Cyclones A CENTRIFUGAL FORCE

IN AIR SAMPLING

A Presentation by

SKC Inc.

www.skcinc.com

SIZE-SELECTIVE SAMPLING TRADITIONAL CRITERIA

FOR PARTICULATE MATTER

Total

Respirable

SIZE-SELECTIVE SAMPLING NEW INTERNATIONAL CRITERIA

•Inhalable

•Thoracic

•Respirable

RELATIVE SIZE OF PARTICLES

1 4 7 10 30 100

•Respirable:Respirable:4 micron4 micron

•Thoracic:Thoracic:10 micron10 micron

•Inhalable:Inhalable:100 100 micronmicron

RESPIRABLERESPIRABLE

THORACICTHORACIC

INHALABLEINHALABLE

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. 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)

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!

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)

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.

www.skcinc.com