EJX438A Gauge Pressure Transmitter with Remote Diaphragm Seal

EJX438A Gauge Pressure Transmitter with Remote Diaphragm Seal – Introduction

The Yokogawa EJX438A is a high-performance gauge pressure transmitter designed for industrial applications that require the use of a remote diaphragm seal. It belongs to Yokogawa’s premium EJX-A series, which uses the company’s advanced DPharp digital sensor technology for superior accuracy, long-term stability, and reliability.

By using a remote diaphragm seal, the transmitter isolates the process fluid from the pressure sensor through a diaphragm and fill fluid system. This makes the EJX438A ideal for processes involving corrosive, abrasive, high-temperature, viscous, or sanitary fluids, or wherever direct contact between the sensor and the medium is not acceptable.

Key Features

High Measurement Performance

• Gauge pressure measurement
• Accuracy: ±0.15% of span
• Fast response time of 200 ms
• Wide rangeability (turndown): 100:1
• Suitable for liquids, gases, and steam

Advanced DPharp Digital Sensor

• Active, self-diagnosing resonant silicon sensor
• Excellent long-term stability
• Continuous health monitoring for improved safety

Remote Diaphragm Seal System

• Protects the transmitter from harsh process conditions
• Ensures measurement integrity in extreme or contaminated media
• Available with various seal types, fill fluids, and capillary lengths

Output and Communication Options

• Standard 4–20 mA DC output
• Digital communication options depending on model:
• HART
• FOUNDATION Fieldbus
• PROFIBUS PA
• BRAIN

Industrial Robustness and Safety

• Heavy-duty construction with high-grade materials
• Designed for demanding environments
• Suitable for safety instrumented systems (SIS)
• SIL 2 (single configuration)
• SIL 3 (redundant configuration)

Typical Applications

The EJX438A is widely used in industries such as:

• Oil & Gas
• Petrochemical & Chemical
• Power generation
• Refining
• Water & wastewater
• Pulp & paper
• Food & beverage (sanitary seals)

Typical use cases include:

• Corrosive or abrasive fluid measurement
• High-temperature or vacuum service
• Viscous or crystallizing media
• Steam systems
• Tanks and reactors requiring remote mounting

Product Status

The EJX438A has been discontinued by Yokogawa (effective late 2024).
Recommended successor models include:

• EJXC80A Series
• EJAC80E Series

These new models provide improved performance and updated diaphragm-seal configurations.