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.
|
Parameter / Feature |
EJX438A (Gauge + Remote Diaphragm Seal) |
|
Measurement type |
Gauge pressure (relative pressure) |
|
Accuracy (Reference) |
± 0.15 % of span |
|
Response time |
≈ 200 ms |
|
Rangeability (Turndown) |
Up to 100:1 |
|
Pressure (Span) Ranges |
Example spans: 0.035–3.5 MPa and 0.16–16 MPa (depending on seal / configuration) |
|
Output Signal / Communication Options |
4–20 mA DC + optional digital communication (e.g. HART, BRAIN, FOUNDATION Fieldbus, PROFIBUS PA) |
|
Remote Diaphragm Seal + Capillary System |
Yes — isolates process fluid; pressure is transmitted via fill fluid in capillary/seal to sensor. Useful for corrosive, abrasive, high-temperature or contaminant-sensitive fluids. |
|
Diagnostics & Advanced Sensor |
Uses “DPharp” digital active sensor with self-check/diagnostic capabilities; can detect issues such as impulse-line blockage. |
|
Safety / Functional Safety |
Certified by TÜV / Exida; suitable for SIL 2 (single transmitter) and SIL 3 (redundant configuration) per IEC 61508 / IEC 61511. |
|
Process fluid compatibility |
Liquids, gases, or steam — enabled by remote diaphragm seal. |
|
Status |
Discontinued (since 30 September 2024) — manufacturer recommends replacing with newer models (e.g. EJXC80A, EJAC80E) for new projects. |
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