Continuous Emissions Monitoring Systems (CEMS) From A-Z: A Multi-Part Series - Extractive CEMS Umbilical (Part 3)


Continuous Emissions Monitoring Systems (CEMS) From A-Z: A Multi-Part Series - Extractive CEMS Umbilical (Part 3)

This issue continues our presentation of a comprehensive look at Continuous Emissions Monitoring Systems (CEMS) from beginning to end, with descriptions and details on a variety of components including the probe, umbilical, sample conditioning system, analyzers and more - including maintenance and troubleshooting topics.

This issue covers: Extractive CEMS Umbilical

The umbilical is a bundle of pneumatic tubes and electrical wires used to interconnect the probe, the gas analyzers, and gas transport system.  The typical umbilical requires 220VAC power.


Wiring - The umbilical system includes the control wiring for the stack J-box and the AC voltage for the probe and umbilical heaters. (typically 115V and 24V respectively)

Tubing - Typically, the umbilical only has the tubes listed below, but it is possible to add a spare tube.  If more than one spare is desired, it may become difficult to keep the entire umbilical rated for above 80˚F.

  1. One 3/8" PFA Teflon tube for transportation calibration gas to the probe. 
  2. One 3/8" Teflon tube for transportation sample CEMS.
  3. One 3/8" PFA Teflon for transporting instrument and purge air to the probe.

Insulation/Jacket - The tube/wire bundle is wrapped in an aluminized,  Mylar thermal barrier and is surrounded with Aspen Aerogel which has 4 times better insulating properties than fiberglass, and allows the umbilical to be smaller in overall diameter. 

The total umbilical system is enclosed in a flexible PVC jacket (rated for 130˚ F) for protection. 

Heater – Two Type "K" thermocouple wires are provided for measuring the temperature of the umbilical and the probe heater.  The typical heater consumes 18 watts/foot.

Heater nodes run the length of the umbilical every 3’.  Temperatures are normally set between 250˚ and 350˚.  The temperature is controlled by a controller usually mounted in the CEMS cabinet.


INSTALLATION: There are three things to consider with the installation of an umbilical

  • Securing the umbilical.
  • The proper length of the umbilic
  • The problems that may arise and how to prevent them.

Securing the Umbilical – Enough slack must be left at each end to connect the umbilical. 

The umbilical must be supported every 10 feet on vertical runs and every 5 feet



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