Rosemount 8705-M Flanged Magnetic Flow Sensor

Rosemount 8705-M flanged magnetic flow sensor and how its code reads

The Rosemount 8705-M is the flanged process sensor of the Rosemount 8700M magnetic flow meter platform. It is a fully welded stainless and carbon steel body with a sealed coil housing, built for conductive liquids and slurries in line sizes from ½ in. (15 mm) to 36 in. (900 mm). Paired with an 8732EM field-mount or 8712EM wall-mount transmitter it forms a complete magnetic flow meter. Seven Star LLC supplies 8705 sensors in Oman and the GCC as an independent supplier in Muscat; the exact liner, electrode and flange must be confirmed per order.

The manufacturer’s example code is 8705 T S A 040 C 1 M0 K5 PD G1 D1 V1 Q8 WG. The positions are base model, lining, electrode material, electrode type, line size, flange type and material, flange rating, coil housing, and options.

8705-M technical specifications

How the 8705-M senses flow

Inside the sensor two coils create a magnetic field across the bore. As conductive liquid moves through the field, a small voltage appears between the measurement electrodes that is directly proportional to the average velocity. The transmitter reads that voltage and, with the sensor calibration number from the nameplate, calculates volumetric flow. The liner insulates the electrodes from the metal pipe and protects the body from the process, so the choice of liner and electrode is chiefly a chemistry and abrasion decision, not an accuracy one.

Accuracy is kept regardless of line size or options because the 16-digit calibration number carries the calibration of each individual sensor. Optional reference electrodes, grounding rings and lining protectors maintain a reliable process ground, which is essential in lined or plastic pipe.

Where the 8705-M fits

The 8705-M is interchangeable with the 8712EM and 8732EM transmitters. For smaller, lighter duties in line sizes 1½ to 8 in. the wafer 8711-M/L can replace it, and for hygienic duties the 8721 is used. A related Rosemount part on our site is the 8732EM transmitter. Process connections include ASME B16.5 Class 150 to 600 in ½ to 24 in., Class 900 and 1500 on selected sizes, B16.47 and AWWA C207 for 30 and 36 in., EN 1092-1 PN10 to PN40, AS2129, AS4087 and JIS B2220.

Selection and ordering checklist for 8705-M

• Pick the liner for chemistry and temperature: PTFE, PFA and PFA+ for aggressive liquids to 177 °C, neoprene or Linatex for abrasive slurry, polyurethane for abrasive water-based duties.
• Pick the electrode: 316L for water, Alloy 276 or tantalum for corrosive acids, titanium for chlorides, platinum-iridium for the most demanding services.
• Check the liner against the flange rating: Class 900 and higher are limited to resilient liners, and PTFE, PFA and ETFE are derated to 1,000 psig at Class 600.
• Select the housing code: M0 is standard, M2 or M4 adds sealed electrode compartments for wet, buried or submerged installations.
• Choose the hazardous-area code, for example K5, K1 or K7, and the quality certificate.
• Add grounding rings, lining protectors or reference electrodes if the pipe is plastic or lined.

Installation, commissioning and maintenance of the 8705-M

Install the sensor with at least five straight pipe diameters upstream and two downstream. Keep the pipe full at the electrode plane. Tighten flange bolts evenly to protect the lining, fit grounding rings or reference electrode to establish a process ground, and use IP68 approved glands and conduit plugs where the sensor may be flooded. Wire the coil and electrode cables to the transmitter, enter the calibration number and run the commissioning diagnostics. Routine maintenance consists of checking cable entries, ground connections and the transmitter diagnostics for coating or high noise; the sensor body has no moving parts.

Typical applications in Oman and the GCC

Flanged magnetic sensors are used on desalination feed and product water, seawater cooling and circulation, produced water, firewater and utility water networks, wastewater, caustic and acid dosing, and slurry lines in mining and cement. Offshore marine paint and a stainless housing option help in coastal installations. Heat, direct sun and dust do not affect the sealed housing, but the ambient limit of 60 °C should be respected with shading when needed.

Information to send with an RFQ for 8705-M

• Line size and flange standard, rating and facing.
• Process liquid, concentration, temperature, pressure, conductivity and flow range.
• Liner and electrode material, electrode type and housing code.
• Transmitter model (8732EM or 8712EM) and mounting.
• Hazardous-area certificate, cable length and any grounding hardware.
• Quantity, project and delivery location.

Documents and quotation

Send the full 8705-M code and we will confirm availability and any official documents we can share for it. The platform data sheet is large, so we confirm the correct file with each quotation.