Cyclones A CENTRIFUGAL FORCE IN AIR SAMPLING

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Cyclones A CENTRIFUGAL FORCE IN AIR SAMPLING

• A Presentation by
• SKC Inc.

www.skcinc.com
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SIZE-SELECTIVE SAMPLING TRADITIONAL CRITERIAFOR
PARTICULATE MATTER

• Total

• Respirable

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SIZE-SELECTIVE SAMPLING NEW INTERNATIONAL
CRITERIA

• Inhalable
• Thoracic
• Respirable

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RELATIVE SIZE OF PARTICLES

• Respirable
• 4 micron
• Thoracic
• 10 micron
• Inhalable
• 100 micron

1 4 7 10 30 100
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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

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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 thegas 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

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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
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50 CUT-POINTA 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

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50 CUT-POINT ON THE COLLECTION EFFICIENCY CURVE
50 cut point is 4 µm
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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

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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

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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

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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

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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

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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

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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

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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 calibrator
• The chamber fits both the 25-mm and the 37-mm
  aluminum cyclones
• (Cat. No. 225-01-03)

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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!
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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. 225-111)
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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.

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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

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POST-SAMPLE CLEANING

• After sampling, clean all parts of the cyclone
  with mild soapy water
• Dont 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

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CYCLONES A CENTRIFUGAL FORCE IN AIR SAMPLING
SKC INC. www.skcinc.com