D-LX 720

Compact flame monitor with fibre optic system

Application with

Please note that this product was discontinued on December 31st, 2019. Further details are given in the discontinuation letter (English, German). 

Versions with CSA approval can still be purchased.

modernised successor product is available.


  • Wide sensitivity range
  • For ambient temperatures from -40°C up to +85°C
  • Dual channel design throughout
  • Measurement of flame flicker frequency
  • Selective to individual burners and fuels
  • Optionally with complete SIL3 certification
  • Available with cable gland, cable plug (version /MP) or as version for hazardous areas


  • Burners with difficult installation conditions for conventional flame sensors or on those whose ambient temperature near the sighting tube is too high
  • Power stations
  • Chemical industry
  • Refineries
  • Cement plants
  • Waste incinerators
  • Steam generators
  • Heating plants

Technical Data

Operational modeIntermittent operation and continuous operation
SafetySelf-monitoring and fail-safe
Auxiliary supply24 VDC
Flame relay1x NO contact, 24 VDC, 0.5 A
Status relay1x NO contact, 24 VDC, 0.5 A
Flame Failure Detection Time (FFDT)1, 2, 3, 5 s
Analogue output0/4...20 mA
Spectral rangesUV, IR
Threshold switchesFlame intensity and flicker frequency
CommunicationLED, Modbus RTU, IrDA
Ambient temperature range-40...+85°C
Protection classIP66/68
IP65 for version /MP
Dimensions85 x 85 mm, length approx. 175 mm
Weightapprox. 1.25 kg
Ex protection
D-LX 720 ../85ExCl. I, Div. 1, Gr. A, B, C, D T6/T5
Cl. II, Div. 1, Gr. E, F, G T6/T5; Class III
Type 4
Hazardous locations: indoor/outdoor
D-LX 720 ../86ExCl. I, Div. 2, Gr. A, B, C, D T6/T4
Cl. II, Div. 2, Gr. E, F, G T6/T4; Class III
Type 4
Hazardous locations: indoor/outdoor
Max. ambient temperature+85°C (/85Ex)
+65°C (/86Ex)
Protection classIP66
DimensionsØ120 mm, length approx. 230 mm
Weightapprox. 3.2 kg


  • LED bar graph display for the flame intensity (D-ZS 129)
  • Terminal box for connecting the flame monitor (D-ZS 140-12)
  • Installation flange for D-LL 703 fibre optic system (D-ZS 703)
  • Welding flange for D-LL 704 fibre optic system (D-ZS 704)
  • Wide range power supply unit for supply of several D‑LX 720 (D-NG 24/25a)
  • D-LX 200 Test kit for software supported tests of the compact flame monitors D-LX 200/720

Варианты связи с Вами