Pilat (U. of W.) Source Test
Cascade Impactors
History:
The Pilat Mark III Source Test Cascade Impactor was developed at the University
of Washington (Seattle, Washington) Department of Civil Engineering by
Professor M. J. Pilat and graduate students specifically for measuring
the particle size distribution in stacks and ducts at air pollution emission
sources. The Pilat Mark I Cascade Impactor was developed in 1968
in order to provide particle size distribution data needed for research
projects at the University of Washington concerning the control of particulate
emissions with wet scrubbers and the relationship of plume opacity to particle
properties. Using data obtained during extensive use of the
Mark I and II models for particle size measurements at aluminum reduction
plants and Kraft recovery boilers, the improved Mark III model was designed
and constructed. The Pilat Cascade Impactors have been have been
successfully used to measure the particle size distribution and the particle
collection efficiency at many emission sources including: coal fired
power boilers, Kraft pulp mill recovery boilers, sulfite pulp mill recovery
boilers, hog fuel (wood-waste) boilers, aluminum reduction plants, and
oil fired turbines.
Tests conducted by the Southern Research Institute (of Birmingham, Alabama)
under an Environmental Protection Agency contract, as reported by McCain,
et al, (1973) showed that this Pilat Mark III Cascade Impactor appeared
to have the least particle blow-off and re-entrainment problems compared
to the other impactors. The California Air Resources Board has used
the Pilat Mark V cascade impactor for ARB's Method 501 "Determination
of Size Distribution of Particulate Matter from Stationary Sources".
For price list go to: Prices
(2002)
Features
of Cascade Impactors:
-
Separates 0.25 to 20 micron diameter solid or liquid aerosol particles
into 8 size classifications (Mark III) or 12 classifications (Mark V) for
later weighing and/or chemical analysis.
-
In stack sampling and particle size minimizes problems of losses of particle
to the tubing walls and of water vapor condensation.
-
Isokinetic sampling for a true representative particle sample.
-
Separate particle collection plates which allow for obtaining multiple
samples with a single cascade impactor unit.
-
Lightweight disposable collection plate inserts of stainless steel foil
allow improved weighing precision and reduces need for many sets of collection
plates.
-
Built-in 47mm diameter filter holder in the cascade impactor outlet.
-
Collection plates designed for minimal particle sample handling loss.
-
Sample at 0.1 to 1.0 acfm gas flow rate (2.8 to 28 liters per minute).
Product
List:
-
Mark III Source Test Cascade Impactor
-
Mark V Source Test Cascade Impactor
-
Right Angle Sampling Attachment
-
Precutter
-
Mark 8 High Grain Loading Impactor
-
Thimble Filter Holder
-
Substrates
Pollution Control Systems Corporation
PO Box 15770, Seattle, WA
98115
FAX: (206) 523-7221
Phone: (206) 523-7220
jwpaul@earthlink.net
Mark III Source Test Cascade Impactor (Item 3-1)
A photo of the Pilat Mark III Cascade Impactor disassembled parts is
presented in Figure 1. The cascade impactor operates by separating
the particles into a number of size fractions. The number 1 jet stage
is the inlet sampling nozzle (a single jet of 0.5" diameter). The
number 2 jet stage has six 0.228 inch diameter holes. Jet stages
3, 4, 5, 6, and 7 have multiple holes of decreasing diameter. The particle
collection plates are annular, or doughnut shaped. The 47mm diameter
filter holder in the outlet is shown on the right-hand side of Figure 1.
The separation of the aerosol particles is accomplished by passing the
sample gases and aerosol particles through jet orifices of successively
lesser diameter and increasing gas jet velocities as is shown in Figure
2. The aerosol particles of sufficient size are inertially collected
on the first particle collection plate downstream of the first jet stage
which is the single jet of the sampling nozzle. Additional details
are provided in the Operations Manual which can be obtained
at the link under "Publications".
Figure 1
Figure 2
Construction:
-
Cylindrical casing, jet stages, inlet section, outlet section, and collection
plates - all 316 stainless steel.
-
Internal seals - Viton or silicone O-rings (can be omitted for high temperature
applications).
-
Assembled length - 10 inches (25 centimeters) including nozzle;
2.9 inches outside diameter.
-
Weight - 9 pounds (4.1 kilograms)
-
Weight of stainless steel foil collection plate insert - about 1 gram.
Mark V Source Test Cascade Impactor (Item 5-1)
The Mark V cascade impactor uses 11 jet stages and provides 12 particle
size classifications. It is useful in testing in higher particle
mass concentrations, such as exists at the inlet of particle control devices.
The jet stages, collection plates, inlet section, and outlet section of
the Mark V are interchangeable with the Mark III model and this allows
for flexibility in arranging the jet stages. The Mark V includes
10 multi-jet stages and the number 1 inlet sampling nozzle stage which
can be arrange in at least 4 different jet stage configurations depending
on the desired aerodynamic cut diameters (d50's). It operates in
the 0.1 to 1.0 acfm gas sampling flow rate range. The gas flow rate
trajectories and jet stages for the Mark III and Mark V Pilat Source Test
Cascade Impactors are schematically shown in Figures 3 and 4.
Fig. 4 Pilat (U. of W.) Mark III Cascade Impactor Fig. 5
Pilat (U. of W.) Mark V Cascade Impactor
Precutter (Item 12-1)
The PCSC Precutter attaches to the inlet section of the Mark III and
Mark V cascade impactors. It provides a similar cut diameter to the
first stage of the impactors (approximately 17 microns at 100 degrees F
and a flowrate of 0.5 acfm), while offering increased large particle collection
capacity. The particles are collected in the cylindrical chamber
of the precutter. Use of the precutter enables sampling in a standard
3 inch diameter test port. Figure 5 shows the PCSC precutter with
an attached nozzle and three additional nozzles.
