The yokogawa EJA118E diaphragm sealed differential pressure transmitter is a differential pressure instrument designed for applications where the process medium should not come into direct contact with the transmitter's pressure-sensing assembly. Instead of connecting the sensing element directly to the process, the EJA118E uses remote diaphragm seals connected through capillaries containing fill fluid. This arrangement is particularly useful when the measured medium is viscous, corrosive, likely to crystallise, or otherwise difficult to handle with conventional impulse piping. According to Yokogawa's official documentation, the EJA118E can be used for differential pressure measurement associated with liquid, gas, and steam flow, as well as liquid level, density, and pressure measurement. There is also an important procurement point that should not be overlooked. Yokogawa currently lists the EJA118E as a discontinued product, with discontinuation dated September 30, 2024. The manufacturer identifies the EJXC80A and EJAC80E differential/gauge pressure diaphragm seal systems as replacement products. Therefore, the EJA118E is most relevant today when users are maintaining existing installations, sourcing replacement instruments, reviewing installed equipment, or comparing the older configuration with a current Yokogawa solution.
A diaphragm seal creates a physical barrier between the process fluid and the transmitter's pressure-sensing assembly. Pressure from the process deflects the diaphragm, and that pressure change is transferred through the fill fluid inside the capillary to the transmitter. This design prevents the process medium from entering the sensing assembly while allowing the instrument to measure the pressure difference between the high- and low-pressure sides.
This configuration becomes useful when conventional impulse lines could create maintenance or measurement problems. A thick liquid can accumulate inside a narrow impulse line, while a crystallising process fluid can eventually obstruct the pressure connection. A hot process may also require the sensing instrument to be separated from the process connection. With a remote seal arrangement, the process-facing diaphragm and the transmitter can be configured to suit the installation rather than forcing the sensing element to contact the process fluid directly.
The capillary and fill fluid are therefore not secondary accessories. They form part of the measurement system and can influence the response and temperature behaviour of a remote-seal installation. For that reason, the seal type, fill fluid, capillary length, process temperature, and mounting arrangement should be considered together when selecting or replacing an EJA118E configuration.
The EJA118E belongs to Yokogawa's EJA-E family and uses the company's DPharp digital sensor technology. Yokogawa describes the instrument as having a stable sensor capable of measuring both differential pressure and static pressure. Differential pressure is the primary measurement, while static pressure can be displayed locally or monitored through supported communication functions.
This dual-measurement capability can be useful during process diagnosis because static pressure provides additional information about the operating condition of the transmitter. Instead of looking only at the differential pressure value, an engineer can also consider the static pressure acting on the instrument. The two measurements can therefore help provide a more complete picture when investigating abnormal process behaviour or checking the operating condition of a pressure measurement point.
The EJA118E is not simply a conventional differential pressure transmitter with a seal added to the process connection. Its sensing and digital processing architecture is part of the EJA-E platform, while the remote diaphragm seal system addresses the specific challenges created by difficult process media and installation conditions.
Yokogawa specifies a reference accuracy of ±0.2% of the calibrated differential pressure span for the applicable EJA118E configurations. The manufacturer also specifies an approximately 200 ms response time for differential pressure under the stated test conditions.
These figures are useful for initial comparison, but they should not be interpreted as a guarantee of the same measurement performance under every field installation. Remote diaphragm seals introduce additional factors such as capillary length, fill-fluid behaviour, ambient temperature changes, and process temperature. Yokogawa's specifications therefore distinguish the transmitter's stated performance from the effects that can arise from the complete diaphragm-seal installation.
The EJA118E also provides a static pressure measurement function. The yokogawa EJA118E diaphragm sealed differential pressure transmitter offers a static pressure accuracy of ±0.5% of span under the specified conditions, with the static pressure signal available for monitoring through the indicator or communication functions.
The EJA118E was available with M and H capsules. Yokogawa lists the M capsule with a measurement span of 2.5 to 100 kPa and the H capsule with a span of 25 to 500 kPa. The corresponding rangeability is 40:1 for the M capsule and 20:1 for the H capsule.
This distinction matters because the appropriate capsule depends on the expected differential pressure rather than simply choosing the transmitter with the largest possible range. A measurement point that normally operates at a relatively low differential pressure may benefit from a lower-range capsule, while a higher-pressure application may require the H capsule.
