Rosemount 400A Hydrocarbon Analyzer

What a great little machine this is! The Rosemount 400A is a workhorse! Its only downfall is the same as any other THC analyzer … contamination. Call us for parts or service.

Typical failures are:

  • Clogged restrictors (makes it hard to light and/or easy to flame-out)
  • Clogged sample capillary (range switch has to be set lower to compensate for less sample being burned)
  • Burner contact assembly is burned off (noisy display and no response to cal gas)
  • Contamination (zero potentiometer will be very LOW; normal zero pot is > 6.0 turns)
  • Preamp board failed (many symptoms; won’t respond to cal gas or won’t change from high gain to low gain)
  • Thermistor failed (fuel solenoid won’t latch open when ‘purge’ switch is released)

Not so typical failures include:

  • 90 VDC (polarizing voltage) failure (no response to cal gas)
  • ± 12 VDC failed (display won’t be lit)

Here is a Microsoft Excel spreadsheet that will help you calculate the analyzer’s response to various hydrocarbons.   Please call if you need help getting started with this.   Click here to download the calculator:  RIGAS 400A calculations

Pictures: 400A_front_view

Parts (recommended): RIGAS 400A parts list

Manual: Rosemount 400A manual rev L