TDR-guided wave radar level transmitter NGM series

for solidsfor oilfor liquids

Overview The NGM uses TDR (Time Domain Reflectometry), also called Guided Wave Radar. Low-energy, high-frequency pulses travel along a probe immersed in the measured liquid or light solid. Reflected energy from the media surface is detected and converted into a level measurement. Outputs include 4 … 20 mA analogue and freely programmable switching outputs; HART® configuration is available.

Highlights

• Suitable for liquids and light solids
• Unaffected by density, temperature, pressure, humidity or conductivity
• Measuring length up to 20 m (depending on probe)
• 4 … 20 mA analogue output; HART® configurable
• Programmable limit-switch outputs
• Ingress protection IP68

Applications NGM provides direct, continuous level measurement and point-level detection in a wide range of process conditions. It is suitable for small tanks, tall narrow nozzles, bypass chambers and stilling wells and performs reliably with difficult tank geometries and near internal structures. Effective for media with low dielectric constant such as oils and hydrocarbons.

Technical data (excerpt) Measuring principle: Guided Wave Radar (TDR)
Mounting position: vertical
Ambient temperature: -25 … +80 °C
Storage temperature: -40 … +85 °C
Max. pressure: -1 … +40 bar (except NGM-19: 0 … 4 bar)
Accuracy*: ±3 mm or 0.03 % of measured distance (higher value applies)
Repeatability*: < 2 mm
Resolution*: < 1 mm
Velocity of level change: < 1000 mm/s
Process connection: thread or flange (see ordering code)
Housing material: aluminium alloy, epoxy coated (option: stainless steel 1.4401/SS316)
O-ring options: FKM, EPDM, NBR or none depending on probe and version
Electrical: Supply 12 … 30 VDC (4-wire, reverse-polarity protected); Output 4 … 20 mA (HART®); Response time: 0.5 s (default), selectable 2 s or 5 s
Switching output: DC PNP (active) NC [standard] or NO; Load current < 200 mA; Switching response < 100 ms
Cable entry: 2 x M20 x 1.5
Ingress protection: IP68

Probe data

• Rod probe — diameter: 6 mm; length: 100 … 3 000 mm; dielectric constant εr > 1.8; medium temp (standard): -40 … +150 °C (PTFE variants as specified)
• Wire rope — diameter: 4 mm; length: 1 000 … 20 000 mm; tensile load: up to 5 kN; εr > 1.8; medium temp: -40 … +150 °C
• Coax — diameter: 17.2 mm; length: 100 … 6 000 mm (standard) or 100 … 1 000 mm (high temp); εr > 1.4; viscosity limit < 500 cP; medium temp variants up to +250 °C depending on O-ring

Approvals ATEX and related explosion-protection classifications available (examples: CE 0158 SEV 13 ATEX 0108 X).

Key specifications

• Model / Type: NGM
• Measuring principle: Guided Wave Radar (TDR)
• Measuring range: up to 20 m (depending on probe)
• Outputs: 4 … 20 mA analogue; programmable switching outputs; HART® configurable
• Supply: 12 … 30 VDC (4-wire)
• Ingress protection: IP68
• Probe options: rod, wire rope, coaxial
• Materials: aluminium or stainless steel housing; PEEK, PTFE and stainless steels for wetted parts
• Operating temperature (ambient): -25 … +80 °C
• Accuracy / repeatability: ±3 mm or 0.03 %; repeatability < 2 mm
• Certifications: ATEX options