High-Performance Measurement for Very Low Differential Pressure
The Yokogawa EJX120A is a traditional-mount draft range differential pressure transmitter from the premium EJX-A series.
Unlike a standard differential pressure transmitter designed for broader pressure ranges, the EJX120A is specifically optimized for very low differential pressure measurement. Its True Draft Range design makes it suitable for applications where small pressure differences need to be measured reliably and converted into a stable industrial signal.
What Is Draft Range Differential Pressure?
Draft pressure refers to very small pressure differences, often encountered in systems involving air, combustion gases, furnaces, boilers, ventilation, and filtration.
In these applications, the measured differential pressure may be only a few Pa or mmH₂O. A conventional transmitter with a much larger pressure range may not provide the same measurement resolution and stability.
The EJX120A is specifically designed around this type of low differential pressure measurement, making it a better fit when the process signal is small but measurement reliability remains important.
True Draft Range Design
One of the defining features of the EJX120A is its True Draft Range design.
The transmitter supports an E capsule with a measurement span down to 0.025 to 1 kPa, with a corresponding measurement range of -1 to +1 kPa. This makes the EJX120A suitable for applications where differential pressure is close to atmospheric pressure and only a small pressure difference needs to be detected.
This is particularly useful for monitoring draft conditions rather than conventional high-pressure differential measurements.
DPharp Digital Sensor Technology
The EJX120A uses Yokogawa's DPharp single-crystal silicon resonant sensor technology.
The DPharp architecture provides digital sensor processing and is designed to deliver stable, accurate measurement with fast response. Yokogawa positions the DPharp technology as a key part of the EJX-A series performance and reliability.
Fast Response for Dynamic Draft Applications
The EJX120A provides a 150 ms response time.
Fast response can be important in furnace, combustion, ventilation, and other draft applications where pressure conditions can change quickly and operators or control systems need timely process information.
Accuracy and Long-Term Stability
The EJX120A provides ±0.09% of span reference accuracy for its primary differential pressure measurement.
Its specified long-term stability is ±0.15% of URL per year, while its 40:1 rangeability provides flexibility when the actual operating pressure varies within the selected measurement range.
Advanced Diagnostics
The EJX120A incorporates Yokogawa's multi-sensing and diagnostic technologies.
The transmitter can provide diagnostic information that helps identify abnormal conditions such as impulse line blockage or heat trace problems. Yokogawa also provides real-time self-check functions and local parameter setting features for easier field operation.
Communication and Configuration
Depending on the selected configuration, the EJX120A is available with communication options including:
- HART
- BRAIN
- FOUNDATION Fieldbus
- PROFIBUS PA
Remote setup and parameter configuration are supported through the appropriate communication interface, while the Local Parameter Setting function can simplify field configuration.
Key Features
- High-performance draft range differential pressure transmitter
- Traditional-mount configuration
- True Draft Range design
- DPharp single-crystal silicon resonant sensor
- ±0.09% reference accuracy
- 150 ms response time
- 40:1 rangeability
- ±0.15% URL per year long-term stability
- Measurement span down to 0.025 kPa
- 4–20 mA DC output
- HART, BRAIN, FOUNDATION Fieldbus, and PROFIBUS PA options
- Local Parameter Setting
- Advanced multi-sensing diagnostics
- Impulse line blockage detection capability
- SIL-certified configurations available
Typical Applications
The EJX120A is particularly suitable for low differential pressure and draft measurement applications such as:
- Furnace draft monitoring
- Boiler draft measurement
- Combustion air monitoring
- Flue gas pressure measurement
- Forced-draft and induced-draft systems
- HVAC and ventilation systems
- Filter differential pressure monitoring
- Dust collector monitoring
- Cleanroom pressure monitoring
- Process air pressure monitoring
- Low-pressure gas flow applications
FAQ
What is the EJX120A used for?
The EJX120A is designed for very low differential pressure and draft measurement. Typical applications include furnace and boiler draft, combustion air, flue gas, ventilation, and filter differential pressure monitoring.
What makes the EJX120A different from a standard differential pressure transmitter?
The key difference is its True Draft Range design.
The EJX120A is optimized for very low differential pressure, with a measurement span starting as low as 0.025 kPa. This makes it more appropriate for draft applications than a conventional DP transmitter designed for higher pressure ranges.
What is the lowest measurement span of the EJX120A?
For the E capsule, the specified measurement span is 0.025 to 1 kPa, with a measurement range of -1 to +1 kPa.
Can the EJX120A measure furnace draft?
Yes. Furnace and boiler draft are typical applications for a draft range differential pressure transmitter because the pressure difference being measured is relatively small.
Can the EJX120A be used for boiler applications?
Yes. It can be used for applications such as boiler draft, combustion air, and flue gas pressure monitoring where low differential pressure measurement is required.
Can the EJX120A measure filter differential pressure?
Yes. Filter and dust collector monitoring are suitable applications because the transmitter can detect small pressure differences across the filter.
What is the accuracy of the EJX120A?
The official product page specifies ±0.09% of span reference accuracy for the primary differential pressure measurement.
How fast does the EJX120A respond?
The specified response time is 150 ms.
What is the rangeability of the EJX120A?
The EJX120A provides 40:1 rangeability for its primary differential pressure measurement.
Does the EJX120A support HART communication?
Yes. HART communication is available, along with BRAIN, FOUNDATION Fieldbus, and PROFIBUS PA configurations depending on the selected model.
Does the EJX120A have diagnostic functions?
Yes. Yokogawa's multi-sensing technology provides advanced diagnostics, including detection of conditions such as impulse line blockage and heat trace breakage.
Can the EJX120A detect negative differential pressure?
Yes. The draft range configuration includes a measurement range extending from -1 to +1 kPa, making it suitable for applications where the differential pressure can change around zero.
What is the difference between the EJX120A and EJA120E?
Both are Yokogawa draft range differential pressure transmitters, but they belong to different performance series.
The EJX120A is the premium EJX-A series model, while the EJA120E belongs to the EJA-E series. The EJX120A provides higher-performance specifications such as ±0.09% accuracy, 150 ms response, and ±0.15% URL/year stability.
Is the EJX120A suitable for safety applications?
Yokogawa lists Exida and TÜV SIL 2/3 certification for the EJX120A. The exact safety capability depends on the system architecture and selected configuration, so the applicable certificate and safety manual should be checked for the specific order code.
Is the EJX120A still supported by Yokogawa?
Yes. The current Yokogawa product page remains active and provides the EJX120A product information, manuals, general specifications, software, technical information, and drawings.
