Silica
gel is a spherical bead consisting of 97% silica and 3%
alumina. It is available in two types: indicating, a translucent
bead impregnated with blue color and non-indicating, which
is a brown translucent color.
Since silica gel fractures in the presence of liquid water.
It must be protected by a 10% to 15% (by weight) layer of
activated alumina as a water buffer on the inlet side of
the desiccant bed. Dew points to -40°F and lower may
be achieved with silica gel depending on dryer design and
operating conditions.
Physical
Properties |
|
Non-Indicating |
Indicating |
|
| Color
and form |
Translucent
brown bead |
Translucent
blue bead |
| Size |
3.5
mm (.14") |
3.5
mm (.14") |
| Bulk
Density |
49
lbs/cu.ft. |
49
lbs/cu.ft. |
| Surface
area |
3.67
x 10 6 sq ft/lb |
3.67
x 10 6 sq ft/lb |
| |
|
|
| Static
adsorption |
|
|
| Humidity |
|
|
| 100%
RH |
39.0% |
37.0% |
| 90%
RH |
36.3% |
34.0% |
| 60%
RH |
33.3% |
29.0% |
| 10%
RH |
6.4% |
4.9% |
|
|
|
|
Non-Indicating
Silica Gel |
Indicating
Silica Gel |
Silica
Gel Package Sizes |
| Non-Indicating |
Indicating |
|
| 33-0315 |
5
lb pail |
33-0316 |
5
lb pail |
| 33-0243 |
25
lb pail |
33-0246 |
25
lb pail |
| 33-0244 |
50
lb bag |
33-0247 |
50
lb bag |
| 33-0245 |
330
lb steel drum |
33-0248 |
330
lb steel drum |
1.
High moisture retention capacity under dynamic conditions
Used in some heated type regenerative dryers. Under dynamic
conditions, a higher design capacity rating and lower regeneration
temperature can be used.
2. Uniform bead shape
This shape provides lower pressure drop and less abrasion
than granular types. Smooth beads also pack uniformly to
minimize channeling.
3. Provides visual check of
desiccant condition (indicating type only)
Beads are impregnated with a moisture indicator. The color
changes from blue to pink as moisture is adsorbed. Reduced
capacity of this type is due to the presence of indicator
material in its pores.
