with a 3.4µm filter for C-H absorbance measures the hydrocarbon content in the extract. The minimum detection for this method using a portable fixed filter infrared analyser is 2ppm.
MEASUREMENT OF FOG USING INFRARED ABSORPTION AND HEXANE EXTRACTION
Hexane is a desirable solvent because disposal is simple and it is the solvent used in EPA Method 1664. Hexane must be evaporated off so that it does not interfere with the measurement of oil and grease. This poses a problem for the traditional infrared method of using a quartz cuvette and transmission as described above. To overcome this limitation, an ATR (attenuated total reflection) sample plate (Figure 2) is used as an alternate sample holder to the quartz cuvette. For this analysis, a measured amount of the hexane extract is deposited directly on the ATR crystal. The hexane evaporates and leaves a film of oil and grease on the surface of the crystal. The infrared beam is internally reflected down the ATR crystal and the output is focused directly on the detector situated at the opposite end of the infrared source. Since there is an evanescent wave that penetrates into the film of oil and grease at each internal reflection point, energy is absorbed at the C-H absorption band without the hydrocarbon interference from the hexane. The minimum detection for the hexane extraction is 8ppm.
FOG MEASUREMENT PROCEDURE
The advantages of infrared analysis over the gravimetric method are simplicity and speed. Portable, relatively inexpensive fixed-filter infrared analysers, such as the Wilks InfraCal TOG/TPH Analyser (Photo 1), are currently employed by regulators and industrial pre-treatment personnel for on-site testing. The extraction and measurement procedure involves several simple steps, which means that an operator with minimal training can perform the analysis.
minutes) the result is displayed. For the ASTM method D 7066-04, the cuvette is filled with the S-316 or perchloroethylene extract and placed in the analyser. After 30 seconds, the result is displayed. Typically, an analysis from sample collection to final result takes less than 10 minutes.
SUMMARY
The management of a process is greatly enhanced by the availability of accurate, 'live' data, so portable infrared analysers enable operators of pre-treatment systems to easily assess efficiency. In addition, regulators and water companies can immediately determine who their ‘FOG clog’ offenders are.
Plant operators are able to take samples both before and after treatment in order to study the process under differing load conditions, so that system parameters can be changed quickly without having to wait for laboratory results.
Most importantly, effluent containing fats, oil and grease above the regulatory limits can be diverted before a blockage is caused.
References On Site FOG Measurement
The sample is collected in a container. The solvent, hexane, perchloroethylene or S-316, is added at a ratio of one part solvent to 10 parts sample. After shaking for two minutes, the hexane, which is lighter than water, will rise to the top carrying dissolved oil and grease with it. The S-316 and perchloroethylene are heavier than water and require an inverted container such as a separatory funnel or a jar with a septum to remove the solvent.
Figure 2: The measurement of IR absorption of an oil sample with an ATR sample plate
For the hexane method the extract is placed on the ATR crystal and after evaporation (about three
1. Assessment of Grease Interceptor Performance(Supplemental Report to 03-CTS-16T) Joel J. Ducoste, North Carolina State University; Kevin M. Keener, Purdue University; John W. Groninger, Southern Illinois University; Leon M. Holt, Town of Cary; Copyright 2008 by the Water Environment Research Foundation
2. EPA Method 1664, RevisionA: N-Hexane Extractable Material (HEM;Oil and Grease) and Silica Gel Trated N-Hexane Extractable Material (SGT-HEM; Non-polar Materia) by extraction and Gravimetry, United States Environmental Protection Agency, Office of Water, EPA-821-R-98-002, February 1999.
Yorlab Reports 20 Percent Sales Rise
Yorlab has increased sales by more than 20 per cent over the last 12 months.
Financial Director Kirstin Davis says “Although the reported revenues were flattered by the Euro to sterling exchange rates for European and African sales, these figures represent significant volume increases in all of our major markets which include the UK , Africa and the Indian Sub continent”.
Kirstin Davis, Financial Director, Yorlab
She adds that “the takeover of Chester Scientific last year has also been a significant boost, adding a couple of major blue chip companies in the northwest of England to our customer base, this has helped push sales beyond our expectations.
We are determined to keep the growth going
without compromising our levels of service to our customers. As a small business it is essential that we have a constant eye on the satisfaction of our customers. Direct contact with customers is an essential element of our business philosophy. We work in partnership with our customers from conception to the finished article; we have recently developed a variation on the traditional essential oil still (pictured), working closely with a customer who was interested in some of the harder to separate volatile compounds. Working in partnership enables us to get it exactly right resulting in customer satisfaction.
We also seek and welcome feedback, it’s important to us to know what we are doing right and where we are going wrong.”
Ray Smith, Glassblowing Manager, with a essential oil still made in collaboration with the customer
Circle no. 590
YORLAB
Our current product and service portfolio represents 30 years of experience, expertise and
innovation, we are constantly striving to improve our products and our processes.
OUR BRAND NEW WORKSHOP IS EQUIPPED WITH MODERN CUTTING, GRINDING, POLISHING, EDGING, DRILLING AND SANDBLASTING FACILITIES.
YORLAB OFFER A MODIFICATIONS AND REPAIRS SERVICE FOR MOST STANDARD ITEMS OF LABORATORY GLASSWARE AND EQUIPMENT.
WE ALSO OFFER A BESPOKE MANUFACTURE SERVICE FOR LABORATORY TEST EQUIPMENT.
TELEPHONE: 01904 488599
FOR FURTHER DETAILS
2 Chessingham Park Common Road Dunnington York YO19 5SE
Email:
sales@yorlab.co.uk www.yorlab.co.uk
TEL.01904 488599 FAX.01904 489358
Circle no. 591
Laboratory Products Focus
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