Level switch measurement with Uni-Probe LB 490

The universal field device for various applications

Uni-Probe LB 490 is used for non-contact measurement of level switch and level values. The compact field probe combines detector and evaluation in one device. The level switch measurement is inexpensive, reliable, and accurate and comes with very low source activity.
The level switches Uni-Probe LB 490 has interfaces for HART, Profibus PA and Foundation Fieldbus.
Even if the LB 490 is used in Profibus or Fieldbus systems, it is always possible to switch to HART communication if required. The separate 4-20mA current output can alternatively be used as a signal output (e.g. for a remote display). Relay contacts (DPDT) are available as a binary signal for the level switch.

The robust compact unit for high demands - your advantages at a glance

  • Inexpensive and solid system for standard applications
  • Compact field device with integrated evaluation unit
  • Communication via HART, Foundation Fieldbus or Profibus PA
    (switchable from bus to HART)
  • Communication can be switched over from Bus to HART at any time
  • High operational safety, FMEDA with SFF 96%
  • Many digital and analogue outputs and inputs make the Uni-Probe universally usable

SuperSENS for extreme wall thicknesses

SuperSENS bei großen BehälternLarge containers with extreme wall thicknesses require very high activities. When using the SuperSENS, the source activities can be significantly reduced.
If you already have measurements with point detectors and you are faced with the decision to replace the now weak sources, replacement with a SuperSENS can avoid a replacement of the source, as this will significantly increase the lifetime of the sources.


LB 490
Detector operating data 
Power supply100 ...240 VAC, ±10 %, 50 ... 60 Hz, 15 VA
24 VDC (18 ... 32 VDC), 15 W; 24 VAC +10 %/-15 %, 50 ... 60 Hz, 15 VA
Cabel connections4 cable entries 3/4 inch, NPT, closed with blind plug
Option: metric adapters and cable glands upon request
Maximum cable length3300 m (120 ), 1600 m (250 ), 800 m (500 )
Wire cross-section0.5 ... 1.5 mm2
Housing materialStainless steel ISO 1.4301 / AISI 304
Water coolingOption, max. 6 bar

Scintillator size      Weight   Weight with
Ø x length mm        [kg]       cooling system[kg]  Collimator

(point detectors)

50 x 50 (Nal/TI)        22.5        24                               Standard


150 x 150 (polymer)  52          62                               Standard
Temperature stability≤0,002%/ °C (-40 ... +50 °C) for CrystalSENS bzw.
≤0,01 %/ °C (-40 ... +50°C) for UniSENS
Detector certificates
& tests
IP protectionIP65 / IP66 + Nema 4X
Explosion protection

II 2 GD EEx d IIB T5 IP66 T80 °C          -40 ... +80 °C
II 2 GD EEx d IIC T6 IP66 T80 °C          -40 ... +60 °C
(...+50 °C for LB 490 TowerSENS and SuperSENS)
II 2 GD EEx d [ia] IIC T6 IP66 T80 °C    -20 ... +50 °C 

US/Canada (FM/CSA):
Class I Division 1 Group A, B, C, D      
Class II Division 1 Group E, F, G             -40 ... +50°C

Other certificatesNepsi, IECEx, Kosha, CCOE, others upon request
Signal inputs and outputs 
Signal output

HART 4 ... 20 mA potential-free, active or passive
Max. impedance: 500 Ω (active)
Voltage supply: 12 V ... 24 V (passive)
Max. impedance at 12 V: 250 Ω and/or 24 V: 500 Ω (passive)
Option: intrinsically safe HART current output 4 ... 20 mA, potential-free, passive
Voltage supply: 12 ... 30 V, voltage drop <3,5 V, 20 m signal cable (blue), pre-assembled
Exi IIB: Lo=14.78 mH; Co=679 nF / Exi IIC: Lo=2,18 mH; Co=84 nF

Bus output - option

Bus interface: Profibus PA or Foundation Fieldbus
Bus powered, typical 13 mA with 2xAl function blocks
Option: intrinsically safe Bus interface, 20 m signal cable (blue), pre-assembled
Approval according to ATEX and FISCO

Digital inputsDig In 1: Hold input, Dig In 2: Empty adjustment
Digital outputs

1 relay (SPDT) for collective fault message
3 relays (SPDT) alternatively for : Hold signal, min. / max. alarm,
detector temperature, radiation interference detection
Permissible load at ohmic load: max. 5 A bei 250 VAC or 30 VDC

InterfacesRS 232 for software update
Data backupin non-volatile memory
 For HART, Foundation Fieldbus and Profibus
X-ray interference protection (XIP)
Event log
Continuously monitored current output


Application Report
Format Size
Continuous Level measurement for cement clinker coolers en PDF 754.12 KB
Level Measurement of coke drum level en PDF 694.69 KB
Format Size
Level Measurement Russian language en PDF 2.3 MB
Level Measurement Brochure en PDF 4.85 MB
Product Data Sheet LB 490 en PDF 244.23 KB
Whitepaper Radiometric Measurements Accurarcy, repeatability and errors en PDF 739.65 KB
Format Size
ATEX LB 490-TS, LB 491 SuperSENS en PDF 1.89 MB
CCOE LB 490-TS, LB 491 SuperSENS en PDF 243.11 KB
CCOE Zertifikat LB 49x en PDF 243.11 KB
CSA Zertifikat LB 49x en PDF 383.09 KB
FM LB 490-TS, LB 491 SuperSENS en PDF 244.5 KB
Uni-Probe ATEX Certificat LB49x en PDF 1.63 MB
Uni-Probe FM Certificat LB49x en PDF 63.96 KB
Operation Manual
Format Size
LB 490 Uni-Probe en PDF 31.77 MB
Product Information
Format Size
Level & Density Measurement for -50°C (-58°F) de, en PDF 2.26 MB
Uni-Probe User Interfaces en PPT 511 KB
Project Questionnaire
Format Size
Density en PDF 90.32 KB
Level en PDF 105.49 KB
Level Switch en PDF 109.14 KB
Software Tool
Format Size
LB 490 & LB 491 DTM for HART de, en ZIP 18.78 MB
LB 490 device description for Foundation Fieldbus with capability file de, en ZIP 79.65 KB
LB 490 device description for HART for Siemens Simatic PDM Version 6.0 de, en RAR 41.2 KB
LB 490 device description for HART-communicator de, en ZIP 76.06 KB
LB 490 device description for Profibus PA with GSD file de, en ZIP 95.33 KB
Technical Information
Format Size
LB 490 Uni-Probe de, en PDF 2.86 MB
LB 490 Tower-Sens de, en PDF 9.4 MB