Hydrocarbon Processing Issue 03 | Page 6

SAFETY PARAMAGNETIC OXYGEN ANALYSIS FOR SAFETY- CRITICAL MEASUREMENTS It can be used to sterilize medical supplies and devices, but is more commonly used as an intermediate in the production of other chemicals, including ethylene glycol (polyester fibers, fiberglass, blending anti-freezing agents) and polyethylene terephthalate (PET) resin, used for packaging film and bottles. To provide safety-critical O 2 monitoring in the SIS, Servomex supplies the SERVOTOUGH OxyExact 2200. SIL 2 VOTING SYSTEMS In a three-analyzer voting system, the process depends on the measurement made by the majority of analyzers. So, if only one analyzer detects a significant change, it is “outvoted” by the other two and no action is taken. However, if two analyzers detect a change, their reading is held as correct and action is taken. This may range from alerting the operator to automatically halting the process. Voting systems allow problems with analyzers to be detected early without endangering the process. If two analyzers agree on a measurement and the third varies, it indicates a potential problem that can be investigated and corrected before the process is affected. PARAMAGNETIC TECHNOLOGY Both the SERVOTOUGH OxyExact 2200 and SERVOTOUGH Oxy 1900 are built around Servomex’s high-precision Paramagnetic sensing technology, which provides reliable, accurate and stable percentage measurements of oxygen. Ethylene oxide, which can be used as an intermediate in fiberglass production, is a hazardous substance. Three of these Paramagnetic oxygen analyzers are positioned in a voting system on the inlet and each outlet of the reactors. The OxyExact 2200 can also be used to ensure the purity of oxygen feedstock (in the 90-100% O 2 range) at the beginning of the production process. A high-specification process O 2 analyzer, the OxyExact 2200 uses an intelligent three-enclosure system that facilitates the simplified and versatile sampling of any flammable gas up to 100% O 2 . It does not require pre-sample drying in many cases, so dramatically reduces ongoing costs. Find out more at: servo