Differential Pressure Transmitter with HART and Exia/Exd Certification

1. Why You Need It

Flow, level and filter monitoring all depend on measuring the pressure difference between two points — and in hazardous areas, that measurement must also be intrinsically safe or flameproof. This differential pressure transmitter combines HART communication with Exia/Exd certification and an LCD display, delivering accurate DP measurement for flow, level and filtration in classified locations. Its stainless steel construction and IP67 rating make it a robust, safe choice for oil, gas and chemical processes.

2. Working Principle

The transmitter measures the pressure difference between a high-pressure and a low-pressure connection. A diaphragm sensor detects the differential, and the electronics convert it to a 4-20 mA HART signal. The Exia (intrinsically safe) and Exd (flameproof) protection methods allow operation in hazardous areas — Exia limits energy to prevent ignition, while Exd contains any internal explosion. The LCD shows the DP value locally for commissioning and diagnostics.

3. Key Advantages

• Differential pressure measurement
• HART protocol
• Exia and Exd certification
• Integrated LCD display
• 4-20 mA output
• IP67 protection
• Stainless steel construction
• 0-10 MPa pressure range
• Two-wire and three-wire options
• Suitable for flow, level and filtration

Common Pain Points & Solutions

Application Cases

Technical Specifications

FAQ

Q: What is a differential pressure transmitter?

A differential pressure (DP) transmitter measures the difference in pressure between two points and converts it into a standard output signal such as 4-20 mA. DP is the workhorse measurement for flow (via orifice plates or primary elements), liquid level (via hydrostatic head) and filter condition (via pressure drop). The DP principle is widely used because it is accurate, robust and well understood.

Q: What does Exia/Exd certification mean?

Exia means intrinsically safe — the transmitter's electrical energy is limited so it cannot ignite a flammable atmosphere, suitable for Zone 0 and Zone 1. Exd means flameproof — the enclosure contains any internal explosion, suitable for Zone 1. Having both options lets the transmitter be specified for the appropriate hazardous-area classification of the installation.

Q: Does it have a local display?

Yes, it has an integrated LCD display showing the differential pressure locally. This aids commissioning, troubleshooting and routine checks, letting technicians confirm the measurement without a separate indicator or handheld communicator.

Q: What is HART communication?

HART is a digital protocol superimposed on the 4-20 mA signal. It enables bidirectional communication for remote configuration, calibration and diagnostics without additional wiring. HART also supports multi-variable data, which is useful for DP transmitters that can calculate flow or level from the differential.

Q: What applications use DP measurement?

DP transmitters are used for flow measurement (with orifice plates, venturis or other primary elements), liquid level in sealed tanks (via hydrostatic head), filter and strainer differential monitoring, and pump performance monitoring. Anywhere a pressure difference is the meaningful quantity, a DP transmitter is the appropriate instrument.

Q: What is the pressure range?

The pressure range is 0-10 MPa, covering a wide span of DP applications from low filter differentials to high-pressure flow and level measurement. The span is configured for the specific application.

Q: What is the protection grade?

The housing is IP67 rated, protecting against dust and temporary water immersion. Combined with stainless steel construction, this makes the transmitter durable in outdoor, washdown and harsh process environments.

Q: How is it wired?

The transmitter supports both two-wire and three-wire configurations. The two-wire 4-20 mA loop is the most common and carries both power and signal, simplifying wiring. The three-wire option is used where a separate power and signal path is required.

Q: How does DP measure liquid level?

DP measures liquid level by sensing the hydrostatic pressure at the bottom of a vessel and subtracting a reference (either atmospheric for open tanks, or the vapor space for sealed tanks). The resulting differential is proportional to the liquid height. This is a standard, reliable method for level measurement in sealed and pressurized vessels.

Q: Where is it used?

It is used in oil and gas metering, chemical reactors, filter skids and power plant boilers, particularly in hazardous areas. It provides safe, accurate differential pressure measurement for flow, level and filtration in classified locations.