• Repeatability: ±1 mm
  • pmax : 650 PSIG
  • tmax : 265 °F,300 °F (for CIP Process)
  • Connections:NPT, Flange, Hygienic
  • Material:316L Stainless Steel
  • Viscosity:Max. 5000 cSt
  • No Moving Parts
  • ATEX / IECEx Version


liquid level switch NWS is designed as a 2 and 3-wire switch and can be universally used in tanks and pipelines. The NWS operates on the tuning fork principle in air at resonance frequency. A piezoelectric crystal is used for excitation of oscillations and for monitoring the actual oscillation frequency. When the fork is immersed in liquid, the frequency changes: this change is detected electronically and the output signal is changed. The NWS operates as a 2-wire switch in series with the load. The simple electronic switch is operated by the liquid. The NWS can also be connected to a PLC through a third terminal. The NWS has an output state indicator with an LED that can be seen though a lens in the cover. The LED flashes about once a second when the NWS has switched off and is permanently illuminated when the NWS is switched on. The LED is an optical confirmation that the NWS is working correctly and the condition of the wet side is correctly displayed. The NWS can be set as upper or lower limiter with a mode selector.


  • Oils and Foamed Olis
  • Water
  • Paints and Transparent Inks
  • Sauces
  • Milk
  • Liquids Containing Carbon Dioxide
  • Hygienic and Sterile Applications
  • CIP Cycles up to 300 °F.

ATEX / IECEx Version:

  • Type of Protection: Intrinsically Safe ia
  • Designation: II 1G Exia IIC T6 Ga IECEx Exia IIC T6 Ga
  • For Use in Connection with Intrinsically Safe Isolation Switching Amplifier According to IEC 60947-5-6



Technical Data

Fork: 316L Stainless Steel
Connection: 316L Stainless Steel
NWS-.. 200: PAG, Fiberglass-reinforced Cover with Window, 330° Rotatable
All Other Types: 304 Stainless Steel
Connections: NPT-thread, Tri-Clamp®,
Sanitary Connection,
Flange ANSI B 16.5 - 1", 300 lbs,
Flange ANSI B 16.5 - 2", 300 lbs

Plastic Housing: 
IP 65 (NWS-.. 200)
SS Housing/
Plug Connection: 
IP 67
SS Housing/
Cable Connection: 
IP 68
Max. Operating
650 PSIG Flange Connection: See Pressure Steps
Max. Media Temp.: 265 °F (NWS-.. 200..) 194 °F (for all other NWS) Short-time 300 °F for CIP (Valid for all Models NWS)
Min. Media Density: 800 g/l (lower densitys on request)

Ambient Temperature: -4... 158 °F
Min. Immersion Depth
for Switch Points: 
0.48" (Marker on Fork)
Power Supply
NWS-.. 200..: 
24... 240 VDC/AC (50/60 Hz); 2-wire; 24 VDC, 3-wire
Leakage Current in
Off State: 
< 3.5 mA
NWS-.. 23/24/2W/
2H .. : 
24 VDC, 3-wire
NWS-.. 2E .. (ATEX): Isolation Switching Amplifier to IEC 60947-5-6 (Namur) Necessary (for example: KFD2-SR2-EX1.W or KFA6-SR2-EX1.W)
Delay: 1 s wet /dry
1 s dry / wet
Viscosity: 5000 cSt max. at 77 °F
(Influence on the Response Time)
Hysteresis:4 mm Vertical, 1 mm Horizontal
Repeatability:± 1 mm
Weight:1.1 lb (¾" NPT)


Electrical Connection

Wiring Diagram

Wiring Examples NWS-.. 2E.. with Power Supply Unit acc. to IEC 60947-5-6

Order Details (Example: NWS-N20 200 0070)