Product Overview
E+H Waterpilot FMX21 Hydrostatic Level Transmitter
Waterpilot FMX21
The Endress+Hauser Waterpilot FMX21 is a compact, submersible hydrostatic transmitter designed for continuous level and height measurement in fresh water, wastewater, and salt water environments. Featuring a robust overload-resistant ceramic measuring cell, climate-proof potted electronics, and optional integrated Pt100 temperature compensation, it delivers high long-term stability across diverse liquid process applications.
Continuous Hydrostatic Level Measurement with Endress+Hauser Waterpilot FMX21
The Endress+Hauser Waterpilot FMX21 is a versatile, high-performance hydrostatic level transmitter engineered for continuous level and temperature evaluation in environmental water monitoring, municipal sewage plants, industrial process vessels, and marine installations. Built with a high-purity ceramic measuring cell and fully potted electronics, the FMX21 maintains uncompromising signal stability even when subjected to mechanical shock, aggressive chemicals, or severe outdoor weather shifts.
Three Specialized Probe Designs for Targeted Applications
To address specific process media and mounting constraints, the Waterpilot FMX21 is available in three distinct probe versions:
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Outer Diameter 22 mm (0.87 in) Stainless Steel: Ideal for narrow drinking water boreholes, deep wells, and small-diameter riser pipes.
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Outer Diameter 42 mm (1.65 in) Stainless Steel: Heavy-duty version featuring a flush-mounted ceramic diaphragm designed for easy cleaning in sticky wastewater, sludge basins, and sewage treatment plants.
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Outer Diameter 29 mm (1.14 in) Plastic Insulation (PPS/Polyolefin): Metal-free process-wetted construction built specifically for corrosive salt water, marine environments, and ship ballast water tanks.
High-Precision Ceramic Cell & Climate-Proof Pressure Compensation
The core of the Waterpilot FMX21 is its high-purity capacitive ceramic measuring cell, providing excellent overload resistance up to 40 bar (600 psi). Barometric pressure fluctuations are automatically neutralized by an integrated 2-filter pressure compensation tube inside the extension cable. The potted sensor body prevents internal condensation, ensuring zero-drift performance in humid or submerged environments.
Simultaneous Level and Temperature Measurement
For applications requiring high-precision volume or density calculations, the FMX21 can be equipped with an optional integrated 4-wire Pt100 resistance thermometer. Paired with HART 6.0 digital communication, the transmitter transmits both level and process temperature data over a single loop, enabling automatic density compensation and comprehensive process control.
Applications
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Drinking Water & Groundwater: Deep boreholes, narrow water wells, clearwater reservoirs, and municipal distribution towers.
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Wastewater & Sewage Treatment: Sludge holding tanks, influent/effluent channels, stormwater retention basins, and digesters.
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Marine & Shipbuilding: Ballast water tanks, bilge water monitoring, and saltwater storage vessels.
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Environmental Monitoring: River gauging, lake water management, flood prevention channels, and dam reservoirs.
Technical Specifications
| Parameter / Feature | Specification Details |
| Measuring Principle | Hydrostatic pressure (Submersible level) |
| Measuring Cell | High-purity capacitive ceramic cell (100 mbar to 20 bar / 1.5 to 300 psi) |
| Probe Configurations | Ø 22 mm (Freshwater/Wells) | Ø 42 mm (Wastewater/Flush) | Ø 29 mm (Saltwater/Plastic) |
| Reference Accuracy | Standard: ±0.2 % | PLATINUM version: ±0.1 % of set span |
| Long-Term Stability | 0.1 % of URL / year |
| Max. Measurement Distance | Up to 200 mH2O (656 ftH2O) |
| Process Temperature | Standard: -10 °C to +70 °C (+14 °F to +158 °F) | Ø 29 mm: 0 °C to +50 °C (+32 °F to +122 °F) |
| Output / Communication | 2-wire 4–20 mA with superimposed HART 6.0 digital signal |
| Supply Voltage | 10.5 to 35 V DC (Non-Ex) / 10.5 to 30 V DC (Ex) |
| Extension Cable Materials | PE (Polyethylene), PUR (Polyurethane), or FEP (Fluorinated Ethylene Propylene) |
| Ingress Protection | IP68 (NEMA 6P) – Continuously submersible |
| Certificates / Approvals | ATEX, FM, CSA, IECEx, NEPSI, Marine (DNV/GL, ABS, BV, LR), Drinking Water (NSF, KTW, ACS) |
FAQ
Q1: What probe diameter options are available for the Waterpilot FMX21?
Answer: The FMX21 is available in 22 mm (for narrow wells), 42 mm (flush diaphragm for wastewater), and 29 mm (plastic-insulated for salt water) probe outer diameters.
Q2: How does the FMX21 compensate for density changes caused by temperature?
Answer: With the optional integrated Pt100 temperature sensor, the FMX21 measures process temperature alongside hydrostatic pressure, allowing connected control systems or HART electronics to perform automatic density correction.
Q3: Can the Waterpilot FMX21 be deployed in marine ballast water tanks?
Answer: Yes, the 29 mm plastic-insulated version is specifically designed for salt water resistance and carries marine certifications from DNV, GL, ABS, BV, and LR.
Q4: What extension cable materials are offered for different chemical exposures?
Answer: Cable options include Polyethylene (PE) for standard water, Polyurethane (PUR) for heavy oil/mechanical stress, and FEP for aggressive chemicals.
Product documents
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