For replacement work, engineers should not select the capsule solely from the process connection or transmitter nameplate. The existing calibrated range, normal operating differential pressure, maximum working pressure, static pressure, seal configuration, and required output should all be checked against the original instrument documentation.
Viscous fluids are among the clearest applications for remote diaphragm seals. When a process fluid is thick or sticky, conventional impulse piping can become difficult to keep clean and responsive. Deposits inside the pressure connection may also affect the pressure transmitted to the sensing element.
A remote diaphragm seal moves the process interface to the seal diaphragm, while the fill fluid carries the pressure signal through the capillary. This can reduce the likelihood that the process medium will enter and obstruct the pressure transmission path inside the transmitter. It does not mean that every viscous application will produce identical measurement performance, because the seal geometry, process temperature, fill fluid, and mounting arrangement still need to be selected correctly.
Crystallising media presents a similar challenge. If the process fluid solidifies around an ordinary pressure connection, the measurement can become difficult to maintain. A properly selected diaphragm seal can isolate the sensing system from direct process contact and provide a more suitable process interface.
Remote seals can also be useful when the process temperature or chemical characteristics make direct connection undesirable. The transmitter can be positioned away from the hottest part of the process while pressure is transferred through the seal and capillary system.
However, the presence of a diaphragm seal does not automatically make the transmitter suitable for every aggressive chemical or temperature condition. The wetted materials, diaphragm material, fill fluid, flange or process connection, maximum working pressure, and temperature limits must be checked for the specific configuration.
This is an important distinction for technical buyers. Rather than treating “diaphragm sealed” as a universal solution, the correct approach is to match the complete seal assembly to the actual process conditions.
The standard EJA118E configuration provides a 4 to 20 mA DC output corresponding to measured differential pressure, while communication options were available for different plant control architectures. Yokogawa's documentation lists BRAIN, HART 5/HART 7, FOUNDATION Fieldbus, and PROFIBUS PA versions, with a low-power 1 to 5 V DC HART configuration also available.
This range of communication options made the EJA118E suitable for integration into different control and instrumentation systems. HART communication, for example, can provide access to configuration and diagnostic information without relying solely on the analogue process signal. Fieldbus versions can be selected where the plant's instrumentation architecture is built around digital field communication.
The correct communication version should therefore be confirmed before purchasing a replacement. A transmitter with the wrong output or communication protocol may be mechanically compatible with an existing installation but still require additional changes to the control system.
Yokogawa identifies self-diagnostics and remote setup as features of the yokogawa EJA118E diaphragm sealed differential pressure transmitter. The instrument also includes local parameter setting options depending on configuration. These functions can simplify commissioning and troubleshooting because engineers can access configuration and diagnostic information without treating the transmitter as a simple analogue-only device.
For maintenance teams, this distinction is useful. A pressure reading that appears unusual does not necessarily indicate a failed sensor. Process conditions, impulse or seal behaviour, configuration, wiring, and instrument status should all be considered during troubleshooting. Diagnostic information can help narrow down the possible causes before a transmitter is removed from service.
The EJA118E uses the four-bolt pressure-retaining construction associated with Yokogawa's EJA-E differential pressure transmitters. Yokogawa also lists SIL-related certification for the product, with the manufacturer's documentation identifying SIL 2 and SIL 3 certification depending on the applicable configuration and safety architecture.
These certifications should not be interpreted as meaning that any installation automatically becomes SIL 2 or SIL 3 simply because an EJA118E is installed. Functional safety depends on the complete safety instrumented function, including the transmitter configuration, proof testing, system architecture, and applicable engineering requirements.
The same principle applies to pressure and mechanical ratings. The transmitter and diaphragm seal should be selected according to the actual process pressure, temperature, connection standard, and required safety margins rather than relying on the product family name alone.
Material selection is particularly important for diaphragm-sealed instruments because the diaphragm and process connection are exposed to the process environment. The available EJA118E configurations included different seal and process connection arrangements, including flush, extended, combination, and inner-diaphragm types. Yokogawa's documentation also provides specific material and connection information for individual configurations.
For this reason, a buyer should avoid assuming that every EJA118E has exactly the same wetted materials or seal construction. The correct configuration should be established from the model code, datasheet, existing nameplate, and process requirements.
Chemical plants often use diaphragm-sealed differential pressure transmitters where process fluids are corrosive, viscous, contaminated, or prone to crystallisation. Typical measurement duties can include liquid level, flow, and differential pressure monitoring, provided the selected seal and materials are compatible with the process.
