Features
• Corrosion resistant design
- Housing designed for extreme environments
- Internal construction for extreme samples
- Flow system designed to handle corrosive wet samples
• Sample system designed to handle high humidity
• Accurately measures gases with high levels of H2S present
• 100 ft. sample range
• Up to 4 sensors:
- Methane 0-100% Volume
- CO2 0-50% Volume
- Oxygen 0-25% Volume
- H2S 0-1000 PPM (0-3000 or 0-5000 optional)
• Self draining moisture trap
• Automatic backflush of sampling system
• Long life air aspirator (no moving parts)
• Suitable for inside/outside installations
• NEMA 4X enclosure
• Uses proven RKI technology
• Modular design easy to maintain
• Simple to operate

Industry Applications
• Wastewater Treatment Digesters
• Biogas Methane
• Animal Farms

RKI is proud to introduce our Digester Gas Monitor. Gas from waste digesters
contains high levels of methane, CO2, and H2S, with little to no oxygen
present. The RKI gas monitor checks for all these gases on a cyclic basis.
A powerful air aspirator draws a sample from up to 100 feet away. Since
digester gas contains high humidity and high H2S, both of which can cause
damage to sampling systems, the RKI Digester Gas Monitor is designed to
handle these with no damage to the sampling system or sensors. The sample
is passed through a series of dirt, dust, and moisture stopping filters, and
these filters are automatically purged with fresh air at the end of each cycle.
Measurement time is just 4 minutes, taken at periodic cycles. Cycle time is
selectable, with settings for cycle time of 15 minute, 1 hour, 4 hours, 8 hours,
or 24 hours. A cycle can also be initiated anytime by pressing a button. After
each cycle, the sensors and sampling system are flushed with fresh air so as
to minimize corrosion caused by the high H2S content. The system is fault
tolerant minimizing the possibility of expensive repairs or downtime.
System integrity is maintained at all times using a flow fail monitoring device
which provides a fail alarm and relay if there is ever a problem with the flow
system, such as a blockage, or if the air aspirator compressed air supply is
removed or interrupted.
The system is housed in a wall mounting NEMA 4X enclosure. The gas
readings can be viewed through the enclosure door clear window. Flow meters
and filters are easily visible for confirmation of correct flows and operation.
The RKI Digester Gas Monitor contains adjustable alarm levels for each gas,
and also programmable alarm relays. In addition, the unit provides 4-20mA
signals for each gas concentration for connection to an external DCS, PLC, or
other site control system. A Modbus output is also available. The outputs are
the readings received from the last cycle taken.