidity ranges. Carefully review the environmental specifications provided by the manufacturer to ensure that the operating conditions of your intended application align with the recommended ranges.
Factors such as temperature extremes, excessive humidity, exposure to dust or corrosive substances, or other environmental challenges can potentially damage the sensor over time.
By operating the pressure sensor within the specified environmental conditions, you can maximize its performance, accuracy, and overall lifespan. It is essential to create a suitable operating environment and take necessary precautions to protect the sensor from any adverse conditions that may lead to premature failure or inaccurate measurements.
Accuracy
Inaccurate readings can significantly impact the performance of the system, so let’s understand the concept carefully.
Linearity is a key aspect to consider when selecting a pressure sensor. It refers to the sensor’s ability to provide an electrical output that is directly proportional to the applied pressure.
In other words, as the pressure increases or decreases, the electrical output should accurately and consistently vary in the same proportion. A linear relationship between the pressure and the electrical output ensures reliable and precise measurements, enabling better performance and accuracy in the system.
Hysteresis is another important consideration when evaluating pressure sensors. It refers to the difference in output readings between increasing and decreasing pressure cycles, even when the applied pressure returns to the same starting point.
For example, if the pressure increases from 1 psi to 5 psi and then decreases back to 1 psi, but the sensor indicates a reading of 1.2 psi instead, there is a hysteresis of 0.2 psi.
Minimizing hysteresis is crucial for achieving accurate and consistent pressure measurements, as it ensures that the sensor’s output closely tracks the actual pressure changes in both increasing and decreasing directions.
Hysteresis is the non-linear response observed in pressure sensors due to the mechanical movement of the diaphragm. The diaphragm, a key component within the sensor, moves back and forth in response to the applied pressure.
However, this movement is not perfectly constant and can exhibit some lag or lead. As a result, there can be a difference in the measured values at the same pressure point, causing an imbalance in the sensor’s output.
The third thing is repeatability. Basically, it is a combination of hysteresis and linearity.
Every time you increase or decrease the pressure, it is determined as to in what average the pressure shows its value. If there is a vast difference in every cycle, then it’s a major issue and the sensor needs to be checked or replaced. So, the accuracy is combined and shown to you in +-%FS (Full Scale).
Pressure Reading
Depending on the type of pressure reading needed, there are various options available:
A) Absolute Pressure: This measurement is relative to perfect vacuum (zero pressure reference point).
B) Gauge Pressure: The most common type, it measures pressure above atmospheric pressure. Gauge pressure readings are often used in industrial applications.
C) Differential Pressure: This measurement calculates the difference between two inlet pressures. It is commonly used in flow rate calculations and filtration systems.
D) Sealed Pressure: This refers to pressure measured with respect to atmospheric pressure at sea level. It provides a reference point for atmospheric conditions.
E) Compound Pressure: This type of measurement accounts for both positive and negative pressure values. It is suitable for applications where pressure can fluctuate in both directions.
F) Vacuum Pressure: Vacuum pressure measurements indicate pressure lower than atmospheric pressure. It is commonly used in applications such as vacuum pumps and suction systems.
Media Type
Depending on the application, you need to verify if the pressure sensor is suitable for measuring the specific medium like liquid, gas, or any other substance.
The sensor’s design and specifications should align with the properties and characteristics of the medium to ensure accurate and reliable pressure measurements.
Resolution
The resolution of a pressure sensor is nothing but its ability to detect and display the smallest change in pressure with high accuracy. Got it? It represents the sensor’s level of sensitivity in capturing even the most subtle fluctuations in pressure.
A sensor with higher resolution provides finer measurement capabilities, enabling precise monitoring and control of pressure in various applications.
The Material used for the Enclosure
When choosing a pressure sensor, it is crucial to consider the installation environment, whether it is classified as hazardous or non-hazardous. Understanding the material composition of the sensor enclosure is essential to ensure its resistance to corrosion and potential damage, guaranteeing its durability and longevity in challenging conditions. Thus in this post we studied general specifications of a pressure sensor.
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