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Cyclone Angle |
| After a first glance at a cyclone for Industrial Hygiene or Environmental applications, logic would seem to indicate that the device must be “Vertical”! The tangential inlet should be on the side, the outlet on top and the grit pot on the bottom. Upon further consideration we realize that the centripetal force acting on the particles is many times greater than the force of gravity. However, because workers wear sampling cyclones in the vertical position but often times contort themselves into positions far from the vertical, concern arises.
About once a generation, investigators get nervous about this situation and demand proof. It is all well and good for scientists, long associated with cyclone research to say “trust me it makes no difference”, but there is always someone further up the line who demands documentary evidence. BGI is the leading manufacturer of round entry sampling cyclones and has the preponderance of peer reviewed published papers: L.C. Kenny and R.A. Gussman, "Characterization and Modelling of a Family of Cyclone Aerosol Preseparators", J. Aerosol Sci. Vol. 28, No. 4, pp. 677-688, 1997. L.C. Kenny, R.A. Gussman and M. Meyer, "Development of a Sharp-Cut Cyclone for Ambient Aerosol Monitoring Applications", J. of Aerosol Sci. and Tech., Vol. 32, No. 4, pp. 338-358, 2000. L.C. Kenny and R.A. Gussman, "A Direct Approach to the Design of Cyclones for Aerosol-Monitoring Applications", J. Aerosol Sci., Vol. 31, No. 12, pp. 1407-1420, 2000. T.M. Peters, R.A. Gussman. L.C. Kenny and R.W. Vanderpool, "Evaluation of PM2.5 Size Selectors Used in Speciation Samplers",J. Aerosol Sci and Tech., Vol. 34, No. 5, pp. 422-429, 2001. R.A. Gussman, L.C. Kenny, M. Labickas and P. Norton "Design, Calibration and Field Test of a Cyclone for PM1 Ambient Air Sampling", J. Aerosol Sci and Tech., Vol. 36, No. 3, pp. 361-365, 2002. L.C. Kenny, T. Merrifield, D. Mark, R.A. Gussman and A. Thorpe. "The Development and Designation Testing of a New USEPA-Approved Fine Particle Inlet: A Study of the USEPA Designation Process", J. Aerosol Sci and Tech., Vol. 38(S2), pp. 15-22, 2004. Every single cyclone used for area monitoring runs on its side. Inlet pointing at the sky, outlet on the side as well as the grit pot. The only possible caveat is to not have the cyclone in a completely upside down attitude when switching off the air flow. It is just possible that some material may fall out of the grit pot into the main chamber and thence onto the sampling filter, In essence getting past two “fish traps”. Copyright © 2009 by BGI / Modified:
Tuesday, February 24, 2009
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