Yokogawa EJA118E Diaphragm Seal DP Transmitter Unit

Module Feature

EJA118E is Yokogawa EJA-E series DPharp differential pressure transmitter equipped with two remote diaphragm seals and capillary tubing.

It adopts single-crystal silicon resonant sensor technology, supports dual remote sealing flanges for isolating corrosive, high viscosity, easy crystallization, high temperature process fluid. It outputs 4-20mA analog signal together with HART digital overlay, measures differential pressure as primary variable and static pressure as secondary variable. M capsule provides 40:1 turndown ratio while H capsule supports 20:1. Built-in active capillary fill fluid density compensation, 10-segment signal characterizer and local parameter setting LPS function. SIL2 single unit, SIL3 when redundant configured. This model is discontinued, widely stocked as emergency spare for refinery, chemical and power plant level and flow instrument skid.

Working principle

Process pressure acts on high side and low side diaphragm seals, pressure is transmitted via capillary filling fluid to the DPharp resonant sensor inside transmitter.

Sensor converts differential pressure into resonant frequency signal, internal circuit converts frequency signal to digital value and outputs 4-20mA loop current. HART modem superimposes digital signal on the same loop for remote configuration and secondary static pressure reading. Continuous self-diagnosis detects sensor fault, over-range, loop open/short and capillary abnormal status.

Onboard components

DPharp silicon resonant sensing capsule, signal conditioning PCB, HART communication chip, LCD local indicator, 24VDC loop power circuit, two diaphragm seal assemblies, capillary tubing with fill fluid, terminal block and explosion-proof aluminum housing.

LED indicators

Local LCD display shows DP value, static pressure, percentage range, tag and fault code. Status indicator shows loop and device health.

Hardware self‑diagnosis

Built-in supervision detects sensor over-range, loop open/short, capillary leakage, temperature anomaly and electronics failure. Configuration and fault diagnosis are completed by HART communicator or Yokogawa FieldMate software.

Programming softwareFieldMate, used for range setting, damping adjustment, signal characterization, tag assignment and fault log reading.

Electrical & Process Parameters

Model:EJA118E Brand:Yokogawa Device type:Diaphragm seal differential pressure transmitter Function:DP, static pressure measurement for liquid level, flow and density with remote seal isolation

Mechanical & Structure

Mounting:2” pipe bracket mounting or flange direct installation Protection class:IP67 Housing:Explosion proof aluminum transmitter housing + stainless steel diaphragm seal & capillary assembly

Environmental

Operating temperature:-40℃ ~ +85℃ (transmitter head), diaphragm seal side depends on fill fluid Storage temperature:-40℃ ~ +85℃ Ambient humidity:5~95% non‑condensing

Certification:CE, IEC61508 SIL2 / SIL3 (redundant), ATEX optional Status:Discontinued original Yokogawa process instrument spare

Installation

Isolate loop power and process pressure before replacement.

Avoid bending capillary sharply, install transmitter at suitable elevation to reduce static head error, match correct fill fluid for process temperature, set zero and span, test 4-20mA and HART communication after commissioning.

Interface

Two-wire 4-20mA+HART signal/power terminal, customized flange process connection, capillary to diaphragm seals.

Diagnostic

Fixed output: Diaphragm damage, capillary leakage or blockage. Signal drift: Temperature variation without density compensation, mounting head elevation mismatch. No HART communication: Missing 250Ω loop resistor, reversed polarity or electronics fault. Range alarm: Process pressure exceeds calibrated span.

Product Brief

EJA118E transmitter, Yokogawa remote diaphragm seal DPharp DP instrument spare for chemical and refinery high viscosity / crystallization liquid level measurement skid replacement.