Endress+Hauser FMB50 Deltapilot M Hydrostatic Level Transmitter

Endress+Hauser FMB50 Deltapilot M compact hydrostatic level transmitter

The Endress+Hauser FMB50 is the compact member of the Deltapilot M family. It is a gauge pressure transmitter with a metallic process diaphragm that screws, flanges or clamps directly onto the tank wall or a pipe stub, and it converts the hydrostatic pressure of the liquid above it into a level, volume or mass reading. Unlike the FMB51, FMB52 and FMB53, which hang into the liquid, the FMB50 sits at a fixed tapping point, so it suits tanks with a connection below the lowest level.

Seven Star LLC supplies the FMB50 in Oman and the GCC as an independent supplier in Muscat. The sections below explain what the FMB50 offers, how its measuring cell works and what we need from you to quote the right version.

FMB50 technical specifications

These values come from the Endress+Hauser technical information for the Deltapilot M FMB50 to FMB53 series. Exact limits depend on the measuring cell, process connection and options chosen, so always check the nameplate code of the version you quote.

How the FMB50 CONTITE measuring cell works

A liquid column produces a pressure that is proportional to its height and density. The FMB50 senses that pressure on its process diaphragm and passes it, through an oil fill, to a silicon measuring element. The element sits between the process diaphragm and a second, rear diaphragm, which is the idea behind the CONTITE cell: the sensing element is sealed off from the outside air, so condensation and aggressive gases in the vent path cannot reach it.

The electronics correct the signal with the cell temperature, and a linearization table of up to 32 points can be entered on site or remotely. That table lets the FMB50 output a linear level in a spherical, horizontal cylindrical or cone-bottom vessel instead of a raw pressure. For tanks under gas pressure, two transmitters and a PLC can work out level from the pressure difference.

FMB50 process connections and hygienic adapters

The FMB50 is available with a G 1½ A thread (316L, with an Alloy C276 bottom section in one variant) and a 1½ MNPT thread, each weighing about 0.8 kg. EN, ASME and JIS flanges are offered, and hygienic users can choose from a long list: DIN 11851, Tri-Clamp, Varivent type N, SMS 2 in, NEUMO D50, DRD 65 mm, the universal process adapter and Anderson adapters. Wetted hygienic parts have surface roughness Ra below 0.76 µm as standard.

Because the overpressure rating of the connection can be lower than that of the cell, the datasheet states that the device is set at the factory to the lower value. If you need the full cell range, pick a connection with a higher rating.

Where the FMB50 fits and related Deltapilot M models

The Deltapilot M family covers four mounting styles that share one electronics platform. The FMB50 is the external, wall-mounted version. The FMB51 is a rod version for open tanks and sumps, the FMB52 is a cable version with a threaded or flanged top connection, and the FMB53 is a cable probe hung from a suspension clamp with the housing mounted separately. If the vessel has no connection below the lowest level and you have to measure from above, one of those three is the better fit. For high accuracy up to SIL 3, the Deltapilot S FMB70 is the sibling to look at, and for plain process pressure the Cerabar family such as the PMP11 serves instead.

Selecting and ordering an FMB50

• Measuring cell: choose the cell so the maximum hydrostatic pressure, plus any top pressure, stays within its range. A hydrostatic head of 600 mbar plus 300 mbar of top pressure needs a cell of at least 1.2 bar.
• Turn down: a smaller span lowers the accuracy; the datasheet gives a formula for each cell, so set the span as close to the real level range as practical.
• Output: HART for most plants, PROFIBUS PA or FOUNDATION Fieldbus for fieldbus segments, and IO-Link where the FMB50 connects to a sensor master. IO-Link is not available on the FMB51 to FMB53.
• Process connection and diaphragm: match the thread, flange or hygienic fitting to the vessel and pick Alloy C276 plain or gold-rhodium coated, which protects against hydrogen diffusion in aqueous solutions.
• Fill fluid: inert oil or the synthetic food-grade oil; oxygen cleaning and paint-wetting-free cleaning are available as service options.
• Approvals: the datasheet lists ATEX, IECEx, FM, CSA and NEPSI as families of Ex approvals, plus ASME BPE conformity for the FMB50 only. Confirm the exact one for your area when we quote.

FMB50 installation, commissioning and maintenance

Mount the FMB50 below the lowest measuring point and keep it out of the filling curtain, the tank outflow and any zone hit by agitator pulses. A shutoff valve in front of the transmitter makes calibration and functional checks easier. For liquids that harden when cold, include the device in the tank insulation. In gas service, fit it above the tapping point so condensate drains back, and on steam use a siphon.

The orientation influences zero, so the unit is preset at the factory and any remaining position shift can be corrected with the keys on the electronics or by digital command. Commissioning is menu driven with guided application menus, and the 4 to 20 mA test signal can be measured at the test terminals without breaking the loop. In service, check the diaphragm for build-up on sticky media and keep the cable entry seal and cover tight, because the housing rating depends on them.

Typical FMB50 applications in Oman and the GCC

In Oman and the GCC the FMB50 is a common choice for day tanks and storage tanks of water, treated water and chemicals in desalination and water treatment plants, for cooling water and condensate vessels in power stations, and for utility tanks in oil and gas and petrochemical sites. Gulf sites bring strong sun, dust and salt air, so the stainless F15 housing, a proper cable gland and a sunshade for tanks in full sun are worth specifying. Hygienic fittings suit food, beverage and pharmaceutical lines.

Information to send with an FMB50 RFQ

• Part number FMB50 and, if known, the full order code from the nameplate or an existing unit.
• Medium, density range and the lowest and highest level, or the span in mbar or bar.
• Process temperature, any top pressure or vacuum, and cleaning or steam-out conditions.
• Required output (HART, PROFIBUS PA, FOUNDATION Fieldbus or IO-Link) and supply.
• Process connection type and size, diaphragm material and hazardous-area classification.
• Required certificates such as 3.1 material or calibration, and quantity.

Documents and quotation

A copy of the Endress+Hauser technical information covering the Deltapilot M FMB50, FMB51, FMB52 and FMB53 is attached on this page, so you can check ranges, connections and options before ordering.

Send us the FMB50 specification above and Seven Star LLC will prepare a quotation for delivery to Oman and the GCC.