Fig. 5 PCSC Precutter 
Right Angle Sampling Attachment (Item 13-1)
The Right Angle Sampling Attachment replaces the inlet section of the
Mark III and Mark V. With a special nozzle attached, this unit can
fit into a 4 inch diameter test port. It provides a similar cut diameter
as the first stage in the standard configuration. This attachment
will accept collection plate inserts or substrates identical to the first
collection plate in the Mark III and Mark V. Figure 6 shows the Right
Angle Sampling Attachment with Nozzle. The Right Angle Sampling attachment
uses either the longer Item 4-1 sampling nozzles or the shorter Item 13-2
sampling nozzles (the Item 13-2 shorter nozzles are of 3/16", 1/4", 3/8",
5/16", and 1/2" inlet diameter). The Right Angle Sampling Attachment
with a longer nozzle is shown in Figure 6.
Fig. 6 Right Angle 
Sampling Attachment
Mark 8 High Grain Loading
Impactor (Item 8-1)
The Pollution Control Systems Corporation Mark 8, High Grain Loading (HGL)
Impactor offers the user the ability to obtain particle size distribution
information in gas streams where the high concentration of particle matter
present makes sampling with our standard models difficult, especially for
longer sampling periods.
This 316 stainless steel sampler provides size information in four size
ranges by the use of three impaction jet stages followed by the outlet
final filter. A description of the stages, along with the effective
aerodynamic cut diameters, d50's, that would be obtained if sampling at
a gas flow rate of 0.5 acfm (14.2 liters per minute) at 70 degrees F is
outlined below.
| Jet Stage 1 |
Impaction Chamber with 90o
inlet |
10.8 microns |
| Jet stage 2 |
Impaction Chamber |
5.8 microns |
| Jet stage 3 |
Impaction Chamber |
1.5 microns |
| Final Collection Stage 4 |
43 X 123 mm thimble filter |
|
The HGL Impactor offers distinct, convenient operating features.
The utilization of a 90o inlet configuration offers ease of
access at many varied sampling locations. The thimble filter
chamber used for this instrument is the EPA Method 17 accessory offered
individually by Pollution Control Systems Corporation as part of our product
line. This uses commercially available 43 X 123 mm thimble filters
of either single or double thickness, made of cellulose or glass fiber
media for different sampling requirements. This thimble filter chamber
can be used alone to obtain total particulate matter mass loading as well
as in part of the HGL configuration. The use of interchangeable
parts also allows the user to obtain a conversion kit to convert to a standard
Pilat (U. of W.) Mark III cascade impactor at a substantial savings.
Figure 7 shows the Mark 8 HGL impactor kit which includes 6 isokinetic
sampling nozzles (1/8", 3/16", 1/4", 5/16", 3/8", and 1/2" inlet diameters),
one precutter wrench, and two body wrenches.
Fig. 7 Mark 8 High 
Grain Loading Impactor
Thimble Filter Holder (Item 9-1)
The EPA Method 17 (in-stack filter sampling) thimble filter holder is
a special inlet section to the Mark III and Mark V cylindrical casing which
will hold a 43 x 123 mm diameter thimble filter. The Mark III or
Mark V cylindrical casing and outlet section are combined with the Thimble
Filter Holder inlet section (Item 9-1) to provide the complete thimble
filter holder. The thimble filter fits onto a tapered inlet tube
and a tapered retaining ring holds the filter in place. The retaining
rings are supplied to accommodate different thickness thimbles available.
Substrates (Items 7-1 through 7-6)
Substrates (the sampled particles deposit on the substrate surface)
are available in Reeve Angle (borosilicate glass; 58% SiO2, 11% B2O3) 934
AH glass-fiber filters and QM-A ultra-pure quartz (99% SiO2) microfiber
filter material. The QM-A ultra-pure quartz microfiber filter material
contains virtually no alkaline earth metals and is therefore recommended
for sampling and subsequent analysis of particle samples where acidic gases
such as SO2 and NO2 are encountered. Artifact production of sulfates
and nitrates on the filter is virtually eliminated with QM-A ultra-pure
quartz filters. The low background levels of heavy metals in the
QM-A filter substrates make it suitable for X-ray fluorescence and neutron
activation chemical analysis.) These pre-cut substrates should be
mounted in the stainless steel foil inserts for ease of handling and to
eliminate loss of sample or substrate.
Pollution Control Systems
Corporation
PO Box 15770, Seattle, WA
98115
FAX: (206) 523-7221
Phone: (206) 523-7220
jwpaul@earthlink.net
Pricing
(Revised
March 26, 2002)
Publications:
-
Operations
Manual for Pilat (U of W) Mark 3 and Mark 5 Source Test Cascade Impactors
-
Pegnam,
R. and M. Pilat, Airborne Particulate Emissions from a Chromic Acid Anodizing
Process Tank, Air & Waste J., Vol. 42 (March 1992) Adobe Acrobat
PDF File
-
Pilat,
M. and T. Steig, Size Distribution of Particulate Emissions from a Pressurized
Fluidized Bed Coal Combustion Facility, Atmospheric Environment, Vol. 17,
pp. 2429-2433 (December 1983) Adobe Acrobat PDF File