The remote seal arrangement can be especially useful where impulse piping would be difficult to maintain. Instead of allowing process material to travel through a conventional impulse line towards the transmitter, the pressure interface is established at the diaphragm seal.
The EJA118E can also be found in applications involving process equipment, storage vessels, flow measurement, and other industrial pressure measurement duties. Yokogawa specifically identifies flow, level, density, and pressure measurement as application areas for the instrument.
In power-related processes, remote seals may be useful when the measurement point involves elevated temperatures or difficult-to-maintain impulse connections. In oil and gas facilities, the suitability of a particular configuration depends heavily on pressure rating, process fluid compatibility, hazardous-area requirements, and the selected seal arrangement.
The key point is that the EJA118E should be selected based on the measurement task and process conditions rather than simply by industry name. Two plants in the same industry can require completely different diaphragm seal configurations.
The yokogawa EJA118E diaphragm sealed differential pressure transmitter was designed for differential pressure measurement applications where direct exposure of the pressure-sensing assembly to the process medium would create practical or reliability problems. Its remote diaphragm seals, capillary-based pressure transmission, DPharp digital sensor technology, static pressure measurement capability, communication options, and approximately 200 ms differential-pressure response time made it a useful instrument for demanding process applications.
At the same time, current buyers need to consider its product status carefully. Yokogawa officially lists the EJA118E as discontinued as of September 30, 2024, and identifies the EJXC80A and EJAC80E as replacement diaphragm seal systems. Therefore, the EJA118E remains relevant for existing installations, replacement planning, equipment identification, and technical comparison, while new projects should evaluate the manufacturer's current replacement products.
For an existing EJA118E installation, the most reliable selection approach is to verify the complete model configuration rather than matching the product name alone. The differential pressure range, static pressure, seal type, process connection, wetted materials, fill fluid, capillary length, output signal, communication protocol, and operating temperature should all be checked before procurement. This approach helps ensure that the replacement or equivalent instrument matches the actual measurement system instead of only matching the transmitter body.
The EJA118E is a differential pressure transmitter with remote diaphragm seals. The diaphragm seals separate the process medium from the transmitter's pressure-sensing assembly, while fill fluid inside the capillaries transfers pressure from the process connection to the sensor. Yokogawa specifies the instrument for differential pressure measurement associated with flow, level, density, and pressure applications.
A diaphragm seal is useful when the process medium is viscous, corrosive, crystallising, very hot, or otherwise unsuitable for direct connection to the sensing assembly. It creates a barrier between the process and the transmitter while allowing pressure to be transferred through the fill fluid. The appropriate seal configuration still needs to be selected according to the actual process conditions.
Yokogawa lists ±0.2% reference accuracy for the applicable differential pressure measurement, an approximately 200 ms differential pressure response time, and a rangeability of 40:1 for the M capsule and 20:1 for the H capsule. The instrument can also monitor static pressure, with the published specifications giving ±0.5% of span accuracy under the applicable conditions.
No. Yokogawa officially identifies the EJA118E as discontinued, with a discontinuation date of September 30, 2024. The manufacturer points customers towards the EJXC80A and EJAC80E differential/gauge pressure diaphragm seal systems as replacement products.
H.L.X AUTOMATION offers comprehensive solutions featuring the yokogawa EJA118E diaphragm sealed differential pressure transmitter for demanding industrial applications. As a trusted supplier of premium instrumentation, we provide expert application engineering, competitive pricing, and reliable technical support to help you optimise your process control systems. Contact our experienced team at sales01@hlx8.com to discuss your specific measurement requirements and discover how our advanced pressure transmitter manufacturer partnerships can deliver the precision and reliability your operations demand.
1. Yokogawa Technical Bulletin: "EJA Series Differential Pressure Transmitters - Design Principles and Applications" (2023)
2. International Society of Automation: "Diaphragm Sealed Pressure Transmitter Selection Guide for Process Industries" (2022)
3. Chemical Engineering Magazine: "Advanced Pressure Measurement Technologies for Challenging Process Applications" (2023)
4. Process Control Engineering Journal: "Comparative Analysis of Resonant vs. Capacitive Pressure Sensor Technologies" (2022)
5. Industrial Instrumentation Handbook: "Safety Instrumented Systems and SIL-Rated Pressure Transmitters" (2023)
6. Automation World Technical Report: "Digital Communication Protocols in Modern Process Instrumentation" (2022)
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