Choosing Between Emerson 3051 Models: DP, GP, and Absolute Pressure

When it comes to industrial instrumentation, the Emerson Rosemount 3051 Pressure Transmitter is a trusted workhorse. Its versatility allows engineers to deploy one platform across multiple applications, but the key lies in selecting the right measurement type: DP, GP, or Absolute Pressure. Let’s break down the differences and practical use cases.

1. Differential Pressure (DP)

• Definition: Measures the difference between two pressure points.
• Typical Applications:
• Flow measurement using orifice plates, venturi tubes, or pitot tubes.
• Level measurement in pressurized tanks.
• Monitoring filter or pump performance.
• Range: Up to 2000 psi (137.9 bar) differential emerson.cn.
• Why Choose DP: Ideal when you need to understand how two pressures interact, especially in flow and level calculations.

2. Gauge Pressure (GP)

• Definition: Measures pressure relative to atmospheric pressure (0 psig = ambient atmosphere).
• Typical Applications:
• Monitoring pipeline pressure.
• Ensuring safe operating conditions in compressors and pumps.
• General process monitoring where an atmospheric reference is sufficient.
• Range: Up to 2000 psig (137.9 bar) emerson.cn.
• Why Choose GP: Best for everyday process monitoring where atmospheric conditions are the baseline.

3. Absolute Pressure (AP)

• Definition: Measures pressure relative to a perfect vacuum (0 psia = absolute zero).
• Typical Applications:
• Vacuum distillation processes.
• Reactor monitoring in chemical plants.
• Applications where atmospheric pressure fluctuations would distort readings.
• Range: Up to 4000 psia (275.8 bar) emerson.cn.
• Why Choose AP: Critical for high-accuracy applications where atmospheric changes cannot be ignored.

Comparison Table

Key Takeaway

• Choose DP if you need to measure differences (flow, level).
• Choose GP if you’re monitoring process pressure relative to the atmosphere.
• Choose AP if accuracy is critical in vacuum or sensitive chemical processes.