MOLOSbob LF20 Yo-Yo Type Continuous Level Measurement (Tape-Type Plumb Bob)

The MOLOSbob LF20 is a highly reliable yo-yo (tape-type) continuous level measuring system from Mollet for bulk solids in silos and vessels up to 42 m height. It delivers precise fill level and (optional) interface measurement completely independent of material properties. The device provides a 4–20 mA analog output and supports visualization via display units. The LF20-T version is specially designed for interface measurement.

Operating Principle

The yo-yo sensing system lowers a sensing weight attached to a stainless-steel tape into the silo. Tape speed during descent and ascent is 0.16…0.25 m/s with a maximum pulling force of 150 N. The measured distance travelled by the weight is converted into a precise 4–20 mA signal. All settings are made via a user-friendly menu on the built-in text display.

General Specifications – MOLOSbob LF20

• Materials: Housing – powder-coated aluminium (RAL 7001) or bare; Tape wiper – aluminium/steel or stainless steel (304); Measuring tape – modified stainless steel (301); Process connection – DN100 PN16 / 4" aluminium flange

• Certifications: ATEX Dust II 1/2D IIIC (suitable for dust explosion zones)

• Temperature: Ambient –40…+60 °C; Process –20…+150 °C

• Pressure: –0.5…+1.0 bar

• Measuring range: 0…42 m

• Power supply: 90…253 V AC 50/60 Hz or 20…28 V DC

• Power consumption: Max. 150 VA without heater; max. 170 VA with optional heater

• Output signals: Active 4–20 mA current output; Up to 4 programmable relay outputs max. 250 V AC / 6 A; Optional opto-isolator max. 30 V DC / 10 mA

• Mounting: Dimensions 300 × 260 × 225 mm (H × W × D); Weight 11.5 kg incl. weight; Flange DN100 PN16 / 4" aluminium; Max. roof inclination 2°

• Protection: IP67 / IP66 according to EN 60529; Integrated tape wiper prevents contamination; Safety catch prevents accidental dropping into the silo outlet

Main Application Areas

Continuous level and interface measurement of bulk solids (including dusty and non-conductive materials) in silos and vessels up to 42 m height and process temperatures up to +150 °C.

Advantages of the MOLOSbob LF20 Yo-Yo Level Measuring System

• Completely independent of bulk material properties (dust, conductivity, dielectric constant)

• High measuring accuracy (±2.5 cm)

• No complicated parameter setting required

• Approved for dust explosion hazard zones (category 1/2D)

• Compact, robust and lightweight design

• Easy menu-guided operation with text display

• Safety catch prevents unintended dropping of the weight into the silo outlet

• Very low maintenance and long service life