TSI Instruments SidePak AM520, User Manual

Page: 62 / 98

Chapter 4 46
Using and Maintaining the Respirable Cyclone
The 10-mm Nylon
Dorr-Oliver Cyclone
included with the
AM520/AM520i can
be used to
differentiate between
the respirable fraction and other portions of the ambient aerosol. It is
ideal for making breathing zone measurements because it can be
attached to a worker's clothing near his or her head. TSI
®
supplies a
U-tube and clip with the cyclone specifically for this purpose.
4 µm is internationally accepted as the 50% cut-off size for respirable
aerosols. Particles larger than 4 µm impact onto the surfaces of the
upper respiratory tract and cannot reach the lungs. The cyclone
accessory provided with SidePak
™ AM520/AM520i is designed to
provide a cut-off at 4 µm. This is specified as a D
50
(50%) sharp
cut-off at 4 µm.
The cyclone works by forcing the particle-laden air sample to swirl
inside the cyclone body. Larger (higher mass) particles cannot follow
the air stream and become trapped while smaller particles stay in the
air stream and pass through. When using the cyclone, assume that all
particles smaller than the cut-off size pass through and all larger
particles become trapped in the grit potentiometer.
The cut-off size for any cyclone is dependent on flow rate.
N O T I C E
It is very important that the sample flow rate through the SidePak
™
AM520/AM520i monitor be set at 1.7 liters per minute (L/min). If
some other flow rate is set, the cut-off size will be unknown.
1. Install the standard inlet (unmarked) on the SidePak
™
AM520/AM520i body without an impactor disk inside.
2. Attach the cyclone and sample tube onto the inlet.
3. Adjust the flow rate to 1.7 L/min. See the Operation chapter for
instructions on setting the flow rate.
The SidePak
™ monitor and cyclone are now ready to use. Attach the
cyclone to the individual test subject's clothing using the U-tube and
clip provided with the cyclone.