Views: 50 Author: Site Editor Publish Time: 2025-10-10 Origin: Site
Today we will talk about the common pressure types and essential specifications for pressure transducers to assist you in your selection process.
1. Understanding Pressure Types
Pressure transducers are categorized based on the reference point used for measurement. The table below outlines the four main types.
Pressure Type | Definition / Reference Point | Common Example |
Absolute | Measured against a perfect vacuum (zero pressure) | Atmospheric pressure measurement for weather stations |
Gauge | Measured against the current ambient atmospheric pressure | Tire pressure measurement |
Sealed Gauge | Measured against a fixed, sealed reference pressure (not zero) | Similar to absolute, but reference is a fixed pressure instead of vacuum |
Differential Pressure | Measures the difference between two applied pressures | Flow measurement in systems |
2. Key Specifications Explained
When selecting a pressure transducer, paying attention to the following specifications will ensure it meets your application's requirements.
Specification Category | Key Parameters to Consider |
Pressure Range | The minimum and maximum pressure the device is designed to measure. Can be from Vacuum (Vac) to tens of thousands of psi |
Accuracy | Usually expressed as a percentage of Full Scale (FS), e.g., ±0.25% FS, ±0.5% FS, or ±1.0% FS |
Output Signal | The electrical signal representing the pressure reading, such as 4-20 mA, 0-5/10 V, or 0.5-4.5 VDC |
Electrical Connection | How the transducer is powered and connected, including supply voltage (e.g., 12-24 VDC) and signal wiring (2-wire, 3-wire) |
Process Connection & Material | The mechanical interface (e.g., 1/4" NPT(M), M20x1.5) and the wetted materials (e.g., 17-4PH SS, 316L Stainless Steel) in contact with the medium |
Environmental Ratings | Includes operating temperature range (e.g., -10°C to +60°C) and enclosure protection rating (e.g., IP65, NEMA 4X) |
Long-Term Stability | The maximum change in output per year, typically expressed as a percentage of full scale per year (e.g., ≤±0.3%FS/year) |
3. Application and Selection Tips
Match the Pressure Type to Your Need: For most industrial processes where you want to know the pressure inside a vessel relative to the outside air, a Gauge Pressure sensor is standard. Use Absolute Pressure sensors when the measurement is independent of atmospheric changes, and Differential Pressure for measuring flow or level.
Select the Right Range and Accuracy: For the highest quality data, it is recommended to operate between 10% and 90% of the transducer's full-scale range. Don't choose an overly large range for a small pressure, as it reduces measurement resolution. Similarly, select an accuracy that meets your needs without overpaying; a ±0.5% FS accuracy is common for general industrial use.
Consider the Medium and Environment: Ensure the wet materials (like 316L Stainless Steel) are compatible with your medium to avoid corrosion. Also, verify that the operating temperature range and ingress protection (IP or NEMA rating) are suitable for the installation environment.
