CEMS From A-Z: A Multi-Part Series - Extractive CEMS Umbilical (Part 3)
This issue continues our presentation of a comprehensive look at 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.
- One 3/8" PFA Teflon tube for transportation calibration gas to the probe.
- One 3/8" Teflon tube for transportation sample CEMS.
- 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