Tuning fork level switch NWS series

for waterfor oilfor liquids

Highlights

• Measuring length up to 4000 mm
• Level indicator in percent and 4-20 mA analogue output (where applicable)
• 2- and 3-wire switch versions; four device variants for different applications
• ATEX/IECEx certified options

Description
The KOBOLD liquid level switch NWS operates on the tuning-fork (resonance frequency) principle. A piezoelectric crystal excites and monitors the fork oscillation. When the fork is immersed in liquid the resonance frequency changes; this change is detected electronically and converted into a switch signal. The device is available as a 2‑wire switch (in series with the load) or as a 3‑wire version for direct PLC connection.

Applications

• Oils and foamed oils
• Water
• Coatings, paints and clear inks
• Food products such as sauces and milk
• Carbonated liquids

Hygiene and CIP
The NWS is suitable for hygienic and sterile environments and supports short-term CIP cycles up to 150 °C, making it suitable for food, beverage and pharmaceutical processes.

Technical data

• Type: NWS
• Measuring principle: tuning fork (resonance frequency) with piezoelectric excitation and frequency monitoring
• Material:
  • Fork: stainless steel 1.4404
  • Process connection: stainless steel 1.4404
  • Electronic housing: NWS-…200: PAG with glass-fibre-reinforced cover and window, 330° rotatable; other types: stainless steel 1.4301
• Process connections:
  • pipe thread DIN EN 10226-1
  • NPT thread
  • Tri-Clamp®
  • pipe connection DIN 11851 (sanitary)
  • aseptic connection DIN 11864
  • DRD flange
  • Flange B 25 PN 40 DIN 2527
  • Flange B 50 PN 40 DIN 2527
  • Flange ANSI B 16.5 – 1", 300 lbs
  • Flange ANSI B 16.5 – 2", 300 lbs
• Ingress protection:
  • plastic housing: IP 65 (NWS-…200)
  • stainless steel housing: plug connection IP 67; cable connection IP 68
• Max. operating pressure: 45 bar (flange dependent)
• Medium temperature:
  • -20 … 130 °C (NWS-…200…)
  • -20 … 90 °C (other NWS)
  • short-time 150 °C for CIP (all models)
• Minimum medium density: 800 g/l
• Ambient temperature: -20 … +70 °C
• Minimum immersion depth for switch points: 12 mm (marker on fork)
• Power supply:
  • NWS-…200: 240 V DC/AC (50/60 Hz), 2-wire; 24 V DC, 3-wire
  • NWS-…23/24: 24 V DC, 3-wire
  • NWS-…2E… (ATEX): requires intrinsically safe isolation switching amplifier according to IEC 60947-5-6
• Delay: 1 s wet/dry; 1 s dry/wet
• Viscosity: up to 5000 mm²/s at 25 °C (affects response time)
• Hysteresis: 4 mm vertical, 1 mm horizontal
• Repeatability: ±1 mm
• ATEX / IECEx:
  • Type of protection: intrinsically safe ia
  • Designation: Ex II 1G Exia IIC T6 Ga; IECEx Exia IIC T6 Ga

Specifications

• Model: NWS
• Brand: KOBOLD
• Measuring length: up to 4000 mm
• Outputs: switch (2-wire or 3-wire); optional level indicator in percent with 4-20 mA
• Measuring principle: tuning fork with piezoelectric excitation and frequency monitoring
• Fork material: stainless steel 1.4404
• Electronic housing: PAG with glass-fibre-reinforced cover (NWS-…200) or stainless steel 1.4301
• Ingress protection: IP 65 / IP 67 / IP 68 depending on housing and connection
• Operating pressure: up to 45 bar
• Medium temperature range: up to 130 °C (model dependent); short-time 150 °C for CIP
• Minimum medium density: 800 g/l
• Switching delay: 1 s
• Hysteresis / repeatability: 4 mm vertical / 1 mm horizontal; repeatability ±1 mm
• ATEX/IECEx options available