RHADOX 7300 / 7300 Ex

Besides the measuring values Wobbe-Index and Air demand, the RHADOX 7300 / 7300 Ex Analyser measures Gas density and Heat value.

The determination of the Gas density is performed according to the method of Bernoulli (1730) who was using the dependency of a laminar gas stream through an orifice. Since temperature and pressure of the sample gas and the air are already levelled in the RHADOX™ mixing chamber, the ratio of the flow of both components in a second mixing chamber is used to measure the Specific Gravity. A reference measurement of ambient pressure and temperature at the location of the  RHADOX™ analyser compensates the ambient influence. The result is a precise measurement of the Gas density.

The readings of Wobbe-Index and Gas density allow the calculation of the Heat value.


The RHADOX™ determines the measuring components Wobbe-Index and Air demand by measuring the residual oxygen after the oxidation. To achieve highly accurate measuring values, the parameters pressure and temperature have to be constant within low limits. By way of construction this is achieved with:

  • A control unit to level the pressure of the Off-gas and Air
  • A heat exchanger to level the temperature of the Off-gas and Air
  • The patented mixing chamber and the also patented method of the catalytic oxidation.



Technical data

Measuring System RHADOX 7300 / 7300 Ex
Ex-classification ATEX II 2G Ex px IIB+H2 T4 Gb X (Ex-Zone 1)
ATEX II 3G IIB+H2 T3 (Ex-Zone 2)
Measuring components / -ranges  
Air demand smallest measuring span 1,5 m3 Air / m3 Gas
largest measuring span 30 m3 Air / m3 Gas
Wobbe-Index smallest measuring span 5 MJ / m3
largest measuring span 120 MJ / m3
Specific gravity
(gas density relative to air)
smallest measuring span 0,5
largest measuring span 30
Calorific value smallest measuring span 5 MJ / m3
largest measuring span 140 MJ / m3
Analogue signal port 4* 4 … 20 mA, galvanically separated
Air Demand & Wobbe-Index 0,15 % - 0,2 % of the measuring value
spec. Gravity and Cal. Value 1,0 % - 2,0 % of the measuring value
Long term drift < 2 % of measuring value / Month
Temperature drift < 0,02 % / K, relative to end of measuring range
T90-Time  5…15 seconds, depending on viscosity of the measuring gas
Other data  
Display 2* 16 digit illuminated LCD display
showing measuring values and system parameters
Option graphic display
Messages 1 System message (Measuring value yes / no)
3 Messages (Indication of operating status)
Service, Calibration, Error messages
Digital Communication serial Interface RS232
Option Interface RS485 or Ethernet
Ambient operating temperature from - 5 °C to + 45 °C
Operating temperature from + 5 °C to + 60 °C
Special version up to + 105 °C
Gas connections  
Inlet 6 mm Ferrule pack
Outlet 12 mm Ferrule pack
Gas flow volume Measuring gas 20 … 100 Nl/h
Instrument Air 50 … 500 Nl/h (depending on Air demand)
Gas presse (at Inlet) Gas > 0,1 bar (g), max. 17 bar (g)
Iinstrument air > 2 bar (g), max. 8 bar (g)
Power supply 115 or 230 VAC / 50 - 60 Hz, 1000 VA
Protection class / Housing IP65
Dimensions 1000 x 900 x 350 mm (hxbxt)
Weight approx. 100… 155 kg depending on options and protection class
Options Integrated catalytic remover of by-pass gas
Version: AMS RH7300 E V-2013-07