An external charcoal filter may also be used in series with the external water filter and should be installed on the instrument side of the external water trap filter. The charcoal filter is used when known or suspected levels of H2S, hexane, propane, or other non-methane hydrocarbons exceeding one hundred ppm. Presence of these gases can affect the methane channel by indicating artificially high concentrations of methane. The charcoal filter needs to be condition with Calibration gas before use.
The GEM Temperature Probe can be hooked into the communcation socket to display temperature readings on gas reading screen. The temperature reading data can be recorded with all other data.