OHC-800 Explosion-Proof Gas Calorimeter | RKI

OHC-800 Explosion-Proof Gas Calorimeter

  • Unique measuring principle ”Opt-Sonic calculation” is applied. This can minimize the interference effects caused by interferencegases, and a high-accuracy measuring result can be obtained.
  • Fast response time T90 reaction within 5 seconds.
  • High repeatability +/- 0.02MJ/㎥
  • Wide operation temperature -20 ~ +57 degree C
  • Explosion-Proof structure even for Hydrogen Exd IIB+H2 T4
  • High ingress protection level IP66 / IP67
  • Remarkable temperature characteristic, below 0.10MJ/㎥ fluctuation for the temperature change in a day (< 20 degree C)
  • Easy to switch the display among “Calorific value”, “Density” and “WOBBE index” just by the button operation.
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All in one explosion-proof gas calorimeter which features high accuracy, continuous measurement and high-speed response.

Opt-Sonic calculation” is applied by using Optical sensor and Sonic sensor
“Opt-Sonic calculation” is based on the calculation combining 2 measuring results obtained by the 2 sensors. This can minimize the interference effects on the reading caused by interference gases, and enable the high-accuracy and reliable measurement. * Opt-Sonic is a term coined by RIKEN KEIKI to describe Optical and Sonic sensors

Easy to switch the display among “Calorific value”, “Density” and “WOBBE index”
Displayed unit is easily switched by pressing the button. Laborious calculation is not needed.

Fulfilling self-diagnosis function and running cost
Self-diagnosis function including fault diagnostic prevents the calorimeter from being incapable of measuring the gas. Few consumables are needed and this saves running cost.

Body structure that can be installed into all types of location
Structure is robust with Explosion-Proof (Exd IIB+H2 T4) and high ingress protection level (IP66/IP67) Both 100VAC~240VAC and 24VDC power supply can be supplied.



  • Natural gas
  • Steel gases (COG,BFG,LDG)
  • LPG
  • Natural gas with Hydrogen
  • Flare gas
  • Methane
  • Natural gas with LPG
  • Boil-off gas
  • E-methane
  • Renewable natural gas
  • Off-gas from refinery
  • Butane
  • Biogas
  • Methanation gas
  • Low calorie gases, and so on
  • Biogas with LPG
  • Hydrogen


Model OHC-800
Measuring principle Opt-Sonic calculation through measurement of refractive index and sound speed
Measuring gas CH4 basis Paraffinic Hydrocarbon gases as represented by Natural Gas *1
Measuring targets Calorific value (Density / WOBBE index selectable)
Measuring range *2 Calorific value : 25.00~50.00 MJ/㎥ (Gross, 0 degree C, 101.325kPa converted)
Density : 0.500~1.500 MJ/㎥ (Specific gravity converted)
Measuring method Constant-flow-rate gas introduction using external sampling devices
Display Full-dot LCD (with backlight), 3 color LED lamp
External Output 4-20 mA DC (isolated, source current type) maximum load resistance of 300 Ω / RS-485 communication
FAILURE alarm Low flow, Sensor unit abnormality, Low light amount
FAILURE alarm display Lamp (red) / Content indication on LCD
FAILURE alarm contact *3 No-voltage contact 1a or 1b De-energize (Energize when alarming) or Energize (De-energize when alarming)
Contact capacity of 2 A, 30 VDC (resistance load)
Self-diagnostic function FUNCTION CHECK (warm-up or maintenance mode), MAINTENANCE REQUIRED, OUT OF SPECIFICATION
Self-diagnostic display FUNCTION CHECK, OUT OF SPECIFICATION : Lamp (orange) / Content indication on LCD
MAINTENANCE REQUIRED : Lamp (green) / Content indication on LCD
Self-diagnostic contact FUNCTION CHECK, OUT OF SPECIFICATION : No-voltage contact 1a or 1b De-energize (Energize when alarming) or
Energize (De-energize when alarming) Contact capacity of 2 A, 30 VDC (resistance load)
MAINTENANCE REQUIRED : SSR contact, contact capacity of 20 W, 240 VAC (resistance load)
Power supply 100 – 240 VAC ±10%, 50/60 Hz, max. 18 VA or 24 VDC ±10%, max.
5 W (The setting can be changed to either the AC or DC)
Ingress Protection level Equivalent to IP66 and IP67
Operation temperature -20~+57 degree C(TIIS)/-20~+60 degree C(ATEX/IECEx)
Operation humidity 95%RH or less (no condensing)
Outer dimensions / Weight Approx. 286 (W) x 453 (H) x 150 (D) mm / Approx. 23 kg
Explosion-Proof structure Flame-proof enclosures (Explosion-proof class: ExdⅡB+H2 T4 <TIIS>/Ⅱ2GExdⅡB+H2T4 <ATEX/IECEx>)
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