Endress+Hauser Liquiphant FTL51 Vibronic Point Level Switch
Overview of the Endress+Hauser Liquiphant FTL51
The Endress+Hauser Liquiphant FTL51 is a vibronic point level switch for maximum or minimum detection of all kinds of liquids in tanks, vessels and pipes. It belongs to the Liquiphant M family described in Technical Information TI00328F, and differs from the compact FTL50 by its extension pipe, which places the tuning fork at the required switch point up to 3 m (9.8 ft) below the process connection, or up to 6 m (20 ft) on request. The sensor works from –50 to +150 °C, withstands process pressures up to 100 bar and is recommended for safety systems up to SIL2/SIL3 according to IEC 61508 and IEC 61511.
Seven Star LLC supplies the Endress+Hauser Liquiphant FTL51 to refineries, tank farms, chemical plants and water facilities across the Sultanate of Oman and the GCC, with engineering support in Muscat. Endress+Hauser now lists the Liquiphant FTL51B as the successor generation, and Seven Star LLC can quote the FTL51 for like-for-like replacement or advise on the newer design where a project allows it.
Operating Principle of the Endress+Hauser Liquiphant FTL51
The Endress+Hauser Liquiphant FTL51 uses a tuning fork that is excited to vibrate at its intrinsic frequency. When the fork is covered by liquid, the frequency drops, and the electronic insert evaluates this change and switches the output. Because the measurement is based on frequency rather than on buoyancy or conductivity, the switch is not affected by flow, turbulence, gas bubbles, foam, vibration, solids content or buildup, which makes it a reliable substitute for float switches.
Under reference conditions the switch point is reproducible to 0.1 mm, the maximum measured error is ±1 mm and the hysteresis is about 2 mm. The influence of medium temperature over the full –50 to +150 °C range is within +1.8 to –2.8 mm, and the density setting on the electronic insert can be changed between 0.7 g/cm³ (delivery status) and 0.5 g/cm³. Switching delay is 0.5 s when the fork is covered and 1.0 s when it is exposed, with other values available on request. There are no mechanically moving parts, so no adjustment, wear or routine maintenance is needed.
Engineering Design of the Endress+Hauser Liquiphant FTL51
Wetted parts are made of 316L stainless steel (1.4404 or 1.4435), with Alloy C22 (2.4602) available for the process connection, extension pipe and fork when corrosive media are involved. Process connections include G ¾ and G 1 threads, NPT ¾ and NPT 1, R ¾ and R 1, and EN, ASME and JIS flanges, and the extension pipe of 21.5 mm diameter can be ordered in any length from 117 mm to 3000 mm. A temperature spacer or pressure-tight feedthrough can be added between process and housing.
The housing is chosen to suit the site: polyester F16, stainless steel F15, aluminium F17, stainless steel F27, or aluminium F13 and T13 for Ex d and Ex de applications, with degrees of protection up to IP66/IP68 and NEMA 4X/6P depending on the version. The Endress+Hauser Liquiphant FTL51 accepts plug-in electronic inserts: FEL51 two-wire AC (19 to 253 V), FEL52 three-wire DC PNP (10 to 55 V), FEL54 universal current with two floating change-over contacts, FEL55 16/8 mA, FEL56 and FEL58 NAMUR, FEL57 PFM, and FEL50A for PROFIBUS PA.
Key Features of the Endress+Hauser Liquiphant FTL51
The points below, from TI00328F, summarise why the Endress+Hauser Liquiphant FTL51 is widely specified for liquid limit detection:
- Extension pipe from 117 mm to 3000 mm, with 6000 mm available as a special version, to set the switch point exactly where it is required.
- Process temperature from –50 to +150 °C and process pressure up to 64 bar as standard or 100 bar with the corresponding option.
- Works with liquids of density from 0.5 g/cm³ and viscosity up to 10,000 mm²/s, and tolerates solids up to ø5 mm.
- Recommended for safety instrumented functions to SIL2/SIL3, with monitoring of the tuning fork for damage.
- Design in accordance with ASME B31.3 and a single-seal design to ANSI/ISA 12.27.01 for CSA and FM.
- Hazardous area versions with ATEX and IECEx Ex d and Ex de approvals, plus NEPSI safety instructions.
- Seven electronic inserts plus PROFIBUS PA, so the same sensor can switch a load directly, drive a PLC input or report to a separate switching unit.
- Pipe installation from 2 in with flow velocities up to 5 m/s for water-like liquids, and a lateral loading capacity of 75 Nm.
Industrial Applications of the Endress+Hauser Liquiphant FTL51
Typical duties for the Endress+Hauser Liquiphant FTL51 are overfill protection on fuel and chemical storage tanks, dry-run protection for pumps, high and low alarms in process vessels and day tanks, and limit detection in pipes and sumps. The extension pipe lets one model cover high-level alarms close to the roof and low-level alarms deep inside a tank, while the Ex d housings suit refinery, gas plant and terminal service. In Oman this applies to fuel depots and terminals, oil and gas processing facilities in the interior, chemical plants in the Sohar and Salalah free zones, and desalination and water treatment chemical tanks.
Seven Star LLC supplies the Liquiphant switches alongside continuous level devices, so one enquiry can cover both the limit switch and the level transmitter for a tank. Buyers can pair the switch with the Endress+Hauser Micropilot FMR20 radar or the Levelflex FMP51 guided radar for continuous level, or with the Cerabar PMC71B pressure transmitter for hydrostatic measurement.
Technical Specifications of the Endress+Hauser Liquiphant FTL51
The table lists key data of the Endress+Hauser Liquiphant FTL51 taken from Technical Information TI00328F.
| Parameter | Specification |
|---|---|
| Model | Liquiphant M FTL51 (with extension pipe) |
| Measuring principle | Vibronic tuning fork, point level detection |
| Extension pipe length | 117 to 3000 mm; up to 6000 mm on request |
| Process temperature | –50 to +150 °C |
| Process pressure | –1 to 64 bar; 100 bar option |
| Medium density | > 0.7 g/cm³ (delivery status) or > 0.5 g/cm³ |
| Viscosity | Up to 10,000 mm²/s |
| Repeatability / hysteresis | 0.1 mm / approx. 2 mm |
| Switching delay | 0.5 s covered, 1.0 s exposed |
| Wetted materials | 316L (1.4404/1.4435); Alloy C22 optional |
| Process connections | G ¾, G 1, NPT ¾, NPT 1, R ¾, R 1; EN, ASME, JIS flanges |
| Electronic inserts | FEL51, FEL52, FEL54, FEL55, FEL56, FEL57, FEL58, FEL50A |
| Functional safety | SIL2/SIL3 per IEC 61508 / IEC 61511 |
| Storage temperature | –50 to +80 °C |
How to Order
To order the Endress+Hauser Liquiphant FTL51, send Seven Star LLC the medium, density, process pressure and temperature, required pipe length, process connection, housing and electronic insert, and our instrumentation division will return a formal quotation with lead time. The Technical Information TI00328F can be downloaded from this page. Seven Star LLC is a trusted supplier of Endress+Hauser level switches in Oman and the GCC, with engineering support in Muscat for selection and commissioning.
- Datasheet Endress+Hauser Liquiphant M FTL50/FTL51 Technical Information (TI00328F) Download
Reviews
There are no reviews yet.