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Gilson Company, Inc.
3.0 sAMPle CAPACITy
Capacity of the Porta-Screen
tions of the test and the type and size of the material being
tested. For any given sample, the Porta-Screen's maximum
capacity is determined by the tray which has the largest
load at the end of the test. This is the limiting tray.
3.1 Coarse Aggregates
Minimum quantity of sample is usually established by the
specifications of the test procedure. For example, ASTM
C 136 "Specification for the Sieve or Screen Analysis
of Fine and Coarse Aggregates" calls for the minimum
weight of the test sample of coarse aggregates (density
such as limestone or gravel) as follows:
Normal Maximum
size of Particle
mm (in)
9.5 (3/8)
12.5 (1/2)
19.0 (3/4)
25.0 (1)
37.5 (1-1/2)
50 (2)
63 (2-1/2)
These guidelines on minimum sample size quantities are
for representative samples. Always take a much larger
amount, perhaps from several spots in a storage bin or
stockpile. Then combine and reduce them to the correct
quantity by splitting.
With coarse series trays, (2in to No.4), the limiting tray
should have no more than one layer of particles over the
wire cloth at the end of the test. Therefore, lightweight
aggregates or coal must be tested in lower sample
weights. High-density ores or pellets may be tested in
larger amounts by weight. Many light materials are also
soft, and test times should be limited to avoid degrada-
tion of the sample.
Most samples of up to 2in topsize can be handled in a
single batch without difficulty. We do not recommend the
use of trays with mesh sizes above 1-1/2in, since larger
particles become wedged in the mesh and make it difficult
to remove the trays.
3.2 Fine Aggregates
With fine series trays, (No.8 to No.200), the limiting tray
should contain no more than approximately 4g per square
depends on the specifica-
®
Minimum
sample weight
kg (lb)
1 (2)
2 (4)
5 (11)
10 (22)
15 (33)
20 (44)
35 (77)
inch of sieve surface at the end of a test. Assuming that
the material is about the density of sand, there will be
approximately 800g maximum on the limiting tray.
Since the Porta-Screen
the 2in to No.20 range, separations in finer sizes will not
be as precise. If you are testing materials exclusively in
the fine range, we recommend equipment specifically de-
signed for this purpose, such as the Gilson Model SS-8R
Sieve Shaker.
4.0 MAINTeNANCe & DIsAsseMBly
NOTe: Read and understand all safety and mainte-
nance instructions before performing maintenance
on your Porta-Screen
AlwAys disconnect and lock out electric power
before performing maintenance!
4.1 Clamping system
1. DISCONNECT AND LOCK OUT ELECTRIC POWER.
2. Load the Porta-Screen
the slots.
3. Rotate the clamp levers (#38) so that they point
down.
4. Locate the clamp adjusting nuts (#9), which are on
the lower ends of the four clamp tension rods (#7).
5. Tighten the nuts only enough to prevent the trays
from rattling when the machine is operating.
4.2 lubrication
1. DISCONNECT AND LOCK OUT ELECTRIC POWER.
2. Remove and set aside trays and pan.
3. Remove upper case cover.
4. Connection Rod Bearing: Lubricate the connect-
ing rod bearing (#52) after every 80—100 hours of
operation.
a. Rotate drive shaft (#20) slightly by hand until the
grease fitting at the lower end of the connecting
Page 6
Gilson Porta-Screen
: PS-3 & PS-4
®
is designed primarily for use in
®
.
®
with trays and pan, filling all
®
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