CYCLONES Traditional workplace samplers for respirable particulate matter Named for the rotation of air within the chamber Function on the same principle as a centrifuge Use rapid circulation of air to separate particles according to their aerodynamic diameter
WHY USE A CYCLONE? Some sampling methods require collection of the respirable fraction of particulates. Respirable particulates are: Smaller than 10 microns in diameter Penetrate deep into the gas exchange region of the lung Cyclones enable collection of the respirable fraction only Collecting larger, non- respirable particulates would inflate results of sample, overestimating exposure
WHY USE A CYCLONE ? Cyclones separate larger, non-respirable particles from smaller, respirable particles Small particles are whirled up into the filter Large particles fall into the red “grit pot”
50% CUT-POINT: A PERFORMANCE SPECIFICATION The 50% cut-point is often used to describe the performance of size selective samplers It is the particle size that the device can collect with 50% efficiency Particles smaller than the 50% cut-point are collected with an efficiency greater than 50%. Larger particles are collected with an efficiency less than 50%
50% CUT-POINT ON THE COLLECTION EFFICIENCY CURVE 50% cut point is 4 µm
THE NEW INTERNATIONAL CRITERIA Specifies a 50% cut- point of 4 μm for respirable dust samplers, including cyclones This criteria has been adopted by ACGIH, ISO, CEN, and many agencies worldwide
CYCLONE PERFORMANCE There are a variety of cyclones on the market Each cyclone has different operating specifications and performance criteria All cyclones are not created equal! Be sure you know the flow rate specified to achieve the desired cut- point before using a cyclone
CYCLONES AVAILABLE FROM SKC Aluminum Cyclone Meets ACGIH/ISO/CEN respirable curve at 2.5 L/min Eliminates adverse electrostatic effects Specified in NIOSH Method 7500 for silica and 0600 for respirable particulates
CYCLONES AVAILABLE FROM SKC GS-3 Cyclone Conductive plastic Safe for underground mine use Eliminates adverse electrostatic effects Meets ACGIH/ISO/CEN respirable curve at 2.75 L/min
CYCLONES AVAILABLE FROM SKC GS-1 Cyclone Constructed of same conductive plastic material as GS-3 Single inlet version to match specifications of Dorr-Oliver Meets ACGIH/ISO/CEN respirable curve at 2.0 L/min
CYCLONES AVAILABLE FROM SKC LTD. UK Plastic Cyclone Meets ACGIH/ISO/CEN respirable curve at 2.2 L/min Leak-tested plastic construction Features a “snap together “ cassette Static dissipating
TIPS FOR SAMPLING WITH SKC ALUMINUM OR GS CYCLONES Prepare 3-piece filter cassette Place cyclone into middle ring Calibrate the pump with sampler in line Take sample at specified flow rate Remove filter and cyclone from sample train Recap and send filter to lab Clean cyclone before reuse
TIPS FOR CALIBRATION SKC Aluminum Cyclone (Cat. No /2) Has a aluminum calibration chamber that fits over the cyclone and allows standard tubing to be attached for connection to the pump calibrator The chamber fits both the 25-mm and the 37-mm aluminum cyclones (Cat. No )
TIPS FOR CALIBRATION SKC Calibration Jar (Cat. No /112) Very large jars are not recommended when calibrating with the piston- style primary calibrators like the BIOS Defender. The dead volume in the jar can affect the rise/fall of the piston causing the readings to be erroneously low!
TIPS FOR CALIBRATION SKC Calibration Jar (Cat. No /112) Use the smallest jar possible to contain the cyclone/filter assembly. SKC offers a calibration jar suitable for the SKC GS Cyclone (Cat. No )
TIPS FOR CALIBRATION Another option is the “jarless” calibration method using piston-style primary calibrators Attach the pump only to the suction port and the cyclone/filter assembly to the other port on the calibrator. This will create the same pressure drop as the sampling train assembled in the field.
SAMPLING WITH A CYCLONE Ensure the grit pot is attached during sampling otherwise, there is no size selection Use the sampling rate specified by the manufacturer to achieve the desired cut-point: SKC Aluminum: 2.5 L/min SKC GS: 2.75 L/min SKC UK: 2.2 L/min Dorr-Oliver: 1.7 L/min
POST-SAMPLE CLEANING After sampling, clean all parts of the cyclone with mild soapy water Don’t forget to clean the grit pot! Dry the cyclone Air or blow-dry Wipe with a dust-free tissue or wipe with an isopropyl alcohol moistened pad. Caution: Do not use strong solvents to clean plastic cyclones
CYCLONES A CENTRIFUGAL FORCE IN AIR SAMPLING SKC INC.