Programmable level controller Lev 7

with LCD displaywith alarm functionwith relay output

Overview
The Lev 7 glass level control unit measures and controls molten glass level in furnaces using a mechanical crank-rod drive and a platinum/rhodium sensing tip. Precise level control reduces batch charger speed fluctuations and carryover, stabilizes gas/fuel flow and furnace temperature profiles, lowers energy consumption and improves glass quality and production efficiency.

Benefits

• Reduces batch charger speed fluctuations
• Minimises carryover
• Stabilises gas and fuel flow
• Maintains consistent furnace temperature patterns
• Lowers energy consumption
• Improves glass quality
• Increases production efficiency

Machine composition

• Glass level control unit (Lev 7)
• Probe (side water-cooled or top alumina)
• Control board with touch-screen PLC
• Connecting cables (optional)
• Cooling fan
• Cooling water flow and temperature control system (for water-cooled probe only)

Probe configurations supported

• 1) Side wall installation – stainless steel single-pipe, water-cooled probe with platinum/rhodium tip
• 2) Top installation – vertical alumina probe with platinum/rhodium tip

Measurement principle and operation
The glass level is detected when the platinum/rhodium sensor tip contacts the molten surface and closes the detection circuit. To avoid adhesion of glass particles the unit can apply a high-current electrical impulse via a dedicated transformer. The probe is driven by a robust crank-rod mechanism with two approach speeds; approach speed is reduced for final detection. A high-precision optical encoder directly measures crank position and the PLC calculates vertical stroke. Touch parameters (speed, frequency, recession speed) are programmable from the touch-screen PLC.

Automatic reactions on glass detection

• Immediate retract of the probe at high speed
• Electrical impulse generation to clean the probe tip (via high-voltage transformer)

Outputs & integration

• Two programmable analog outputs (4–20 mA) proportional to measured level and set point
• Digital ON/OFF output contact to drive a batch charger (Lev 7 can control a batch charger via PID loop or ON/OFF)
• Data/display integration with PLC/DCS; Modbus/Ethernet optional

Controls & programmability

• Touch-screen LCD for parameter setup and process overview
• Programmable measuring cycle, approach and measuring speeds
• Programmable electrical impulse timing to prevent sticking
• Alarm messages on screen, programmable high/low level alarms with relay outputs, horn and status lights (RED-GREEN-YELLOW)

New features

• Mechanical handle for vertical probe position regulation: max stroke 100 mm, position indicator resolution ±1 mm
• Internal ball-bearing autorotation for probe
• Vertical shaft movement on ball bearings
• Quick-change mechanism for easy probe removal
• Standardised connectors for simplified cabling and machine connection

Main features (other options available on request)

• Auto-zero detection
• Automatic glass level calibration
• Level set point programmable from touch-screen with process overview
• Asynchronous servo-cooled motor driven by vector inverter, direct gear coupling (no belts/chains)
• Vertical movement via crank-rod with ball bearings
• Resolution: ±0.1 mm
• Repeatability: ±0.1 mm
• Maximum vertical stroke (measurement): 40 mm
• Encoder removable/excludable in case of fault
• Dedicated transformer for electric impulse to avoid glass sticking

Side wall configuration – probe & cooling details

• Water-cooled side probe: single-pipe stainless steel with platinum/rhodium tip Ø 3 mm x 15 mm, total length 1600 mm. Requires side slot in forehearth or distributor.
• Cooling water flow: 20 litres/min
• Max cooling water input temperature: 35°C
• Max cooling water output temperature: 45°C
• Water cooling pressure range: 2–4 bar
• Water quality: chloride ≤ 50 ppm, pH 8.0–8.5, calcium ≤ 40 ppm

Top installation – probe details

• Vertical alumina probe 799 with platinum/rhodium tip Pt Ø 2 mm x 15 mm
• Probe total length: 1000 mm plus DIN-type connector head

Notes on reliability & operation
Lev 7 is designed for continuous 24/7 operation in high-temperature furnace environments. The system is engineered for easy maintenance and user-friendly operation; all key parameters are set via the touch-screen display.

Technical specifications

• Model name: Lev 7
• Measurement resolution: ±0.1 mm
• Repeatability: ±0.1 mm
• Maximum vertical stroke (measurement): 40 mm
• Probe types: water-cooled metal probe (side) or vertical alumina probe (top)
• Side probe tip: platinum/rhodium Ø 3 mm x 15 mm, probe length 1600 mm
• Top probe tip: platinum/rhodium Ø 2 mm x 15 mm, probe length 1000 mm
• Cooling water flow (side probe): 20 litres/min
• Cooling water temperature input max: 35°C; output max: 45°C
• Cooling water pressure range: 2–4 bar
• Water quality: chloride ≤ 50 ppm, pH 8.0–8.5, calcium ≤ 40 ppm
• Movement: asynchronous servo-cooled motor with vector inverter, direct gear coupling
• Vertical motion mechanism: crank-rod with ball bearings
• Encoder: high-precision optical encoder (can be excluded in case of fault)
• Electrical supply (example): 0.34 kW, 220 VAC, 50 Hz
• Outputs: 2 programmable 4–20 mA outputs; ON/OFF output contact; alarm relay outputs
• Integration: direct batch charger drive (PID or ON/OFF); display to PLC/DCS; Modbus/Ethernet optional