Presentation on theme: "Cyclones A CENTRIFUGAL FORCE IN AIR SAMPLING"— Presentation transcript:
1 Cyclones A CENTRIFUGAL FORCE IN AIR SAMPLING A Presentation bySKC Inc.
2 SIZE-SELECTIVE SAMPLING TRADITIONAL CRITERIA FOR PARTICULATE MATTER TotalRespirable
3 SIZE-SELECTIVE SAMPLING NEW INTERNATIONAL CRITERIA InhalableThoracicRespirable
4 RELATIVE SIZE OF PARTICLES Respirable:4 micronThoracic:10 micronInhalable:100 micronRESPIRABLETHORACICINHALABLE
5 CYCLONESTraditional workplace samplers for respirable particulate matterNamed for the rotation of air within the chamberFunction on the same principle as a centrifugeUse rapid circulation of air to separate particles according to their aerodynamic diameter
6 WHY USE A CYCLONE?Some sampling methods require collection of the respirable fraction of particulates. Respirable particulates are:Smaller than 10 microns in diameterPenetrate deep into the gas exchange region of the lungCyclones enable collection of the respirable fraction onlyCollecting larger, non-respirable particulates would inflate results of sample, overestimating exposure
7 WHY USE A CYCLONE ? Small particles are whirled up into the filter Cyclones separate larger, non-respirable particles from smaller, respirable particlesSmall particles are whirled up into the filterLarge particles fall into the red “grit pot”
8 50% CUT-POINT: A PERFORMANCE SPECIFICATION The 50% cut-point is often used to describe the performance of size selective samplersIt is the particle size that the device can collect with 50% efficiencyParticles smaller than the 50% cut-point are collected with an efficiency greater than 50%.Larger particles are collected with an efficiency less than 50%
9 50% CUT-POINT ON THE COLLECTION EFFICIENCY CURVE 50% cut point is 4 µm
10 THE NEW INTERNATIONAL CRITERIA Specifies a 50% cut-point of 4 μm for respirable dust samplers, including cyclonesThis criteria has been adopted by ACGIH, ISO, CEN, and many agencies worldwide
11 CYCLONE PERFORMANCE There are a variety of cyclones on the market Each cyclone has different operating specifications and performance criteriaAll cyclones are not created equal!Be sure you know the flow rate specified to achieve the desired cut-point before using a cyclone
12 CYCLONES AVAILABLE FROM SKC Aluminum CycloneMeets ACGIH/ISO/CEN respirable curve at2.5 L/minEliminates adverse electrostatic effectsSpecified in NIOSH Method 7500 for silica and 0600 for respirable particulates
13 CYCLONES AVAILABLE FROM SKC GS-3 CycloneConductive plasticSafe for underground mine useEliminates adverse electrostatic effectsMeets ACGIH/ISO/CEN respirable curve at2.75 L/min
14 CYCLONES AVAILABLE FROM SKC GS-1 CycloneConstructed of same conductive plastic material as GS-3Single inlet version to match specifications of Dorr-OliverMeets ACGIH/ISO/CEN respirable curve at2.0 L/min
15 CYCLONES AVAILABLE FROM SKC LTD. UK Plastic CycloneMeets ACGIH/ISO/CEN respirable curve at2.2 L/minLeak-tested plastic constructionFeatures a “snap together “ cassetteStatic dissipating
16 TIPS FOR SAMPLING WITH SKC ALUMINUM OR GS CYCLONES Prepare 3-piece filter cassettePlace cyclone into middle ringCalibrate the pump with sampler in lineTake sample at specified flow rateRemove filter and cyclone from sample trainRecap and send filter to labClean cyclone before reuse
17 TIPS FOR CALIBRATION SKC Aluminum Cyclone (Cat. No. 225-01-01/2) Has a aluminum calibration chamber that fits over the cyclone and allows standard tubing to be attached for connection to the pump calibratorThe chamber fits both the 25-mm and the 37-mm aluminum cyclones(Cat. No )
18 TIPS FOR CALIBRATION SKC Calibration Jar (Cat. No. 225-111/112) 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!
19 TIPS FOR CALIBRATION SKC Calibration Jar (Cat. No. 225-111/112) Use the smallest jar possible to contain the cyclone/filter assembly. SKC offers a calibration jar suitable for the SKC GS Cyclone (Cat. No )
20 TIPS FOR CALIBRATIONAnother option is the “jarless” calibration method using piston-style primary calibratorsAttach 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.
21 SAMPLING WITH A CYCLONE Ensure the grit pot is attached during sampling otherwise, there is no size selectionUse the sampling rate specified by the manufacturer to achieve the desired cut-point:SKC Aluminum: 2.5 L/minSKC GS: 2.75 L/minSKC UK: 2.2 L/minDorr-Oliver: 1.7 L/min
22 POST-SAMPLE CLEANINGAfter sampling, clean all parts of the cyclone with mild soapy waterDon’t forget to clean the grit pot!Dry the cycloneAir or blow-dryWipe with a dust-free tissue or wipe with an isopropyl alcohol moistened pad.Caution: Do not use strong solvents to clean plastic cyclones
23 A CENTRIFUGAL FORCE IN AIR SAMPLING CYCLONESA CENTRIFUGAL FORCE IN AIR SAMPLINGSKC INC.