Sealed Gauge Differential Pressure Transmitter with Multi-Protocol Output

1. Why You Need a Sealed Gauge Transmitter

Not every measurement should be referenced to the local atmosphere. In sealed systems, high-altitude installations or applications where humidity and contaminants would enter an open vent, a sealed gauge transmitter provides a fixed, hermetically sealed reference so the reading is stable and protected from the environment. By offering gauge, absolute and sealed gauge configurations in a single platform, this instrument lets one transmitter serve diverse measurement needs — from general process pressure to precise low-range differential measurement — with flexible digital communication to match any control system.

2. Working Principle of the Sealed Gauge Transmitter

The transmitter measures pressure using a sealed reference: in sealed gauge mode, the reference chamber is hermetically sealed at a fixed pressure, protecting the sensor from humidity and contamination while providing a stable baseline. In gauge mode it references atmosphere, and in absolute mode it references a vacuum. The sensor converts the measured pressure into an electrical signal, which is output as 4-20 mA, 0-5 V, 0-10 V or RS485, with HART, Modbus or Profibus digital communication layered on top for configuration and diagnostics.

3. Sealed Gauge Design Advantages

• Sealed reference protection: hermetically sealed chamber resists humidity and contamination.
• Three measurement types: gauge, absolute and sealed gauge in one platform.
• Multi-protocol communication: HART, Modbus and Profibus options.
• Wide range: from 0-0.1 kPa to 3 MPa covers low to medium pressures.
• Flexible outputs: 4-20 mA, 0-5 V, 0-10 V and RS485.

Common Measurement Challenges & Solutions

Why Choose Our Sealed Gauge Pressure Transmitter?

• Gauge, absolute and sealed gauge measurement types
• Hermetically sealed reference resists humidity and contamination
• HART, Modbus and Profibus communication options
• 4-20 mA, 0-5 V, 0-10 V and RS485 outputs
• Wide 0-0.1 kPa to 3 MPa measurement range
• Suitable for low-range differential measurement
• 15-30 V DC power supply
• Stable reference for high-altitude and sealed systems
• Multi-point networking via RS485
• Flexible single-platform configuration

Q: What is a sealed gauge pressure transmitter?

A sealed gauge pressure transmitter measures pressure relative to a fixed, hermetically sealed reference pressure rather than open atmospheric pressure. The sealed chamber protects the sensor from humidity, dust and contamination that would enter an open vent, while providing a stable baseline for measurement. Sealed gauge is used in high-altitude installations, sealed systems and humid environments where an open atmospheric vent would cause drift or sensor damage.

Q: What is the difference between sealed gauge and gauge pressure?

Gauge pressure is referenced to the open, local atmosphere, so the reading changes with weather and altitude, and the vent can admit moisture and contaminants. Sealed gauge pressure is referenced to a fixed, hermetically sealed chamber, protecting the sensor from the environment and providing a stable reference independent of immediate atmospheric changes. Sealed gauge is preferred in humid, dirty or sealed-system applications where an open vent is undesirable.

Q: What is the difference between gauge, absolute and differential pressure?

Gauge pressure is measured relative to local atmospheric pressure, absolute pressure relative to a perfect vacuum, and differential pressure as the difference between two pressure points. This transmitter supports all three configurations, allowing one platform to serve different measurement references. The choice depends on whether the process needs a reading relative to ambient (gauge), independent of ambient (absolute), or the difference between two taps (differential).

Q: What communication protocols are supported?

The transmitter supports HART, Modbus and Profibus digital communication protocols. HART superimposes digital data on the 4-20 mA analog signal for configuration and diagnostics. Modbus RTU over RS485 enables multi-drop digital networking with PLCs and SCADA. Profibus is a fieldbus standard used in many European industrial systems. This multi-protocol support ensures compatibility with a wide range of control systems.

Q: What output signals are available?

The transmitter provides 4-20 mA analog, 0-5 V and 0-10 V voltage, and RS485 digital outputs. The 4-20 mA loop is the standard for long cable runs and PLC/DCS inputs, voltage outputs suit systems preferring voltage signals, and RS485 enables digital multi-drop communication. This flexibility allows the transmitter to integrate with virtually any control or monitoring system.

Q: What is the measurement range?

The transmitter covers a wide measurement range from 0-0.1 kPa to 3 MPa, spanning low-range differential measurements (such as HVAC duct pressure) to medium-range process pressure. The wide span coverage makes it versatile for air-flow, filter differential, level and general pressure applications. The specific range is configured to match the application's operating pressure for best accuracy.

Q: Why use a sealed reference instead of an open vent?

A sealed reference protects the sensor from humidity, dust and corrosive gases that an open atmospheric vent would admit, and it provides a stable baseline independent of immediate atmospheric fluctuations. In humid environments, an open vent allows moisture to condense inside and damage the electronics; in high-altitude or sealed systems, the open reference would drift with ambient pressure. A sealed reference eliminates these problems for more reliable measurement.

Q: Can it measure low differential pressure?

Yes. The transmitter's range extends down to 0-0.1 kPa, enabling precise low-range differential measurement for applications such as HVAC duct pressure, cleanroom differential and filter monitoring. Low-range differential measurement requires a sensitive, stable sensor, and the sealed reference helps maintain accuracy at these small spans. This capability makes the transmitter suitable for both process and building-automation applications.

Q: What power supply does it need?

The transmitter operates on a 15-30 V DC power supply, compatible with standard industrial power systems. The two-wire 4-20 mA version draws power from the signal loop, while RS485 and voltage-output versions require a separate supply. The specified range provides flexibility for field and panel installations using common 24 V DC supplies.

Q: Where are sealed gauge transmitters used?

Sealed gauge transmitters are used in HVAC duct and differential pressure measurement, water and environmental filter monitoring, sealed process vessels, and automation systems requiring flexible protocol integration. They are particularly valuable in humid, dirty or high-altitude environments where an open atmospheric vent would compromise reliability, and in plants with diverse control systems needing multi-protocol support.