Rheonik RHE21 Ex d Field Mount Mass Flow Transmitter

An explosion-proof brain for Rheonik Coriolis sensors

The Rheonik RHE21 is a multifunction mass flow transmitter in a flameproof stainless steel housing, intended for general and critical process flows, feed stock transfers, custody transfer, well head production and offshore work. It converts the signals of any Rheonik Coriolis sensor into mass flow, volume, density and temperature, with positive, negative and net totalizers for both mass and volume. A backlit colour display and three behind-glass buttons give local access without opening the housing.

Because the enclosure is Ex d, the transmitter can be mounted in the hazardous area itself, which shortens the sensor cable to 3 m or 10 m, or runs to an intrinsically safe terminal box for a custom cable length.

Features from the datasheet

• Wall or pipe bracket mounting; SS316 corrosion-resistant housing available.
• Advanced functions: Net Oil, Baume/Brix, percent solids, standard density and standard volume to API MPMS Chapter 11.
• Assurance View diagnostics with the Assurance Factor value and colour-changing display.
• Password-protected setup and upload/download of configuration files.
• USB connection for a PC running RHECom software (Free, Pro and Pro+ versions).

Technical specification

Choosing the software package

Five packages build on each other. SO provides mass flow, temperature, fixed and calculated density, batch control and diagnostics. DO adds live density, volume from measured density and Brix/Baume units. AF adds the Assurance Factor, a PID controller for the analog output and partly filled pipe management. GV brings API standard density and volume, Net Oil and concentration calculations. CT adds the hardware lock switch for sealing. The Fluid Transfer package also offers Precision Flow Analysis, which raises the update time to 4 ms for fast-fill measurements as short as 0.5 s.

Ordering and housing codes

Housing codes are E3 and E4 (SS 316L Ex d(e), wall or hook, with 3 m or 10 m cable), EP (panel mount, 10 m cable), E5 (two terminal boxes) and H1 to H3 (stainless Ex d with 1/2 in NPT entries). Power codes are D1, A1 and U1. I/O codes include S1, S2, P1, P2, SH, PH and CH, where H adds HART and CH also adds the analog input. Approval codes are AS, A2, A1, CS, C2 and C1, printed with their Ex markings in the datasheet. Cable entries can be changed to NPT or M20 variants.

Approval markings as printed

The datasheet prints the labelling for each code. A1 (Zone 1, 2) carries ATEX II 2(1)G Ex db eb [ia Ga] IIC T4 Gb and the matching IECEx marking; A2 (Zone 2) carries II 3(1)G Ex db ec [ia Ga] IIC T4 Gc; AS is the safe-area associated equipment code [Ex ia Ga] IIC. For North America, C1 is Class I, Div. 1, 2 (Zone 1, 2) with Ex db [ia Ga] IIC T4 Gb, C2 is Class I, Div. 2 (Zone 2) and CS is the safe-area associated equipment code. Where a sensor and the transmitter are installed in different zones the intrinsically safe sensor circuit is what links them, so verify both labels for your exact configuration.

Practical notes

Sensor and transmitter must carry matching approvals for the installation zone. The dual supply option lets the transmitter run from AC when present and from DC, including a battery, if AC fails. The datasheet notes that tamper-proof seals can be applied once the lock switch is set. RHECom Free allows full setup and data logging at no cost; Pro and Pro+ add trending and a simulator.

Use in oil and gas

Wellhead, production manifolds, offshore decks and loading terminals in the Gulf are typical locations for an explosion-proof flow computer with built-in API volume corrections.

Selection and installation notes

A mass flow transmitter must match the sensor it is connected to, so confirm the sensor model, the cable length, the supply voltage, the output types and the area classification before ordering. Keep the signal cable away from power cables, ground the shield as described in the manual, protect the housing from direct heat and water ingress and record the calibration factors and zero values at commissioning. Use the correct cable glands and seals, particularly in hazardous areas.

Information needed for a quotation

Send the full model code, the quantity, the delivery location in Oman or the GCC, the intended use and any accessories needed, so that the complete package can be quoted together.

Documents and supply information

The manufacturer data sheet is attached to this page and should be read together with the project specification and the site risk assessment before a purchase is confirmed. Ratings, standards and dimensions are quoted as printed on that sheet. Lead time, stock position and certificates available with the shipment are confirmed in the quotation, and we supply to Oman and the wider GCC region for industrial, utility and building services projects.

Related items

Compatible sensors are the Rheonik RHM series; see flow and process measurement for related equipment. Send the sensor model, zone and signal needs and we will quote; confirm the full part number before ordering.