Yokogawa EJA120A Differential Pressure Transmitter

1. General Description

The Yokogawa EJA120A Intelligent Differential Pressure Transmitter is a reliable and accurate device. Engineers design it for measuring draft range pressure in industrial settings. The EJA120A Yokogawa transmitter uses DPharp active sensor technology. It has a strong design that provides long-term stability, accuracy, and durability.

The EJA120A is ideal for pressure measurement in processes involving low-pressure gas, air, or steam systems. Industries like oil and gas, petrochemical, power generation, HVAC, and water treatment commonly use it. In these fields, keeping precision at low differential pressures is crucial. Its intelligent digital capabilities ensure high performance, easy calibration, and reduced maintenance needs over long-term operation.

2. How to Check if a Pressure Transmitter is Working

To check if a pressure transmitter, like the Yokogawa EJA120A, is working properly, follow these steps. First, ensure it has the correct power supply voltage. The voltage should be between 10.5 and 32 volts. VDC).

Check that the output signal is in the expected 4–20 mA DC range. Do this when you connect it to a control system or multimeter. Apply a known pressure to the sensing ports and observe if the transmitter responds proportionally. Additionally, review HART communication data to confirm sensor stability and diagnostic status.

3. Yokogawa EJA120A Technical Specifications

l Model: EJA120A

l Type: Intelligent Differential Pressure Transmitter

l Measurement Type: Differential Pressure (draft range)

l Accuracy: ±0.2% of span (±0.1% with /HAC option)

l Response Time: 300 ms (with /F1 option)

l Output Signal: 4 to 20 mA DC with HART communication

l Power Supply Voltage: 10.5 to 32 VDC

l Operating Temperature Range: -40°C to +85°C

l Maximum Working Pressure (MWP): 50 kPa (0.5 kg/cm²)

l Pressure Measurement Capability: Suitable for low-pressure gas, air, and steam systems

l Construction: Rugged and weather-resistant for long-term field use

4. Features

l Yokogawa’s DPharp Active Sensor Technology:

l Delivers superior accuracy, stability, and fast response, ensuring precise differential pressure measurement across varying conditions.

l Intelligent Differential Pressure Transmitter:

l Provides digital communication and diagnostics through HART protocol for efficient setup and maintenance.

l Rugged Construction:

l Built for long-term durability in harsh industrial environments, maintaining consistent performance over time.

l Self-Diagnostics and Advanced Monitoring:

l Continuously checks transmitter health, alerting operators of potential sensor or wiring issues.

l Reliable Output Signal:

l Offers a stable 4–20 mA DC output signal, ensuring seamless integration with process control systems.

5. Applications

l Oil and Gas Pipelines – Low differential pressure monitoring and control

l Petrochemical Processing – Accurate draft and pressure measurements

l Power Generation Facilities – Boiler draft and air flow applications

l Water and Wastewater Treatment Plants – Filter and pump control systems

l HVAC Systems – Airflow and pressure control in industrial ventilation

6. Yokogawa EJA120A Installation Procedure Step by Step

1. Preparation

Verify the installation site is clean and properly ventilated.

Review the Yokogawa EJA120A user manual and datasheet before starting.

Ensure all mounting accessories and electrical tools are available.

2. Mounting the Transmitter

Choose a stable location minimizing vibration and temperature fluctuation.

Securely mount the transmitter using the provided brackets and hardware.

3. Connecting Pressure Lines

Connect the high- and low-pressure ports to the process line.

Ensure fittings are tight and leak-free to maintain measurement accuracy.

4. Electrical Connections

Connect the power supply (10.5–32 VDC) per the wiring diagram.

Confirm correct polarity and grounding for safety.

5. Configuration

Power on the transmitter and configure it using a HART communicator or local display.

Set the pressure range, output scaling, and engineering units according to the application.

6. Testing

Apply known pressures to validate accuracy.

Monitor the 4–20 mA output signal using a multimeter or control system to confirm proper response.

7. Final Checks

Inspect for any leaks or loose fittings.

Ensure environmental protection and sealing are intact for long-term operation.

7. Yokogawa EJA120A Related Part Numbers

l EJA110A: For standard differential pressure ranges

l EJA120E: Advanced model with enhanced diagnostic and communication functions

l EJA130A: High static differential pressure transmitter for critical applications

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