SKC 225-380 Parallel Particle Impactor - Manual (Page 2)

2
Principle of Operation
SKC Re-usable PPI Samplers are impaction-based
fi lter samplers that perform precise size-selection
for either thoracic or respirable dust, depending
on the model. PPI Samplers contain four small
impactors in the inlet section of the device. Each
impactor features a unique 50% cut-point to target
a specifi c one-quarter segment of the ISO/CEN
curve resulting in a precise fi t along the entire
curve. A sample pump operating at 2 or 8 L/min
(2 L/min only for thoracic) pulls air through the
inlet nozzle of each impactor in the inlet plate.
Particles larger than each impactor’s 50% cut-
point are scrubbed and retained by impaction
onto the porous oiled impaction substrate
contained in each impactor. Smaller particles
continue to the standard 37-mm collection fi lter
for analysis. See www.skcinc.com/prod/225-380.
asp for performance graphs.
Media Preparation
Filters: Condition and weigh fi lters according to method used. Record the weight
as the pre-sample weight.
Impaction Substrate: Using an oiled impaction substrate reduces particle
bounce. Replacement pre-oiled disposable porous plastic discs are available as SKC Cat.
No. 225-388 (pk/200).
Inserting a Collection Filter into the PPI
The PPI will arrive already assembled. Disassemble it to
insert collection fi lter.
1. Unscrew and remove two screws that hold the inlet
plate to the base plate.
2. Lift off inlet plate to expose impaction plate.
3. Lift off impaction plate to expose base plate.
Inlet plate
Impaction
substrates (4)
Standard 37-mm
collection fi lter
and support pad
Base plate with
exhaust to pump
Dust enters here