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Gilson Company, Inc.
3.0 SAMPLE CAPACITY
Capacity of the Porta-Screen
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 degradation 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
depends on the specifications
®
Minimum
Sample Weight
kg (lb)
1 (2)
2 (4)
5 (11)
10 (22)
15 (33)
20 (44)
35 (77)
With fine series trays, (No.8 to No.200), the limiting tray should
contain no more than approximately 4g per square 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
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 designed for
this purpose, such as the Gilson Model SS-8R Sieve Shaker.
4.0 MAINTENANCE & DISASSEMBLY
NOTE: Please read and understand all safety and
maintenance instructions for the Gilson Porta-Screen
before performing maintenance on it.
WARNING!
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
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 Connecting Rod
Page 6
Gilson Porta-Screen
is designed primarily for use in the
®
with trays and pan, filling all the
®
®
: PS-3 & PS-4
®
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